content-types function

Working with content types

The HttpResponse class holds all the responses elements for an HTTP request. This document details how to work specifically with the content-type of the response headers

Content types

The "Content-Type" header in HTTP responses gives the media type of the response. The media type is both the data format and how the data is intended to be processed by a recipient. (modified from rfc7231)

Behavior of the parameters HttpResponse raise_for_ct* methods

• type: (only applicable for the raise_for_ct() method): instead of using one of the three other content type methods for html, json, or xml, you can specify a mime type to check, any of those in mime::mimemap

• charset: if you don't give a value to this parameter, we only check that the content type is what you expect; that is, the charset, if given, is ignored.

• behavior: by default when you call this method, and the content type does not match what the method expects, then we run stop() with a message. Instead of stopping, you can choose behavior="warning"

  and we'll throw a warning instead, allowing any downstream processing to proceed.

Examples

## Not run:

(x <- HttpClient$new(url = "https://hb.opencpu.org"))
(res <- x$get())

## see the content type
res$response_headers

## check that the content type is text/html
res$raise_for_ct_html()

## it's def. not json
# res$raise_for_ct_json()

## give custom content type
res$raise_for_ct("text/html")
# res$raise_for_ct("application/json")
# res$raise_for_ct("foo/bar")

## check charset in addition to the media type
res$raise_for_ct_html(charset = "utf-8")
# res$raise_for_ct_html(charset = "utf-16")

# warn instead of stop
res$raise_for_ct_json(behavior = "warning")
## End(Not run)

References

spec for content types: https://datatracker.ietf.org/doc/html/rfc7231#section-3.1.1.5

spec for media types: https://datatracker.ietf.org/doc/html/rfc7231#section-3.1.1.1

See Also

HttpResponse