req_perform()
will automatically convert HTTP errors (i.e. any 4xx or 5xx
status code) into R errors. Use req_error()
to either override the
defaults, or extract additional information from the response that would
be useful to expose to the user.
Arguments
- req
A request.
- is_error
A predicate function that takes a single argument (the response) and returns
TRUE
orFALSE
indicating whether or not an R error should signalled.- body
A callback function that takes a single argument (the response) and returns a character vector of additional information to include in the body of the error. This vector is passed along to the
message
argument ofrlang::abort()
so you can use any formatting that it supports.
Value
A modified HTTP request.
See also
req_retry()
to control when errors are automatically retried.
Examples
# Performing this request usually generates an error because httr2
# converts HTTP errors into R errors:
req <- request("http://httpbin.org/404")
try(req %>% req_perform())
#> Error in resp_abort(resp, error_body(req, resp)) : HTTP 404 Not Found.
# You can still retrieve it with last_response()
last_response()
#> <httr2_response>
#> GET http://httpbin.org/404
#> Status: 404 Not Found
#> Content-Type: text/html
#> Body: In memory (233 bytes)
# But you might want to suppress this behaviour:
resp <- req %>%
req_error(is_error = function(resp) FALSE) %>%
req_perform()
resp
#> <httr2_response>
#> GET http://httpbin.org/404
#> Status: 404 Not Found
#> Content-Type: text/html
#> Body: In memory (233 bytes)
# Or perhaps you're working with a server that routinely uses the
# wrong HTTP error codes only 500s are really errors
request("http://example.com") %>%
req_error(is_error = function(resp) resp_status(resp) == 500)
#> <httr2_request>
#> GET http://example.com
#> Body: empty
#> Policies:
#> • error_is_error: a function
# Most typically you'll use req_error() to add additional information
# extracted from the response body (or sometimes header):
error_body <- function(resp) {
resp_body_json(resp)$error
}
request("http://example.com") %>%
req_error(body = error_body)
#> <httr2_request>
#> GET http://example.com
#> Body: empty
#> Policies:
#> • error_body: a function
# Learn more in https://httr2.r-lib.org/articles/wrapping-apis.html