Perform a dry run

Source: R/req-dry-run.R

This shows you exactly what httr2 will send to the server, without actually sending anything. It requires the httpuv package because it works by sending the real HTTP request to a local webserver, thanks to the magic of curl::curl_echo().

req_dry_run(
  req,
  quiet = FALSE,
  redact_headers = TRUE,
  testing_headers = is_testing(),
  pretty_json = getOption("httr2_pretty_json", TRUE)
)

Arguments

req

A httr2 request object.

quiet

If TRUE doesn't print anything.

redact_headers

Redact confidential data in the headers? Currently redacts the contents of the Authorization header to prevent you from accidentally leaking credentials when debugging/reprexing.

testing_headers

If TRUE, removes headers that httr2 would otherwise be automatically added, which are likely to change across test runs. This currently includes:

  • The default User-Agent, which varies based on libcurl, curl, and httr2 versions.

  • The `Host“ header, which is often set to a testing server.

  • The Content-Length header, which will often vary by platform because of varying newline encodings. (And is also not correct if you have pretty_json = TRUE.)

  • The Accept-Encoding header, which varies based on how libcurl was built.

pretty_json

If TRUE, automatically prettify JSON bodies.

Value

Invisibly, a list containing information about the request, including method, path, and headers.

Details

Limitations

  • The HTTP version is always HTTP/1.1 (since you can't determine what it will actually be without connecting to the real server).

Examples

# httr2 adds default User-Agent, Accept, and Accept-Encoding headers
request("http://example.com") |> req_dry_run()
#> GET / HTTP/1.1
#> accept: */*
#> accept-encoding: deflate, gzip, br, zstd
#> host: example.com
#> user-agent: httr2/1.1.2 r-curl/7.0.0 libcurl/7.81.0
#> 

# the Authorization header is automatically redacted to avoid leaking
# credentials on the console
req <- request("http://example.com") |> req_auth_basic("user", "password")
req |> req_dry_run()
#> GET / HTTP/1.1
#> accept: */*
#> accept-encoding: deflate, gzip, br, zstd
#> authorization: <REDACTED>
#> host: example.com
#> user-agent: httr2/1.1.2 r-curl/7.0.0 libcurl/7.81.0
#> 

# if you need to see it, use redact_headers = FALSE
req |> req_dry_run(redact_headers = FALSE)
#> GET / HTTP/1.1
#> accept: */*
#> accept-encoding: deflate, gzip, br, zstd
#> authorization: <REDACTED>
#> host: example.com
#> user-agent: httr2/1.1.2 r-curl/7.0.0 libcurl/7.81.0
#>