Add additional headers to a request.

Wikipedia provides a useful list of common http headers: http://en.wikipedia.org/wiki/List_of_HTTP_header_fields.

add_headers(..., .headers = character())

Arguments

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

See also

accept() and content_type() for convenience functions for setting accept and content-type headers.

Other config: authenticate(), config(), set_cookies(), timeout(), use_proxy(), user_agent(), verbose()

Examples

add_headers(a = 1, b = 2)
#> <request>
#> Headers:
#> * a: 1
#> * b: 2
add_headers(.headers = c(a = "1", b = "2"))
#> <request>
#> Headers:
#> * a: 1
#> * b: 2

GET("http://httpbin.org/headers")
#> Response [http://httpbin.org/headers]
#>   Date: 2020-08-17 22:22
#>   Status: 200
#>   Content-Type: application/json
#>   Size: 284 B
#> {
#>   "headers": {
#>     "Accept": "application/json, text/xml, application/xml, */*", 
#>     "Accept-Encoding": "deflate, gzip", 
#>     "Host": "httpbin.org", 
#>     "User-Agent": "libcurl/7.58.0 r-curl/4.3 httr/1.4.2", 
#>     "X-Amzn-Trace-Id": "Root=1-5f3b0324-324a19d1faa8619291cc07a9"
#>   }
#> }

# Add arbitrary headers
GET(
  "http://httpbin.org/headers",
  add_headers(version = version$version.string)
)
#> Response [http://httpbin.org/headers]
#>   Date: 2020-08-17 22:22
#>   Status: 200
#>   Content-Type: application/json
#>   Size: 332 B
#> {
#>   "headers": {
#>     "Accept": "application/json, text/xml, application/xml, */*", 
#>     "Accept-Encoding": "deflate, gzip", 
#>     "Host": "httpbin.org", 
#>     "User-Agent": "libcurl/7.58.0 r-curl/4.3 httr/1.4.2", 
#>     "Version": "R version 3.6.2 (2019-12-12)", 
#>     "X-Amzn-Trace-Id": "Root=1-5f3b0324-675c7e882f1d2a48d60cc3cf"
#>   }
#> }

# Override default headers with empty strings
GET("http://httpbin.org/headers", add_headers(Accept = ""))
#> Response [http://httpbin.org/headers]
#>   Date: 2020-08-17 22:22
#>   Status: 200
#>   Content-Type: application/json
#>   Size: 217 B
#> {
#>   "headers": {
#>     "Accept-Encoding": "deflate, gzip", 
#>     "Host": "httpbin.org", 
#>     "User-Agent": "libcurl/7.58.0 r-curl/4.3 httr/1.4.2", 
#>     "X-Amzn-Trace-Id": "Root=1-5f3b0324-f43798c8aa0541b831165086"
#>   }
#> }