Title:	Easy and Powerful Web Servers
Version:	0.1.0
Description:	Automatically create a web server from annotated 'R' files or by building it up programmatically. Provides automatic 'OpenAPI' documentation, input handling, asynchronous evaluation, and plugin support.
License:	MIT + file LICENSE
Encoding:	UTF-8
RoxygenNote:	7.3.2
Depends:	R (≥ 4.1)
Imports:	base64enc, cli, fiery (≥ 1.3.0), firesafety, firesale, firestorm, fs, jsonlite, promises, R6, ragg, rapidoc, readr, reqres (≥ 1.0.0), rlang (≥ 1.1.0), routr (≥ 1.0.0), roxygen2, stringi, svglite, utils, webutils, yaml
Suggests:	arrow, callr, geojsonsf, htmlwidgets, later, mirai, nanoparquet, quarto, redoc, shiny, storr, swagger, testthat (≥ 3.0.0)
VignetteBuilder:	quarto
URL:	http://plumber2.posit.co/, https://github.com/posit-dev/plumber2
BugReports:	https://github.com/posit-dev/plumber2/issues
Config/testthat/edition:	3
NeedsCompilation:	no
Packaged:	2025-09-17 14:36:52 UTC; thomas
Author:	Thomas Lin Pedersen [aut, cre], Posit Software, PBC [cph, fnd]
Maintainer:	Thomas Lin Pedersen <thomas.pedersen@posit.co>
Repository:	CRAN
Date/Publication:	2025-09-22 18:30:02 UTC

plumber2: Easy and Powerful Web Servers

Description

Automatically create a web server from annotated 'R' files or by building it up programmatically. Provides automatic 'OpenAPI' documentation, input handling, asynchronous evaluation, and plugin support.

Author(s)

Maintainer: Thomas Lin Pedersen thomas.pedersen@posit.co (ORCID)

Other contributors:

• Posit Software, PBC (03wc8by49) [copyright holder, funder]

See Also

Useful links:

• http://plumber2.posit.co/

• https://github.com/posit-dev/plumber2

• Report bugs at https://github.com/posit-dev/plumber2/issues

Router control flow

Description

In plumber2 your API can have multiple middleware that a request passes through. At any point can you short-circuit the remaining middleware by returning Break, which instructs plumber2 to return the response as is. Returning Next indicates the opposite, ie that the request should be allowed to pass on to the next middleware in the chain. A handler function that doesn't return either of these are assumed to return a value that should be set to the response body and implicitely continue to the next middleware.

Usage

Next

Break

should_break(x)

Arguments

Value

A boolean value

Examples

# should_break() only returns TRUE with Break

should_break(10)

should_break(FALSE)

should_break(Next)

should_break(Break)

The Plumber2 Class

Description

This class encapsulates all of the logic of a plumber2 api, and is what gets passed around in the functional api of plumber2. The Plumber2 class is a subclass of the fiery::Fire class. Please consult the documentation for this for additional information on what this type of server is capable of. Note that the Plumber2 objects are reference objects, meaning that any change to it will change all instances of the object.

Initialization

A new Plumber2-object is initialized using the new() method on the generator:

However, most users will use the functional api of the package and thus construct one using api()

Copying

As Plumber2 objects are using reference semantics new copies of an api cannot be made simply be assigning it to a new variable. If a true copy of a Plumber2 object is desired, use the clone() method.

Super class

fiery::Fire -> Plumber2

Active bindings

Methods

Public methods

• Plumber2$new()

• Plumber2$format()

• Plumber2$ignite()

• Plumber2$add_route()

• Plumber2$request_handler()

• Plumber2$message_handler()

• Plumber2$redirect()

• Plumber2$parse_file()

• Plumber2$add_api_doc()

• Plumber2$add_shiny()

• Plumber2$forward()

• Plumber2$clone()

Method new()

Create a new Plumber2 api

Usage

Plumber2$new(
  host = get_opts("host", "127.0.0.1"),
  port = get_opts("port", 8080),
  doc_type = get_opts("docType", "rapidoc"),
  doc_path = get_opts("docPath", "__docs__"),
  reject_missing_methods = get_opts("rejectMissingMethods", FALSE),
  ignore_trailing_slash = get_opts("ignoreTrailingSlash", TRUE),
  max_request_size = get_opts("maxRequestSize"),
  shared_secret = get_opts("sharedSecret"),
  compression_limit = get_opts("compressionLimit", 1000),
  default_async = get_opts("async", "mirai"),
  env = caller_env()
)

Arguments

Returns

A Plumber2 object

Method format()

Human readable description of the api object

Usage

Plumber2$format(...)

Arguments

Returns

A character vector

Method ignite()

Begin running the server. Will trigger the start event

Usage

Plumber2$ignite(
  block = FALSE,
  showcase = is_interactive(),
  ...,
  silent = FALSE
)

Arguments

Method add_route()

Add a new route to either the request or header router

Usage

Plumber2$add_route(name, route = NULL, header = FALSE, after = NULL, root = "")

Arguments

Method request_handler()

Add a handler to a request. See api_request_handlers for detailed information

Usage

Plumber2$request_handler(
  method,
  path,
  handler,
  serializers,
  parsers = NULL,
  use_strict_serializer = FALSE,
  download = FALSE,
  async = FALSE,
  then = NULL,
  doc = NULL,
  route = NULL,
  header = FALSE
)

Arguments

Method message_handler()

Add a handler to a WebSocket message. See api_message for detailed information

Usage

Plumber2$message_handler(handler, async = FALSE, then = NULL)

Arguments

Method redirect()

Add a redirect to the header router. Depending on the value of permanent it will respond with a 307 Temporary Redirect or 308 Permanent Redirect. from and to can contain path parameters and wildcards which will be matched between the two to construct the correct redirect path.

Usage

Plumber2$redirect(method, from, to, permanent = TRUE)

Arguments

Method parse_file()

Parses a plumber file and updates the app according to it

Usage

Plumber2$parse_file(file, env = NULL)

Arguments

Method add_api_doc()

Add a (partial) OpenAPI spec to the api docs

Usage

Plumber2$add_api_doc(doc, overwrite = FALSE, subset = NULL)

Arguments

Method add_shiny()

Add a shiny app to an api. See api_shiny() for detailed information

Usage

Plumber2$add_shiny(path, app, except = NULL)

Arguments

Method forward()

Add a reverse proxy from a path to a given URL. See api_forward() for more details

Usage

Plumber2$forward(path, url, except = NULL)

Arguments

Method clone()

The objects of this class are cloneable with this method.

Usage

Plumber2$clone(deep = FALSE)

Arguments

Add a tag extension to plumber2

Description

Package authors can extend plumber2 with their own functionalities. If they wish to add a new tag to be used when writing annotated plumber2 routes they can use this function. If so, it should be called when the package is loaded.

Usage

add_plumber2_tag(tag, handler)

Arguments

Details

The handler argument must be a function with the arguments block, call, tags, values, and env. block is a list with the currently parsed information from the block. You can add or modify the values within to suit your need as well as subclass it. You should not remove any values as others might need them. call is the parsed value of whatever expression was beneath the plumber2 block. tags is a character vector of all the tags in the block, and values is a list of all the values associated with the tags (that is, whatever comes after the tag in the block). The values are unparsed. You should assume that all tags not relevant for your extension has already been handled and incorporated into block. The function must return a modified version of block. If you add a subclass to block you should make sure that a method for apply_plumber2_block() for the subclass exists.

Value

This function is called for its side effects

See Also

apply_plumber2_block()

Examples

# Add a tag that says hello when used
add_plumber2_tag("hello", function(block, call, tags, values, env) {
  message("Hello")
  class(block) <- c("hello_block", class(block))
  block
})

Create a new plumber API, optionally based on one or more plumber files

Description

This is the main way to create a new Plumber2 object that encapsulates your full api. It is also possible to add files to the API after creation using api_parse()

Usage

api(
  ...,
  host = get_opts("host", "127.0.0.1"),
  port = get_opts("port", 8080),
  doc_type = get_opts("docType", "rapidoc"),
  doc_path = get_opts("docPath", "__docs__"),
  reject_missing_methods = get_opts("rejectMissingMethods", FALSE),
  ignore_trailing_slash = get_opts("ignoreTrailingSlash", TRUE),
  max_request_size = get_opts("maxRequestSize"),
  shared_secret = get_opts("sharedSecret"),
  compression_limit = get_opts("compressionLimit", 1000),
  default_async = get_opts("async", "mirai"),
  env = caller_env()
)

is_plumber_api(x)

api_parse(api, ...)

Arguments

Value

A Plumber2 object

See Also

api_package() for creating an api based on files distributed with a package

get_opts() for how to set default options

Examples

# When creating an API programmatically you'll usually initialise the object
# without pointing to any route files or a _server.yml file
pa <- api()

# You can pass it a directory and it will load up all recognised files it
# contains
example_dir <- system.file("plumber2", "quickstart", package = "plumber2")
pa <- api(example_dir)

# Or you can pass files directly
pa <- api(list.files(example_dir, full.names = TRUE)[1])

Add a new route to either the request or header router

Description

This function allows explicit creation of routes or addition/merging of a predefined routr::Route into the router of the api. A new route can also be created with the route argument when adding a handler. However, that way will always add new routes to the end of the stack, whereas using api_add_route() allows you full control of the placement.

Usage

api_add_route(api, name, route = NULL, header = FALSE, after = NULL, root = "")

Arguments

Value

This functions return the api object allowing for easy chaining with the pipe

Using annotation

There is no direct equivalent to this when using annotated route files. However you can name your route in a file by adding ⁠@routeName <name>⁠ to the first block of the file like so.

#* @routeName my_route
NULL

All relevant blocks in the file will then be added to this route, even if the route already exist. In that way you can split the definition of a single route out among multiple files if needed.

Examples

# Add a new route and use it for a handler
api() |>
  api_add_route("logger_route") |>
  api_any(
    "/*",
    function() {
      cat("I just handled a request!")
    },
    route = "logger_route"
  )

Serve resources from your file system

Description

plumber2 provides two ways to serve files from your server. One (api_assets) goes through R and gives you all the power you expect to further modify and work with the response. The other (api_statics) never hits the R process and as a result is blazing fast. However this comes with the price of very limited freedom to modify the response or even do basic authentication. Each has their place.

Usage

api_assets(
  api,
  at,
  path,
  default_file = "index.html",
  default_ext = "html",
  finalize = NULL,
  continue = FALSE,
  route = NULL
)

api_statics(
  api,
  at,
  path,
  use_index = TRUE,
  fallthrough = FALSE,
  html_charset = "utf-8",
  headers = list(),
  validation = NULL,
  except = NULL
)

Arguments

Value

These functions return the api object allowing for easy chaining with the pipe

Using annotation

When using annotated route files the functionality of api_assets() can be achieved like this:

#* @assets my_wd/ ./
NULL

When using annotated route files the functionality of api_statics() can be achieved like this:

#* @statics my_docs/ ~/
#* @except my_secret_folder/
NULL

Examples

# Add asset serving through routr route
api() |>
  api_assets("my_wd/", "./")

# Add asset serving directly
api() |>
  api_statics("my_docs", "~/", except = "my_secret_folder/")

Persistent server-side data storage

Description

While using a session cookie is a convenient solution to persistent data storage between requests it has the downside of requiring the data to be passed back and forth between server and client at every exchange. This makes it impractical for all but the smallest snippets of data. An alternative strategy is to use server-side storage which this function facilitates. It uses the firesale plugin under the hood to provide a list-like interface to a storr-backed key-value store. storr in turn provides interfaces to a range of backends such as redis, LMDB, and databases supported by DBI. Further it provides simpler (but setup-free) solutions such as using an environment (obviously less persistent) or a folder of rds files.

Usage

api_datastore(
  api,
  driver,
  store_name = "datastore",
  gc_interval = 3600,
  max_age = gc_interval
)

Arguments

Details

Once you turn the datastore on with this function your request handlers will gain access to a new argument (defaults to datastore but this can be changed with the store_name argument). The datastore argument will contain a list holding two elements: global and session which in turn will be list-like interfaces to the underlying key-value store. The global element access a store shared by all sessions whereas the session element is scoped to the current session. Depending on the value of max_age the session specific data is purged once a certain amount of time has passed since the last request from that session.

Value

These functions return the api object allowing for easy chaining with the pipe

Using annotation

Session cookie setup doesn't have a dedicated annotation tag, but you can set it up in a ⁠@plumber⁠ block

#* @plumber
function(api) {
  api |>
    api_datastore(storr::driver_dbi(...))
}

Examples

api() |>
  api_datastore(storr::driver_environment()) |>
  api_get("hello", function(datastore) {
    if (length(datastore$session) == 0) {
      datastore$global$count <- (datastore$global$count %||% 0) + 1
      datastore$session$not_first_visit <- TRUE
      paste0("Welcome. You are visitor #", datastore$global$count)
    } else {
      "Welcome back"
    }
  })

Configure your API for serving documentation for itself

Description

The OpenAPI standard offers a way to describe the various endpoints of your api in machine- and human-readable way. On top of this, various solutions have been build to generate online documentation of the API based on a provided OpenAPI spec. plumber2 offers support for RapiDoc, Redoc, and Swagger as a UI frontend for the documentation and will also generate the spec for you based on the tags in parsed files. If you are creating your API programmatically or you wish to add to the autogenerated docs you can add docs manually, either when adding a handler (using the doc argument), or with the api_doc_add() function

Usage

api_doc_setting(api, doc_type, doc_path)

api_doc_add(api, doc, overwrite = FALSE, subset = NULL)

Arguments

Value

These functions return the api object allowing for easy chaining with the pipe

Using annotation

When using annotated route files documentation is automatically generated based on the annotation. The following tags will contribute to documentation:

• ⁠@title⁠

• ⁠@description⁠

• ⁠@details⁠

• ⁠@tos⁠

• ⁠@license⁠

• ⁠@contact⁠

• ⁠@tag⁠

• ⁠@param⁠

• ⁠@query⁠

• ⁠@body⁠

• ⁠@response⁠

• ⁠@parsers⁠

• ⁠@serializers⁠

Documentation is only generated for annotations related to global documentation (a block followed by the "_API" sentinel), request handlers (a block including one of ⁠@get⁠, ⁠@head⁠, ⁠@post⁠, ⁠@put⁠, ⁠@delete⁠, ⁠@connect⁠, ⁠@options⁠, ⁠@trace⁠, ⁠@patch⁠, or ⁠@any⁠), or report generation (a block including ⁠@report⁠)

Examples

# Serve the docs from a different path
api() |>
  api_doc_setting(doc_path = "__man__")

# Add documentation to the api programmatically
api() |>
  api_doc_add(openapi(
    info = openapi_info(
      title = "My awesome api",
      version = "1.0.0"
    )
  ))

# Add documentation to a subset of the docs
api() |>
  api_doc_add(
    openapi_operation(
      summary = "Get the current date",
      responses = list(
        "200" = openapi_response(
          description = "Current Date",
          content = openapi_content(
            "text/plain" = openapi_schema(character())
          )
        )
      )
    ),
    subset = c("paths", "/date", "get")
  )

Set up a plumber2 api to act as a reverse proxy

Description

You can set up your plumber2 api to act as reverse proxy and forward all requests to a specific path (and it's subpaths) to a different URL. In contrast to api_shiny(), api_forward() is not responsible for launching whatever service is being proxied so this should be handled elsewhere. The path will be stripped from the request before being forwarded to the url, meaning that if you set up a proxy on ⁠my/proxy/⁠ to ⁠http://example.com⁠, then a request for my/proxy/user/thomas will end at ⁠http://example.com/user/thomas⁠. Proxying is most useful when forwarding to internal servers though you are free to forward to public URLs as well. However, for the later you'd usually use a redirect instead (via api_redirect())

Usage

api_forward(api, path, url, except = NULL)

Arguments

Value

This functions return the api object allowing for easy chaining with the pipe

Using annotation

You can set up a reverse proxy in your annotated route file using the ⁠@forward⁠ tag

#* @forward /proxy http://127.0.0.1:56789
NULL

Examples

# Serve wikipedia directly from your app
api() |>
  api_forward("my_wiki/", "https://www.wikipedia.org")

Set logging function and access log format for the API

Description

plumber2 has a build-in logging facility that takes care of logging any conditions that are caught, as well as access logs. Further it is possible to log custom messages using the log() method on the api object. However, the actual logging is handled by a customizable function that can be set. You can read more about the logging infrastructure in the fiery documentation. plumber2 reexports the loggers provided by fiery so they are immediately available to the user.

Usage

api_logger(api, logger = NULL, access_log_format = NULL)

logger_null()

logger_console(format = "{time} - {event}: {message}")

logger_file(file, format = "{time} - {event}: {message}")

logger_logger(default_level = "INFO")

logger_switch(..., default = logger_null())

common_log_format

combined_log_format

Arguments

Using annotation

Logger setup doesn't have a dedicated annotation tag, but you can set it up in a ⁠@plumber⁠ block

#* @plumber
function(api) {
  api |>
    api_logger(logger = logger_null())
}

Examples

# Use a different access log format
api() |>
  api_logger(access_log_format = combined_log_format)

# Turn off logging
api() |>
  api_logger(logger_null())

Add a handler to a WebSocket message

Description

WebSockets is a bidirectional communication channel that can be established at the request of the client. While websocket communication is not really part of a standard REST api, it has many uses and can easily be used together with one.

Usage

api_message(api, handler, async = NULL, then = NULL)

Arguments

Details

A handler for a websocket message is much simpler than for requests in general since it doesn't have to concern itself with methods, paths, and responses. Any message handler registered will get called in sequence when a websocket message is recieved from a client. Still, a few expectations apply

Handler Arguments

The handler can take any of the following arguments:

• message: Either a raw vector if the message recieved is in binary form or a single string, giving the message sent from the client

• server: The Plumber2 object representing your server implementation

• client_id: A string uniquely identifying the session the request comes from

• request: The request that was initially used to establish the websocket connection with the client as a reqres::Request object

Handler Return Value

It is not expected that a websocket message sends a response and thus the handler is not required to do anything like that. However, if the handler returns either a raw vector or a single string it is taken as a signal to send this back to the client. Any other return value is silently ignored.

Value

This functions return the api object allowing for easy chaining with the pipe

Async

You can handle websocket messages asynchronously if needed. Like with request handlers you can either do it manually by creating and returning a promise inside the handler, or by letting plumber2 convert your handler to an async handler using the async argument. Due to the nature of promises a handler being converted to a promise can't take request and server arguments, so if you need to manipulate these you need to use then (more on this shortly). The same conventions about return value holds for async message handlers as for regular ones.

Async chaining

Because you can't manipulate request or server in the async handler it may be needed to add operations to perform once the async handler has finished. This can be done through the then argument. This takes a list of functions to chain to the promise using promises::then(). Before the then chain is executed the return value of the async handler will be send back to the client if it is a string or a raw vector. Each then call will receive the same arguments as a standard message handler as well as result which will hold the return value of the previous handler in the chain. For the first then call result will be whatever the main async handler returned. The return value of the last call in the chain will be silently ignored.

Using annotation

A websocket message handler can be added to an API in an annotated route file by using the ⁠@message⁠ tag

#* @message
function(message) {
  if (message == "Hello") {
    return("Hello, you...")
  }
}

You can create async handlers with then chaining using annotation, through the ⁠@async⁠ and ⁠@then⁠ tags

#* @message
#* @async
function(message) {
  if (message == "Hello") {
    return("Hello, you...")
  }
}
#* @then
function(server) {
  server$log("message", "websocket message received")
}

Examples

api() |>
  api_message(
    function(message) {
      if (message == "Hello") {
        return("Hello, you...")
      }
    }
  )

Add a handler to an event

Description

During the life cycle of a plumber API various events will be fired, either automatically or manually. See the article on events in fiery for a full overview. api_on() allows you to add handlers that are called when specific events fire. api_off() can be used to remove the handler if necessary

Usage

api_on(api, event, handler, id = NULL)

api_off(api, id)

Arguments

Value

These functions return the api object allowing for easy chaining with the pipe

Using annotation

Event handler setup doesn't have a dedicated annotation tag, but you can set it up in a ⁠@plumber⁠ block

#* @plumber
function(api) {
  api |>
    api_on("cycle-end", function(server) {
      server$log("message", "tick-tock")
    })
}

Examples

# Add a small console log to show the api is alive
pa <- api() |>
  api_on("cycle-end", function(server) {
    server$log("message", "tick-tock")
  }, id = "lifesign")

# Remove it again
pa |>
  api_off("lifesign")

Load up an API distributed with a package

Description

Packages can included one or more api specification(s) by storing the annotated route files and/or ⁠_server.yml⁠ file in subfolders of ./inst/plumber2. The name of the subfolder will be the name of the api

Usage

api_package(package = NULL, name = NULL, ...)

Arguments

Value

If package or name is NULL then a data frame providing available apis filtered on either package or name (if any is provided) is returned. Otherwise a Plumber2 object representing the api is returned

Examples

# Load one of the plumber2 examples
api_package("plumber2", "quickstart")

# List all available apis
api_package()

Redirect request to another resource

Description

While it is optimal that an API remains stable over its lifetime it is often not fully attainable. In order to direct requests for resources that has been moved to the new location you can add a redirect that ensures a smooth transition for clients still using the old path. Depending on the value of permanent the redirect will respond with a ⁠307 Temporary Redirect⁠ or ⁠308 Permanent Redirect⁠. from and to can contain path parameters and wildcards which will be matched between the two to construct the correct redirect path. Further, to can either be a path to the same server or a fully qualified URL to redirect requests to another server alltogether.

Usage

api_redirect(api, method, from, to, permanent = TRUE)

Arguments

Value

This functions return the api object allowing for easy chaining with the pipe

Using annotation

You can specify redirects in an annotated plumber file using the ⁠@redirect⁠ tag. Preceed the method with a ! to mark the redirect as permanent

#* @redirect !get /old/data/* /new/data/*
#* @redirect any /unstable/endpoint /stable/endpoint
NULL

Examples

api() |>
  api_redirect("get", "/old/data/*", "/new/data/*")

Add a handler for a request

Description

This family of functions facilitates adding a request handler for a specific HTTP method and path.

Usage

api_get(
  api,
  path,
  handler,
  serializers = NULL,
  parsers = NULL,
  use_strict_serializer = FALSE,
  download = FALSE,
  async = FALSE,
  then = NULL,
  doc = NULL,
  route = NULL
)

api_head(
  api,
  path,
  handler,
  serializers = NULL,
  parsers = NULL,
  use_strict_serializer = FALSE,
  download = FALSE,
  async = FALSE,
  then = NULL,
  doc = NULL,
  route = NULL
)

api_post(
  api,
  path,
  handler,
  serializers = NULL,
  parsers = NULL,
  use_strict_serializer = FALSE,
  download = FALSE,
  async = FALSE,
  then = NULL,
  doc = NULL,
  route = NULL
)

api_put(
  api,
  path,
  handler,
  serializers = NULL,
  parsers = NULL,
  use_strict_serializer = FALSE,
  download = FALSE,
  async = FALSE,
  then = NULL,
  doc = NULL,
  route = NULL
)

api_delete(
  api,
  path,
  handler,
  serializers = NULL,
  parsers = NULL,
  use_strict_serializer = FALSE,
  download = FALSE,
  async = FALSE,
  then = NULL,
  doc = NULL,
  route = NULL
)

api_connect(
  api,
  path,
  handler,
  serializers = NULL,
  parsers = NULL,
  use_strict_serializer = FALSE,
  download = FALSE,
  async = FALSE,
  then = NULL,
  doc = NULL,
  route = NULL
)

api_options(
  api,
  path,
  handler,
  serializers = NULL,
  parsers = NULL,
  use_strict_serializer = FALSE,
  download = FALSE,
  async = FALSE,
  then = NULL,
  doc = NULL,
  route = NULL
)

api_trace(
  api,
  path,
  handler,
  serializers = NULL,
  parsers = NULL,
  use_strict_serializer = FALSE,
  download = FALSE,
  async = FALSE,
  then = NULL,
  doc = NULL,
  route = NULL
)

api_patch(
  api,
  path,
  handler,
  serializers = NULL,
  parsers = NULL,
  use_strict_serializer = FALSE,
  download = FALSE,
  async = FALSE,
  then = NULL,
  doc = NULL,
  route = NULL
)

api_any(
  api,
  path,
  handler,
  serializers = NULL,
  parsers = NULL,
  use_strict_serializer = FALSE,
  download = FALSE,
  async = FALSE,
  then = NULL,
  doc = NULL,
  route = NULL
)

Arguments

Value

These functions return the api object allowing for easy chaining with the pipe

Using annotation

Handlers can be specified in an annotated route file using one of the method tags followed by the path it pertains to. You can use various tags to descripe the handler and these will automatically be converted to OpenAPI documentation. Further, additional tags allow you to modify the behaviour of the handler, reflecting the arguments available in the functional approach.

#* A handler for /user/<username>
#*
#* @param username:string The name of the user to provide information on
#*
#* @get /user/<username>
#*
#* @response 200:{name:string, age:integer, hobbies:[string]} Important
#* information about the user such as their name, age, and hobbies
#*
function(username) {
  find_user_in_db(username)
}

Handlers can be specified in an annotated route file using one of the method tags followed by the path it pertains to. You can use various tags to descripe the handler and these will automatically be converted to OpenAPI documentation. Further, additional tags allow you to modify the behaviour of the handler, reflecting the arguments available in the functional approach.

#* A handler for /user/<username>
#*
#* @param username:string The name of the user to provide information on
#*
#* @get /user/<username>
#*
#* @response 200:{name:string, age:integer, hobbies:[string]} Important
#* information about the user such as their name, age, and hobbies
#*
function(username) {
  find_user_in_db(username)
}

You can create async handlers with then chaining using annotation, through the ⁠@async⁠ and ⁠@then⁠ tags

#* A handler for /user/<username>
#*
#* @param username:string The name of the user to provide information on
#*
#* @get /user/<username>
#*
#* @response 200:{name:string, age:integer, hobbies:[string]} Important
#* information about the user such as their name, age, and hobbies
#*
#* @async
function(username) {
  find_user_in_db(username)
}
#* @then
function(server, response) {
  server$log("message", "async operation completed")
  response$set_header("etag", "abcdef")
  Next
}

HTTP Methods

The HTTP specs provide a selection of specific methods that clients can send to the server (your plumber api). While there is no enforcement that the server follows any conventions you should strive to create a server API that adheres to common expectations. It is not required that a server understands all methods, most often the opposite is true. The HTTP methods are described below, but consider consulting MDN to get acquainted with the HTTP spec in general

• GET: This method is used to request specific content and is perhaps the most ubiquitous method in use. GET requests should only retrieve data and should not contain any body content

• HEAD: This method is identical to GET, except the response should only contain headers, no body. Apart from this it is expected that a HEAD request is identical to a GET request for the same resource

• POST: This method delivers content, in the form of a request body, to the server, potentially causing a change in the server. In the context of plumber2 it is often used to call functions that require input larger than what can be put in the URL

• PUT: This method is used to update a specific resource on the server. In the context of a standard plumber2 server this is rarely relevant, though usage can come up. PUT is considered by clients to be indemptotent meaning that sending the same PUT request multiple times have no effect

• DELETE: This method deletes a resource and is the opposite to PUT. As with PUT this method has limited use in most standard plumber2 servers

• CONNECT: This method request the establishment of a proxy tunnel. It is considered advanced use and is very unlikely to have a usecase for your plumber2 api

• OPTIONS: This method is used by clients to query a server about what methods and other settings are supported on a server

• TRACE: This method is a form of ping that should send a response containing the request (stripped of any sensitive information). Many servers disallow this method due to security concerns

• PATCH: This method is like PUT but allows partial modification of a resource

Apart from the above, plumber2 also understands the ANY method which responds to requests to any of the above methods, assuming that a specific handler for the method is not found. As the semantics of the various methods are quite different an ANY handler should mainly be used for rejections or for setting specific broad headers on the response, not as the main handler for the request

The Path

The path defines the URL the request is being made to with the root removed. If your plumber2 server runs from ⁠http://example.com/api/⁠ and a request is made to ⁠http://example.com/api/user/thomas/⁠, then the path would be ⁠user/thomas/⁠. Paths can be static like the prior example, or dynamic as described below:

Path arguments

Consider you have a bunch of users. It would be impractical to register a handler for each one of them. Instead you can use a dynamic path like with the following syntax: ⁠user/<username>/⁠. This path would be matched to any requests made to ⁠user/..something../⁠. The actual value of ..something.. (e.g. thomas) would be made available to the handler (see below). A path can contain multiple arguments if needed, such as ⁠user/<username>/settings/<setting>/⁠

Path wildcards

Apart from path arguments it is also possible to be even less specific by adding a wildcard to the path. The path ⁠user/*⁠ will match both ⁠user/thomas/⁠, ⁠user/thomas/settings/interests/⁠, and anything other path that begins with ⁠user/⁠. As with arguments a path can contain multiple wildcards but the use of these have very diminishing returns. Contrary to path arguments the value(s) corresponding to * is not made available to the handler.

Path Priority

With the existence of path arguments and wildcards it is possible that multiple handlers in a route can be matched to a single request. Since only one can be selected we need to determine which one wins. The priority is based on the specificity of the path. Consider a server containing the following handler paths: ⁠user/thomas/⁠, ⁠user/<username>/⁠, ⁠user/<username>/settings/<setting>/⁠, ⁠user/*⁠. These paths will have the following priority:

1. ⁠user/<username>/settings/<setting>/⁠

2. ⁠user/thomas/⁠

3. ⁠user/<username>/⁠

4. ⁠user/*⁠

The first spot is due to the fact that it is the path with the most elements so it is deemed most specific. For the remaining 3 they all have the same number of elements, but static paths are considered more specific than dynamic paths, and path arguments are considered more specific than wildcards.

A request made to user/carl will thus end up in the third handler, while a request made to user/thomas will end up in the second. This ordering makes it possible to both provide default handlers as well as specialisations for specific paths.

The Handler

The handler is a standard R function that is called when a request is made that matches the handlers path (unless a more specific handler path exists — see above). A handler function can perform any operation a normal R function can do, though you should consider strongly the security implications of your handler functions. However, there are certain expectations in plumber around the arguments a handler function takes and the return value it provides

Handler Arguments

The handler function can take one or more of the following arguments.

• Path arguments: Any path arguments are passed on to the handler. If a handler is registered for the following path ⁠user/<username>/settings/<setting>/⁠ and it handles a request to ⁠user/thomas/settings/interests/⁠ then it will be called with ⁠username = "thomas", setting = "interest"⁠

• request: The request the handler is responding to as a reqres::Request object

• response: The response being returned to the client as a reqres::Response object

• server: The Plumber2 object representing your server implementation

• client_id: A string uniquely identifying the session the request comes from

• query: A list giving any additional arguments passed into the handler as part of the url query string

• body: The request body, parsed as specified by the provided parsers

Handler Return Value

Handlers can return a range of different value types, which will inform plumber2 what to do next:

Returning Next or Break

These two control objects informs plumber2 to either proceed handling the request (Next) or return the response as is, circumventing any remaining routes (Break)

Returning NULL or the response object

This is the same as returning Next, i.e. it signals that handling can proceed

Returning a ggplot2 object

If you return a ggplot2 object it will get plotted for you (and added to the response assuming a graphics serializer is provided) before handling continues

Returning any other value

Any kind of value returned that is not captured by the above description will be set to the response body (overwriting what was already there) and handling is then allowed to continue

Handler conditions

Like any function in R, a handler may need to signal that something happened, either by throwing an error or warning or by emitting a message. You can use stop(), warning(), and message() as you are used to. For all of them, the condition message will end up in the log. Further, for stop() any further handling of the request will end and a ⁠500 Internal Error⁠ response is returned. To take more control over problems you can use the abort_*() family of conditions from reqres. Like stop() they will halt any further processing, but they also allow control over what kind of response is sent back, what kind of information about the issue is communicated to the client, and what kind of information is logged internally. The response they send back (except for abort_status()) all adhere to the HTTP Problem spec defined in RFC 9457.

While it may feel like a good idea to send a detailed error message back to the client it is often better to only inform the client of what they need to change to solve the issue. Too much information about internal implementation details can be a security risk and forwarding internal errors to a client can help inform the client about how the server has been implemented.

Async handling

plumber2 supports async handling of requests in one of two ways:

1. The handler you provide returns a promise object

2. You set async = TRUE (or the name of a registered async evaluator) when adding the handler

For 1), there is no more to do. You have full custody over the created promise and any then()-chaining that might be added to it. For 2) it is a bit different. In that case you provide a regular function and plumber2 takes care of converting it to a promise. Due to the nature of promises a handler being converted to a promise can't take request, response, and server arguments, so if you need to manipulate these you need to use then (more on this shortly). The async handler should yield the value that the response should ultimately get assigned to the body or have plotting side effects (in which case the plot will get added to the response).

Async chaining

Because you can't manipulate request response, or server in the async handler it may be needed to add operations to perform once the async handler has finished. This can be done through the then argument (or using the ⁠@then⁠ tag in annotated route files). This takes a list of functions to chain to the promise using promises::then(). Before the then chain is executed the response will get the return value of the main handler asigned to the body. Each then call will receive the same arguments as a standard request handler as well as result which will hold the return value of the previous handler in the chain. For the first then call result will be a boolean signalling if the async handler wants request handling to proceed to the next route or terminate early. The last call in the chain must return Next or Break to signal if processing should be allowed to continue to the next route.

See Also

Other Request Handlers: api_request_header_handlers

Examples

# Standard use
api() |>
  api_get("/hello/<name:string>", function(name) {
    list(
      msg = paste0("Hello ", name, "!")
    )
  })

# Specify serializers
api() |>
  api_get(
    "/hello/<name:string>",
    function(name) {
      list(
        msg = paste0("Hello ", name, "!")
      )
    },
    serializers = get_serializers(c("json", "xml"))
  )

# Request a download and make it async
api() |>
  api_get(
    "/the_plot",
    function() {
      plot(1:10, 1:10)
    },
    serializers = get_serializers(c("png", "jpeg")),
    download = TRUE,
    async = TRUE
  )

Add a handler for a request header

Description

These handlers are called before the request body has been recieved and lets you preemptively reject requests before recieving their full content. If the handler does not return Next then the request will be returned at once. Most of your logic, however, will be in the main handlers and you are asked to consult the api_request_handlers docs for in-depth details on how to use request handlers in general.

Usage

api_get_header(
  api,
  path,
  handler,
  serializers = NULL,
  parsers = NULL,
  use_strict_serializer = FALSE,
  download = FALSE,
  async = FALSE,
  then = NULL,
  route = NULL
)

api_head_header(
  api,
  path,
  handler,
  serializers = NULL,
  parsers = NULL,
  use_strict_serializer = FALSE,
  download = FALSE,
  async = FALSE,
  then = NULL,
  route = NULL
)

api_post_header(
  api,
  path,
  handler,
  serializers = NULL,
  parsers = NULL,
  use_strict_serializer = FALSE,
  download = FALSE,
  async = FALSE,
  then = NULL,
  route = NULL
)

api_put_header(
  api,
  path,
  handler,
  serializers = NULL,
  parsers = NULL,
  use_strict_serializer = FALSE,
  download = FALSE,
  async = FALSE,
  then = NULL,
  route = NULL
)

api_delete_header(
  api,
  path,
  handler,
  serializers = NULL,
  parsers = NULL,
  use_strict_serializer = FALSE,
  download = FALSE,
  async = FALSE,
  then = NULL,
  route = NULL
)

api_connect_header(
  api,
  path,
  handler,
  serializers = NULL,
  parsers = NULL,
  use_strict_serializer = FALSE,
  download = FALSE,
  async = FALSE,
  then = NULL,
  route = NULL
)

api_options_header(
  api,
  path,
  handler,
  serializers = NULL,
  parsers = NULL,
  use_strict_serializer = FALSE,
  download = FALSE,
  async = FALSE,
  then = NULL,
  route = NULL
)

api_trace_header(
  api,
  path,
  handler,
  serializers = NULL,
  parsers = NULL,
  use_strict_serializer = FALSE,
  download = FALSE,
  async = FALSE,
  then = NULL,
  route = NULL
)

api_patch_header(
  api,
  path,
  handler,
  serializers = NULL,
  parsers = NULL,
  use_strict_serializer = FALSE,
  download = FALSE,
  async = FALSE,
  then = NULL,
  route = NULL
)

api_any_header(
  api,
  path,
  handler,
  serializers = NULL,
  parsers = NULL,
  use_strict_serializer = FALSE,
  download = FALSE,
  async = FALSE,
  then = NULL,
  route = NULL
)

Arguments

Value

These functions return the api object allowing for easy chaining with the pipe

Using annotation

Adding request header handler is done in the same way as for standard request handlers. The only difference is that you include a ⁠@header⁠ tag as well. It is not normal to document header requests as they usually exist as internal controls. You can add ⁠@noDoc⁠ to avoid generating OpenAPI docs for the handler

#* A header handler authorizing users
#*
#* @get /*
#*
#* @header
#* @noDoc
function(client_id, response) {
  if (user_is_allowed(username)) {
    Next
  } else {
    response$status <- 404L
    Break
  }
}

See Also

Other Request Handlers: api_request_handlers

Examples

# Simple size limit (better to use build-in functionality)
api() |>
  api_post_header(
    "/*",
    function(request, response) {
      if (request$get_header("content-type") > 1024) {
        response$status <- 413L
        Break
      } else {
        Next
      }
    }
  )

Launch the API

Description

This function starts the api with the settings it has defined.

Usage

api_run(
  api,
  host = NULL,
  port = NULL,
  block = !is_interactive(),
  showcase = is_interactive(),
  ...,
  silent = FALSE
)

api_stop(api)

Arguments

Value

These functions return the api object allowing for easy chaining with the pipe, even though they will often be the last part of the chain

Examples

pa <- api() |>
  api_get("/", function() {
    list(msg = "Hello World")
  }) |>
  api_on("start", function(...) {
    cat("I'm alive")
  })

# Start the server
pa |> api_run(block = FALSE)

# Stop it again
pa |> api_stop()

Set up CORS for a path in your plumber2 API

Description

This function adds Cross-Origin Resource Sharing (CORS) to a path in your API. The function can be called multiple times to set up CORS for multiple paths, potentially with different settings for each path. CORS is a complex specification and more can be read about it at the CORS plugin documentation.

Usage

api_security_cors(
  api,
  path = "/*",
  origin = "*",
  methods = c("get", "head", "put", "patch", "post", "delete"),
  allowed_headers = NULL,
  exposed_headers = NULL,
  allow_credentials = FALSE,
  max_age = NULL
)

Arguments

Value

This functions return the api object allowing for easy chaining with the pipe

Using annotation

To add CORS to a path you can add ⁠@cors <origin>⁠ to a handler annotation. ⁠<origin>⁠ must be one or more URLs or *, separated by comma (meaning it is not possible to provide a function using the annotation). This will add CORS to all endpoints described in the block. The annotation doesn't allow setting allowed_headers, exposed_headers, allow_credentials or max_age and the default values will be used.

#* A handler for /user/<username>
#*
#* @param username:string The name of the user to provide information on
#*
#* @get /user/<username>
#*
#* @response 200:{name:string, age:integer, hobbies:[string]} Important
#* information about the user such as their name, age, and hobbies
#*
#* @cors https://example.com, https://another-site.com
#*
function(username) {
  find_user_in_db(username)
}

See Also

Other security features: api_security_headers(), api_security_resource_isolation()

Examples

# Set up cors for your asset/ path for the https://examples.com origin

api() |>
  api_security_cors(
    path = "asset/*",
    origin = "https://examples.com"
  )

Add various security related headers to your plumber2 API

Description

This function adds the SecurityHeaders plugin to your plumber2 API. Please consult the documentation for the plugin for up-to-date information on its behaviour.

Usage

api_security_headers(
  api,
  content_security_policy = csp(default_src = "self", script_src = "self",
    script_src_attr = "none", style_src = c("self", "https:", "unsafe-inline"), img_src =
    c("self", "data:"), font_src = c("self", "https:", "data:"), object_src = "none",
    base_uri = "self", form_action = "self", frame_ancestors = "self",
    upgrade_insecure_requests = TRUE),
  content_security_policy_report_only = NULL,
  cross_origin_embedder_policy = NULL,
  cross_origin_opener_policy = "same-origin",
  cross_origin_resource_policy = "same-origin",
  origin_agent_cluster = TRUE,
  referrer_policy = "no-referrer",
  strict_transport_security = sts(max_age = 63072000, include_sub_domains = TRUE),
  x_content_type_options = TRUE,
  x_dns_prefetch_control = FALSE,
  x_download_options = TRUE,
  x_frame_options = "SAMEORIGIN",
  x_permitted_cross_domain_policies = "none",
  x_xss_protection = FALSE
)

Arguments

Value

This functions return the api object allowing for easy chaining with the pipe

Using annotation

Security headers doesn't have a dedicated annotation tag, but you can set it up in a ⁠@plumber⁠ block

#* @plumber
function(api) {
  api |>
    api_security_headers()
}

See Also

Other security features: api_security_cors(), api_security_resource_isolation()

Examples

# Add default security headers to an API
api() |>
  api_security_headers()

Set up resource isolation for a path

Description

This function adds resource isolation to a path in your API. The function can be called multiple times to set up resource isolation for multiple paths, potentially with different settings for each path. You can read in depth about resource isolation at the ResourceIsolation plugin documentation.

Usage

api_security_resource_isolation(
  api,
  path = "/*",
  allowed_site = "same-site",
  forbidden_navigation = c("object", "embed"),
  allow_cors = TRUE
)

Arguments

Value

This functions return the api object allowing for easy chaining with the pipe

Using annotation

To add resource isolation to a path you can add ⁠@rip <allowed_site>⁠ to a handler annotation. This will add resource isolation to all endpoints described in the block. The annotation doesn't allow setting forbidden_navigation or allow_cors and the default values will be used.

#* A handler for /user/<username>
#*
#* @param username:string The name of the user to provide information on
#*
#* @get /user/<username>
#*
#* @response 200:{name:string, age:integer, hobbies:[string]} Important
#* information about the user such as their name, age, and hobbies
#*
#* @rip same-origin
#*
function(username) {
  find_user_in_db(username)
}

See Also

Other security features: api_security_cors(), api_security_headers()

Examples

# Set up resource isolation for everything inside a user path
api() |>
  api_security_resource_isolation(
    path = "<user>/*"
  )

Turn on session cookie data storage for your API

Description

If you need to keep data between requests, but don't want to store it server-side (see api_datastore()) you can instead pass it back and forth as an encrypted session cookie. This function sets it up on your api and after it's use you can now access and set session data in the request and response ⁠$session⁠ field. Be aware that session data is send back and forth with all requests and should thus be kept minimal to avoid congestion on your server.

Usage

api_session_cookie(
  api,
  key,
  name = "reqres",
  expires = NULL,
  max_age = NULL,
  path = NULL,
  secure = NULL,
  same_site = NULL
)

Arguments

Value

These functions return the api object allowing for easy chaining with the pipe

Using annotation

Session cookie setup doesn't have a dedicated annotation tag, but you can set it up in a ⁠@plumber⁠ block

#* @plumber
function(api) {
  api |>
    api_session_cookie(keyring::key_get("my_secret_plumber_key"))
}

Examples

key <- reqres::random_key()

api() |>
  api_session_cookie(key, secure = TRUE) |>
  api_get("/", function(request) {
    if (isTRUE(request$session$foo)) {
      msg <- "You've been here before"
    } else {
      msg <- "You must be new here"
      request$session$foo <- TRUE
    }
    list(
      msg = msg
    )
  })

Serve a Shiny app from a plumber2 api

Description

You can serve one or more shiny apps as part of a plumber2 api. The shiny app launches in a background process and the api will work as a reverse proxy to forward requests to path to the process and relay the response to the client. The shiny app is started along with the api and shut down once the api is stopped. This functionality requires the shiny and callr packages to be installed. Be aware that all requests to subpaths of path will be forwarded to the shiny process, and thus not end up in your normal route

Usage

api_shiny(api, path, app, except = NULL)

Arguments

Value

This functions return the api object allowing for easy chaining with the pipe

Using annotation

A shiny app can be served using an annotated route file by using the ⁠@shiny⁠ tag and proceeding the annotation block with the shiny app object

#* @shiny /my_app/
shiny::shinyAppDir("./shiny")

Examples

blank_shiny <- shiny::shinyApp(
  ui = shiny::fluidPage(),
  server = shiny::shinyServer(function(...) {})
)

api() |>
  api_shiny("my_app/", blank_shiny)

Generic for applying information from a plumber2 block to an api

Description

In order to facilitate extensibility of the plumber2 file syntax you can provide your own methods for how to apply information from a plumber2 block to an api.

Usage

apply_plumber2_block(block, api, route_name, root, ...)

Arguments

Value

api, modified

See Also

add_plumber2_tag()

Examples

# Add a method for a fictional "hello_block" that makes the api say hello when
# it starts
apply_plumber2_block.hello_block <- function(block, api, route_name, root, ...) {
  api$on("start", function(...) {
    message("Hello")
  })
  api
}

Async evaluators provided by plumber

Description

These functions support async request handling. You can register your own as well using register_async().

Usage

mirai_async(...)

Arguments

Value

A function taking expr and envir. The former is the expression to evaluate and the latter is an environment with additional variables that should be made available during evaluation

Provided evaluators

• mirai_async() uses mirai::mirai(). It is registered as "mirai". Be aware that for this evaluator to be performant you should start up multiple persistent background processes. See mirai::daemons().

Examples

# Use the default mirai backend by setting `async = TRUE` with a handler

pa <- api() |>
  api_get("/hello/<name:string>", function(name) {
    list(
      msg = paste0("Hello ", name, "!")
    )
  }, async = TRUE)

Create a _server.yml file to describe your API

Description

While you can manually create a plumber2 API by calling api(), you will often need to deploy the api somewhere else. To facilitate this you can create a ⁠_server.yml⁠ that encapsulates all of your settings and plumber files. If you call api() with a path to such a file the API will be constructed according to its content.

Usage

create_server_yml(..., path = ".", constructor = NULL, freeze_opt = TRUE)

Arguments

Examples

create_server_yml(
  "path/to/a/plumber/file.R"
)

Create a graphics device formatter

Description

This internal function facilitates creating a formatter that uses a specific device for rendering.

Usage

device_formatter(dev_open, dev_close = grDevices::dev.off())

Arguments

Value

A device formatter function

Examples

# Create a png formatter using the default png device
device_formatter(png)

Retrieve options for creating a plumber2 api

Description

You can provide options for your plumber2 api which will be picked up when you create the API with api(). Options can be set either through the internal options() functionality, or by setting environment variables. In the former case, the name of the option must be prefixed with "plumber2.", in the latter case the variable name must be in upper case and prefixed with "PLUMBER2_". If the option is stored as an environment variable then the value is cast to the type giving in default. See the docs for api() for the default values of the different options.

Usage

get_opts(x, default = NULL)

all_opts()

Arguments

Value

For get_opts The value of x, if any, or default. For all_opts() a named list of all the options that are set

Examples

# Using `options()`
old_opts <- options(plumber2.port = 9889L)
get_opts("port")
options(old_opts)

# Using environment variables
old_env <- Sys.getenv("PLUMBER2_PORT")
Sys.setenv(PLUMBER2_PORT = 9889)

## If no default is provided the return value is a string
get_opts("port")

## Provide a default to hint at the options type
get_opts("port", 8080L)

Sys.setenv(PLUMBER2_PORT = old_env)

Formatter orchestration

Description

These functions are for internal use and only exported to ease async evaluation

Usage

init_formatter(formatter)

close_formatter(formatter, info)

clean_formatter(formatter, info)

with_formatter(expr, formatter, info)

Arguments

Value

init_formatter() returns a opaque structure capturing information used by the other functions. close_formatter() may return a value that should be used as response body. with_formatter() returns the result of expr. clean_formatter() is called for it's side effects and should only be called if close_formatter() never evaluated.

Construct OpenAPI specifications

Description

These helper functions aid in constructing OpenAPI compliant specifications for your API. The return simple lists and you may thus forego these helpers and instead construct it all manually (or import it from a json or yaml file). The purpose of these helpers is mainly in basic input checking and for documenting the structure. Read more about the spec at https://spec.openapis.org/oas/v3.0.0.html

Usage

openapi(
  openapi = "3.0.0",
  info = openapi_info(),
  paths = list(),
  tags = list()
)

openapi_info(
  title = character(),
  description = character(),
  terms_of_service = character(),
  contact = openapi_contact(),
  license = openapi_license(),
  version = character()
)

openapi_contact(name = character(), url = character(), email = character())

openapi_license(name = character(), url = character())

openapi_path(
  summary = character(),
  description = character(),
  get = openapi_operation(),
  put = openapi_operation(),
  post = openapi_operation(),
  delete = openapi_operation(),
  options = openapi_operation(),
  head = openapi_operation(),
  patch = openapi_operation(),
  trace = openapi_operation(),
  parameters = list()
)

openapi_operation(
  summary = character(),
  description = character(),
  operation_id = character(),
  parameters = list(),
  request_body = openapi_request_body(),
  responses = list(),
  tags = character()
)

openapi_parameter(
  name = character(),
  location = c("path", "query", "header", "cookie"),
  description = character(),
  required = logical(),
  schema = openapi_schema(),
  content = openapi_content(),
  ...
)

openapi_header(description = character(), schema = openapi_schema())

openapi_schema(x, default = NULL, min = NULL, max = NULL, ..., required = NULL)

openapi_content(...)

openapi_request_body(
  description = character(),
  content = openapi_content(),
  required = logical()
)

openapi_response(
  description = character(),
  content = openapi_content(),
  headers = list()
)

openapi_tag(name = character(), description = character())

Arguments

Value

A list

Examples

# Create docs for an API with a single endpoint
doc <- openapi(
  info = openapi_info(
    title = "My awesome api",
    version = "1.0.0"
  ),
  paths = list(
    "/hello/{name}" = openapi_path(
      get = openapi_operation(
        summary = "Get a greeting",
        parameters = list(
          openapi_parameter(
            name = "name",
            location = "path",
            description = "Your name",
            schema = openapi_schema(character())
          )
        ),
        responses = list(
          "200" = openapi_response(
            description = "a kind message",
            content = openapi_content(
              "text/plain" = openapi_schema(character())
            )
          )
        )
      )
    )
  )
)

# Add it to an api
api() |>
  api_doc_add(doc)

Parse a plumber file

Description

This function takes care of parsing an annotated plumber file and creating one or more routes, API specs, and a modifier function to be called on the plumber app after the routes have been added. This function does not attach the parsed data to a plumber api, and it is rarely necessary to call it directly.

Usage

parse_plumber_file(path, env = caller_env())

Arguments

Value

A list containing:

• route The main route handling requests according to the parsed file, as a named list of length one

• header_route The route to be attached to header events (fires before the body has been recieved and can be used to prematurely reject requests based on their headers), as a named list of length one

• asset_routes All the asset routes created by ⁠@static⁠ blocks as a named list

• message_handlers All the websocket message handlers created by ⁠@message⁠ blocks, as a list

• api A list giving the OpenAPI spec as parsed from the file

• modifier A single function chaining all the functions from ⁠@plumber⁠ blocks together

Examples

# Parse a plumber file
parse_plumber_file("path/to/my/plumber/file.R")

Parser functions provided by plumber2

Description

These functions cover a large area of potential request body formats. They are all registered to their standard mime types but users may want to use them to register them to alternative types if they know it makes sense.

Usage

parse_csv(...)

parse_octet()

parse_rds(...)

parse_feather(...)

parse_parquet(...)

parse_text(multiple = FALSE)

parse_tsv(...)

parse_yaml(...)

parse_geojson(...)

parse_multipart(parsers = get_parsers())

Arguments

Value

A function accepting a raw vector along with a directives argument that provides further directives from the Content-Type to be passed along

Provided parsers

• parse_csv() uses readr::read_csv() for parsing. It is registered as "csv" for the mime types application/csv, application/x-csv, text/csv, and text/x-csv

• parse_multipart uses webutils::parse_multipart() for the initial parsing. It then goes through each part and tries to find a parser that matches the content type (either given directly or guessed from the file extension provided). If a parser is not found it leaves the value as a raw vector. It is registered as "multi" for the mime type ⁠multipart/*⁠

• parse_octet() passes the raw data through unchanged. It is registered as "octet" for the mime type application/octet-stream

• parse_rds() uses unserialize() for parsing. It is registered as "rds" for the mime type application/rds

• parse_feather() uses arrow::read_feather() for parsing. It is registered as "feather" for the mime types application/vnd.apache.arrow.file and application/feather

• parse_parquet() uses arrow::read_parquet() for parsing. It is registered as "parquet" for the mime type application/vnd.apache.parquet

• parse_text() uses rawToChar() for parsing. It is registered as "text" for the mime types text/plain and ⁠text/*⁠

• parse_tsv() uses readr::read_tsv() for parsing. It is registered as "tsv" for the mime types application/tab-separated-values and text/tab-separated-values

• parse_yaml() uses yaml::yaml.load() for parsing. It is registered as "yaml" for the mime types text/vnd.yaml, application/yaml, application/x-yaml, text/yaml, and text/x-yaml

• parse_geojson() uses geojsonsf::geojson_sf() for parsing. It is registered as "geojson" for the mime types application/geo+json and application/vdn.geo+json

Additional registered parsers

• reqres::parse_json() is registered as "json" for the mime types application/json and text/json

• reqres::parse_queryform() is registered as "form" for the mime type application/x-www-form-urlencoded

• reqres::parse_xml() is registered as "xml" for the mime types application/xml and text/xml

• reqres::parse_html() is registered as "html" for the mime type text/html

See Also

register_parser()

Examples

# You can use parsers directly when adding handlers
pa <- api() |>
  api_post("/hello/<name:string>", function(name, body) {
    list(
      msg = paste0("Hello ", name, "!")
    )
  }, parsers = list("text/csv" = parse_csv()))

Objects exported from other packages

Description

These objects are imported from other packages. Follow the links below to see their documentation.

firesafety

csp, sts

reqres

abort_bad_request, abort_conflict, abort_forbidden, abort_gone, abort_http_problem, abort_internal_error, abort_method_not_allowed, abort_not_acceptable, abort_not_found, abort_status, abort_unauthorized, random_key

Register an async evaluator

Description

plumber supports async request handling in two ways. Either manual by returning a promise from the handler, or automatic through the ⁠@async⁠ tag / async argument in the handler functions. The default evaluator is controlled by the plumber2.async option or the PLUMBER2_ASYNC environment variable.

Usage

register_async(name, fun, dependency = NULL)

show_registered_async()

get_async(name = NULL, ...)

Arguments

Examples

# Register an async evaluator based on future (the provided mirai backend is
# superior in every way so this is for illustrative purpose)
future_async <- function(...) {
  function(expr, envir) {
    promises::future_promise(
      expr = expr,
      envir = envir,
      substitute = FALSE,
      ...
    )
  }
}
register_async("future", future_async, c("promises", "future"))

Register or fetch a parser

Description

plumber2 comes with many parsers that should cover almost all standard use cases. Still you might want to provide some of your own, which this function facilitates.

Usage

register_parser(name, fun, mime_types, default = TRUE)

show_registered_parsers()

get_parsers(parsers = NULL)

Arguments

Details

If you want to register your own parser, then the function you register must be a factory function, i.e. a function returning a function. The returned function must accept two arguments, the first being a raw vector corresponding to the request body, the second being the parsed directives from the request Content-Type header. All arguments to the factory function should be optional.

Value

For get_parsers a named list of parser functions named by their mime types. The order given in parsers is preserved.

See Also

parsers

register_serializer()

Examples

# Register a parser that splits at a character and converts to number
register_parser("comma", function(delim = ",") {
  function(raw, directive) {
    as.numeric(strsplit(rawToChar(raw), delim)[[1]])
  }
}, mime_types = "text/plain", default = FALSE)

Register or fetch a serializer

Description

plumber2 comes with many serializers that should cover almost all standard use cases. Still you might want to provide some of your own, which this function facilitates.

Usage

register_serializer(name, fun, mime_type, default = TRUE)

show_registered_serializers()

get_serializers(serializers = NULL)

Arguments

Details

If you want to register your own serializer, then the function you register must be a factory function, i.e. a function returning a function. The returned function must accept a single argument which is the response body. All arguments to the factory function should be optional.

Value

For get_serializers a named list of serializer functions named by their mime type. The order given in serializers is preserved.

Note

Using the ... will provide remaining graphics serializers if a graphics serializer is explicitely requested elsewhere. Otherwise it will provide the remaining non-graphics serializers. A warning is thrown if a mix of graphics and non-graphics serializers are requested.

See Also

serializers

register_serializer()

Examples

# Add a serializer that deparses the value
register_serializer("deparse", function(...) {
  function(x) {
    deparse(x, ...)
  }
}, mime_type = "text/plain")

Serializer functions provided by plumber2

Description

These functions cover a large area of potential response body formats. They are all registered to their standard mime type but users may want to use them to register them to alternative types if they know it makes sense.

Usage

format_csv(...)

format_tsv(...)

format_rds(version = "3", ascii = FALSE, ...)

format_geojson(...)

format_feather(...)

format_parquet(...)

format_yaml(...)

format_htmlwidget(...)

format_format(..., sep = "\n")

format_print(..., sep = "\n")

format_cat(..., sep = "\n")

format_unboxed(...)

format_png(...)

format_jpeg(...)

format_tiff(...)

format_svg(...)

format_bmp(...)

format_pdf(...)

Arguments

Value

A function accepting the response body

Provided serializers

• format_csv() uses readr::format_csv() for formatting. It is registered as "csv" to the mime type text/csv

• format_tsv() uses readr::format_tsv() for formatting. It is registered as "tsv" to the mime type text/tsv

• format_rds() uses serialize() for formatting. It is registered as "rds" to the mime type application/rds

• format_geojson() uses geojsonsf::sfc_geojson() or geojsonsf::sf_geojson() for formatting depending on the class of the response body. It is registered as "geojson" to the mime type application/geo+json

• format_feather() uses arrow::write_feather() for formatting. It is registered as "feather" to the mime type application/vnd.apache.arrow.file

• format_parquet() uses nanoparquet::write_parquet() for formatting. It is registered as "parquet" to the mime type application/vnd.apache.parquet

• format_yaml() uses yaml::as.yaml() for formatting. It is registered as "yaml" to the mime type text/yaml

• format_htmlwidget() uses htmlwidgets::saveWidget() for formatting. It is registered as "htmlwidget" to the mime type text/html

• format_format() uses format() for formatting. It is registered as "format" to the mime type text/plain

• format_print() uses print() for formatting. It is registered as "print" to the mime type text/plain

• format_cat() uses cat() for formatting. It is registered as "cat" to the mime type text/plain

• format_unboxed() uses reqres::format_json() with auto_unbox = TRUE for formatting. It is registered as "unboxedJSON" to the mime type application/json

Additional registered serializers

• reqres::format_json() is registered as "json" to the mime type application/json

• reqres::format_html() is registered as "html" to the mime type text/html

• reqres::format_xml() is registered as "xml" to the mime type text/xml

• reqres::format_plain() is registered as "text" to the mime type text/plain

Provided graphics serializers

Serializing graphic output is special because it requires operations before and after the handler is executed. Further, handlers creating graphics are expected to do so through side-effects (i.e. call to graphics rendering) or by returning a ggplot2 object. If you want to create your own graphics serializer you should use device_formatter() for constructing it.

• format_png() uses ragg::agg_png() for rendering. It is registered as "png" to the mime type image/png

• format_jpeg() uses ragg::agg_jpeg() for rendering. It is registered as "jpeg" to the mime type image/jpeg

• format_tiff() uses ragg::agg_tiff() for rendering. It is registered as "tiff" to the mime type image/tiff

• format_svg() uses svglite::svglite() for rendering. It is registered as "svg" to the mime type image/svg+xml

• format_bmp() uses grDevices::bmp() for rendering. It is registered as "bmp" to the mime type image/bmp

• format_pdf() uses grDevices::pdf() for rendering. It is registered as "pdf" to the mime type application/pdf

See Also

register_serializer()

Examples

# You can use serializers directly when adding handlers
pa <- api() |>
  api_get("/hello/<name:string>", function(name) {
    list(
      msg = paste0("Hello ", name, "!")
    )
  }, serializers = list("application/json" = format_unboxed()))