CODEWITHSUNDEEP
c++curllibcurl
muda
muda

Reputation: 23

curl PATCH to update value works as a curl command but not in libcurl c++, any ideas what is wrong?

I am trying to replicate the following curl command in c++ code using the curl library but with no luck. The curl command is (the url is an actual url I am just hiding it):

curl -iX PATCH '*URL*/attrs/topicData' \
-H 'Content-Type: application/json' \
-H 'Link: <http://context-provider:3000/data-models/ngsi-context.jsonld>; rel="http://www.w3.org/ns/json-ld#context"; type="application/ld+json"' \
--data-raw '{
    "value": "Hi, new data test",
    "type": "Property"
}'

This works perfectly fine and updates the value as required. My issues is that I can't replicate it in c++ code. I am using the nlohmann json library just in case that helps.

My c++ code is:

  json ent={
    {"type","Property"},
    {"value","updated successfully"}
  };
  curl_global_init(CURL_GLOBAL_DEFAULT);
  std::string json_entity = ent.dump();
  curl = curl_easy_init();
  if (curl) {
    // Add headers
    struct curl_slist *headers = NULL;
    headers = curl_slist_append(headers, "Content-Type: application/json");
    headers = curl_slist_append(headers, R"(Link: <http://context-provider:3000/data-models/ngsi-context.jsonld>; rel="http://w3.org/ns/json-ld#context"; type="application/ld+json")");
    // Set custom headers
    curl_easy_setopt(curl, CURLOPT_HTTPHEADER, headers);
    // Set URL
    curl_easy_setopt(curl, CURLOPT_URL, "*URL*/attrs/topicData");
    // Set request type
    curl_easy_setopt(curl, CURLOPT_CUSTOMREQUEST, "PATCH");
    // Set values
    curl_easy_setopt(curl, CURLOPT_POSTFIELDS,json_entity);

    // Perform the request which prints to stdout
    result = curl_easy_perform(curl);
    // Error check
    if (result != CURLE_OK) {
      std::cerr << "Error during curl request: " 
                << curl_easy_strerror(result) << std::endl;
    }

    //Free header list
    curl_slist_free_all(headers);

    curl_easy_cleanup(curl);
  }
  else {
    std::cerr << "Error initializing curl." << std::endl;
  }

The error that I am getting is: "type":"http://uri.etsi.org/ngsi-ld/errors/InvalidRequest", "title":"Invalid request.", "details":"Invalid request."

I think my issue is at set values command but I am not sure what the problem is.

Can anyone please advice me on what I am doing wrong?

Upvotes: 2

Views: 3904

Answers (1)

Ted Lyngmo
Ted Lyngmo

Reputation: 117318

CURLOPT_POSTFIELDS expects a char* but you are supplying a std::string.

This should be working better:

curl_easy_setopt(curl, CURLOPT_POSTFIELDS, json_entity.data());

Upvotes: 4

Related Questions