req_perform: Perform a request to get a response

In httr2: Perform HTTP Requests and Process the Responses

Perform a request to get a response

Description

After preparing a request, call req_perform() to perform it, fetching the results back to R as a response.

The default HTTP method is GET unless a body (set by req_body_json and friends) is present, in which case it will be POST. You can override these defaults with req_method().

Usage

req_perform(
  req,
  path = NULL,
  verbosity = NULL,
  mock = getOption("httr2_mock", NULL),
  error_call = current_env()
)

Arguments

req	A request.
path	Optionally, path to save body of request. This is useful for large responses since it avoids storing the response in memory.
verbosity	How much information to print? This is a wrapper around req_verbose() that uses an integer to control verbosity: 0: no output 1: show headers 2: show headers and bodies 3: show headers, bodies, and curl status messages. Use with_verbosity() to control the verbosity of requests that you can't affect directly.
mock	A mocking function. If supplied, this function is called with the request. It should return either NULL (if it doesn't want to handle the request) or a response (if it does). See with_mock()/ local_mock() for more details.
error_call	The execution environment of a currently running function, e.g. caller_env(). The function will be mentioned in error messages as the source of the error. See the call argument of abort() for more information.

Value

• If the HTTP request succeeds, and the status code is ok (e.g. 200), an HTTP response.

• If the HTTP request succeeds, but the status code is an error (e.g a 404), an error with class c("httr2_http_404", "httr2_http"). By default, all 400 and 500 status codes will be treated as an error, but you can customise this with req_error().

• If the HTTP request fails (e.g. the connection is dropped or the server doesn't exist), an error with class "httr2_failure".

Requests

Note that one call to req_perform() may perform multiple HTTP requests:

• If the url is redirected with a 301, 302, 303, or 307, curl will automatically follow the Location header to the new location.

• If you have configured retries with req_retry() and the request fails with a transient problem, req_perform() will try again after waiting a bit. See req_retry() for details.

• If you are using OAuth, and the cached token has expired, req_perform() will get a new token either using the refresh token (if available) or by running the OAuth flow.

Progress bar

req_perform() will automatically add a progress bar if it needs to wait between requests for req_throttle() or req_retry(). You can turn the progress bar off (and just show the total time to wait) by setting options(httr2_progress = FALSE).

See Also

req_perform_parallel() to perform multiple requests in parallel. req_perform_iterative() to perform multiple requests iteratively.

Examples

request("https://google.com") |>
  req_perform()

httr2 documentation built on Nov. 14, 2023, 5:08 p.m.