GET request with an empty header

How can I use httr::GET to send empty headers?

The documentation for add_header says:

 ...  named header values. To stop an existing header from being set, pass an empty string: "".

For example, a 'normal' header:

r <- GET("http://httpbin.org/get", add_headers(Name='hadley'))
str(content(r)$headers)

List of 6
 $ Accept         : chr "application/json, text/xml, application/xml, */*"
 $ Accept-Encoding: chr "deflate, gzip"
 $ Host           : chr "httpbin.org"
 $ Name           : chr "hadley"
 $ User-Agent     : chr "libcurl/7.64.1 r-curl/4.3.3 httr/1.4.4"
 $ X-Amzn-Trace-Id: chr "Root=1-63947737-4ad57825480901485249f1f0"

Empty header is not sent because it is unset:

r <- GET("http://httpbin.org/get", add_headers(Name=''))
str(content(r)$headers)

List of 5
 $ Accept         : chr "application/json, text/xml, application/xml, */*"
 $ Accept-Encoding: chr "deflate, gzip"
 $ Host           : chr "httpbin.org"
 $ User-Agent     : chr "libcurl/7.64.1 r-curl/4.3.3 httr/1.4.4"
 $ X-Amzn-Trace-Id: chr "Root=1-63947862-4dddca9d5789c505444e4279"

Using NULL produce the same result (no header is sent) and NA sends 'NA' as a header value. I found a similar issue (though I lost it sorry) with POST, the suggestion was to use encode = 'raw' though this does not solve the issue:


 version  R version 4.2.1 (2022-06-23)
 os       macOS Big Sur 11.6.8
 package     * version    date (UTC) lib source
 askpass       1.1        2019-01-13 [1] CRAN (R 4.2.0)
 cli           3.4.1      2022-09-23 [1] CRAN (R 4.2.0)
 curl          4.3.3      2022-10-06 [1] CRAN (R 4.2.0)
 fuzee       * 0.0.0.1000 2022-11-13 [1] Github (ammaraziz/fuzee@fd4ab8d)
 httr        * 1.4.4      2022-08-17 [1] CRAN (R 4.2.0)
 jsonlite      1.8.3      2022-10-21 [1] CRAN (R 4.2.0)
 openssl       2.0.4      2022-10-17 [1] CRAN (R 4.2.0)
 pacman        0.5.1      2019-03-11 [1] CRAN (R 4.2.0)
 R6            2.5.1      2021-08-19 [1] CRAN (R 4.2.0)
 sessioninfo   1.2.2      2021-12-06 [1] CRAN (R 4.2.0)

r-lib / httr

GET request with an empty header #729