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Perform a request to get a response

Source: R/req-perform.R
req_perform.Rd

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 the response. 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_response>
#> GET https://www.google.com/
#> Status: 200 OK
#> Content-Type: text/html
#> Body: In memory (19036 bytes)