NAME

       CURLOPT_POSTFIELDS - data to POST to server

SYNOPSIS

       #include <curl/curl.h>

       CURLcode curl_easy_setopt(CURL *handle, CURLOPT_POSTFIELDS, char *postdata);

DESCRIPTION

       Pass  a  char  pointer  as  parameter,  pointing to the data buffer to use in an HTTP POST
       operation or an MQTT subscribe. The data must be formatted and encoded the  way  you  want
       the server to receive it. libcurl does not convert or encode it in any way. For example, a
       web server may assume that this data is URL encoded.

       The data pointed to is NOT copied by the library: as a consequence, it must  be  preserved
       by  the  calling application until the associated transfer finishes.  This behavior can be
       changed (so libcurl does copy the data) by  instead  using  the  CURLOPT_COPYPOSTFIELDS(3)
       option.

       This  POST  is  a  normal  application/x-www-form-urlencoded  kind  (and libcurl sets that
       Content-Type by default when this option is used), which is commonly used by  HTML  forms.
       Change Content-Type with CURLOPT_HTTPHEADER(3).

       You  can  use  curl_easy_escape(3)  to  URL  encode  your data, if necessary. It returns a
       pointer to an encoded string that can be passed as postdata.

       Using CURLOPT_POSTFIELDS(3) implies setting CURLOPT_POST(3) to 1.

       If CURLOPT_POSTFIELDS(3) is explicitly set to NULL then libcurl gets the  POST  data  from
       the  read  callback.  To  send a zero-length (empty) POST, set CURLOPT_POSTFIELDS(3) to an
       empty string, or set CURLOPT_POST(3) to 1 and CURLOPT_POSTFIELDSIZE(3) to 0.

       libcurl assumes this option points  to  a  null-terminated  string  unless  you  also  set
       CURLOPT_POSTFIELDSIZE(3)  to  specify  the  length  of  the  provided  data, which then is
       strictly required if you want to send off null bytes included in the data.

       Using POST with HTTP 1.1 implies the use of a "Expect: 100-continue" header,  and  libcurl
       adds that header automatically if the POST is either known to be larger than 1MB or if the
       expected size is unknown. You can disable this header with CURLOPT_HTTPHEADER(3) as usual.

       To make multipart/formdata posts, check out the CURLOPT_MIMEPOST(3) option  combined  with
       curl_mime_init(3).

DEFAULT

       NULL

PROTOCOLS

       This functionality affects http and mqtt

EXAMPLE

       /* send an application/x-www-form-urlencoded POST */
       int main(void)
       {
         CURL *curl = curl_easy_init();
         if(curl) {
           const char *data = "data to send";

           curl_easy_setopt(curl, CURLOPT_URL, "https://example.com");

           /* size of the POST data if strlen() is not good enough */
           curl_easy_setopt(curl, CURLOPT_POSTFIELDSIZE, 12L);

           /* pass in a pointer to the data - libcurl does not copy */
           curl_easy_setopt(curl, CURLOPT_POSTFIELDS, data);

           curl_easy_perform(curl);
         }

         /* send an application/json POST */
         curl = curl_easy_init();
         if(curl) {
           const char *json = "{\"name\": \"daniel\"}";
           struct curl_slist *slist1 = NULL;
           slist1 = curl_slist_append(slist1, "Content-Type: application/json");
           slist1 = curl_slist_append(slist1, "Accept: application/json");

           /* set custom headers */
           curl_easy_setopt(curl, CURLOPT_HTTPHEADER, slist1);

           curl_easy_setopt(curl, CURLOPT_URL, "https://example.com");

           /* pass in a pointer to the data - libcurl does not copy */
           curl_easy_setopt(curl, CURLOPT_POSTFIELDS, json);

           curl_easy_perform(curl);
         }
       }

AVAILABILITY

       Added in curl 7.1

RETURN VALUE

       Returns CURLE_OK

SEE ALSO

       CURLOPT_COPYPOSTFIELDS(3),          CURLOPT_MIMEPOST(3),         CURLOPT_POSTFIELDSIZE(3),
       CURLOPT_READFUNCTION(3), CURLOPT_UPLOAD(3)