This class handles all functionality involved in crafting a http response. Much of the functionality is inspired by the Request class in Express.js, so the documentation for this will complement this document. As reqres is build on top of the Rook specifications the Response object can be converted to a compliant list object to be passed on to e.g. the httpuv handler.

# S3 method for Response
as.list(x, ...)




A Response object




A rook-compliant list-response (in case of as.list()) or a logical indicating whether the object is a Response (in case of is.Response())


A Response object is always created as a response to a Request object and contains a reference to the originating Request object. A Response is always initialized with a 404 Not Found code, an empty string as body and the Content-Type header set to text/plain. As the Content-Type header is required for httpuv to function, it will be inferred if missing when converting to a list. If the body is a raw vector it will be set to application/octet-stream and otherwise it will be set to text/plain. It is always advised to consciously set the Content-Type header though. The only exception is when attaching a standard file where the type is inferred from the file extension automatically. Unless the body is a raw vector it will automatically be converted to a character vector and collapsed to a single string with "\n" separating the individual elements before the Response object is converted to a list (that is, the body can exist as any type of object up until the moment where the Response object is converted to a list). To facilitate communication between different middleware the Response object contains a data store where information can be stored during the lifetime of the response.


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


res <- Response$new(request)

But often it will be provided by the request using the respond() method, which will provide the response, creating one if it doesn't exist


res <- request$respond()


requestThe Request object that the Response is responding to


The following fields are accessible in a Response object:


Gets or sets the status code of the response. Is initialised with 404L


Set or get he body of the response. If it is a character vector with a single element named 'file' it will be interpreted as the location of a file. It is better to use the file field for creating a response referencing a file as it will automatically set the correct headers.


Set or get the location of a file that should be used as the body of the response. If the body is not referencing a file (but contains something else) it will return NULL. The Content-Type header will automatically be inferred from the file extension, if known. If unknown it will defaults to application/octet-stream. If the file has no extension it will be text/plain. Existence of the file will be checked.


Get or sets the Content-Type header of the response based on a file extension or mime-type.


Get the original Request object that the object is responding to.


The following methods are available in a Response object:

set_header(name, value)

Sets the header given by name. value will be converted to character. A header will be added for each element in value. Use append_header() for setting headers without overwriting existing ones.


Returns the header(s) given by name


Removes all headers given by name


Test for the existence of any header given by name

append_header(name, value)

Adds an additional header given by name with the value given by value. If the header does not exist yet it will be created.

set_data(key, value)

Adds value to the internal data store and stores it with key


Retrieves the data stored under key in the internal data store.


Removes the data stored under key in the internal data store.


Queries whether the data store has an entry given by key

attach(file, filename=basename(file), type=NULL)

Sets the body to the file given by file and marks the response as a download by setting the Content-Disposition to attachment; filename=<filename>. Use the type argument to overwrite the automatic type inference from the file extension.


Sets the status to code and sets the body to the associated status code description (e.g. Bad Gateway for 502L)

set_cookie(name, value, encode = TRUE, expires = NULL, http_only = NULL, max_age = NULL, path = NULL, secure = NULL, same_site = NULL)

Adds the cookie given by name to the given value, optionally url encoding it, along with any additional directives. See for a description of the different directives. If the cookie already exists it will be overwritten. The validity of the directives will automatically be checked. expires expects a POSIXct object, http_only and secure expect a logical, max_age expects an integer, path a string, and same_site either "Lax" or "Strict"


Removes the cookie named name from the response.


Queries whether the response contains a cookie named name


Sets the Link header based on the named arguments passed to .... The names will be used for the rel directive.

format(..., autofail = TRUE, compress = TRUE)

Based on the formatters passed in through ... content negotiation is performed with request and the preferred formatter is chosen. The Content-Type header is set automatically. If compress = TRUE the compress() method will be called after formatting. If an error is encountered and autofail = TRUE the response will be set to 500. If a formatter is not found and autofail = TRUE the response will be set to 406. If formatting is successful it will return TRUE, if not it will return FALSE

compress(priority = c('gzip', 'deflate', 'br', 'identity'))

Based on the provided priority, an encoding is negotiated with the request and applied. The Content-Encoding header is set to the chosen compression algorithm.


Calculates the length (in bytes) of the body. This is the number that goes into the Content-Length header. Note that the Content-Length header is set automatically by httpuv so this method should only be called if the response size is needed for other reasons.


Converts the object to a list for further processing by a Rook compliant server such as httpuv. Will set Content-Type header if missing and convert a non-raw body to a single character string.

See also

Request for handling http requests


fake_rook <- fiery::fake_request( '', content = 'This is elaborate ruse', headers = list( Accept = 'application/json; text/*', Content_Type = 'text/plain' ) ) req <- Request$new(fake_rook) res <- Response$new(req) res
#> A HTTP response #> =============== #> Status: 404 - Not Found #> Content type: text/plain #> #> In response to:
# Set the body to the associated status text res$status_with_text(200L) res$body
#> [1] "OK"
# Infer Content-Type from file extension res$type <- 'json' res$type
#> [1] "application/json"
# Prepare a file for download res$attach(system.file('DESCRIPTION', package = 'reqres')) res$type
#> [1] "text/plain"
#> file #> "/home/travis/R/Library/reqres/DESCRIPTION"
#> [1] "attachment; filename=DESCRIPTION"
# Cleaning up connections rm(fake_rook, req, res) gc()
#> used (Mb) gc trigger (Mb) max used (Mb) #> Ncells 790553 42.3 1509305 80.7 1224421 65.4 #> Vcells 1522525 11.7 8388608 64.0 2471676 18.9