How can I add a string message to RapidJson Document allocator?

Question

I want to create a JSON message in C++ using RapidJson. So at the end, I want something like:

{"path" : [
    {"position" : {
             "x" : "4",
             "y" : "3"
              },
      "orientation" : {
              "x" : "1"
      }},
    {"position" : {
             "x" : "4",
             "y" : "3"
              },
      "orientation" : {
              "x" : "1"
      }}
    ]
  }

In order to do that in C++, I have written this code:

rapidjson::Document::AllocatorType& allocator = fromScratch.GetAllocator();
std::string ret = "{\"path\" :\" [\"";
for(int i = 0; i<srv.response.plan.poses.size(); i++)
{
    float x = srv.response.plan.poses[i].pose.position.x;
    float y = srv.response.plan.poses[i].pose.position.y;
    float th = srv.response.plan.poses[i].pose.orientation.x;
    std::string pos = "{position:{x:" + std::to_string(x) + ",y:" + std::to_string(y) + "},";
    std::string orient = "{orientation:{x:" + std::to_string(th) + "}}";
    fromScratch.AddMember("position", pos, allocator);
    fromScratch.AddMember("orientation", orient, allocator);
    ret += fromScratch["posiiton"].GetString();
    ret += fromScratch["orientation"].GetString();
    if (i+1 < srv.response.plan.poses.size()) ret += "\",";
    fromScratch.RemoveMember("position");
    fromScratch.RemoveMember("orientation");

}
ret += "]\" }\"";

Basically, srv.response.plan.poses is just an array consisting poses, where poses consists of position and orientation and position has x and y (both floats), same with orientation (only x)

As you can see, I have converted them to strings and tried to add member using rapidjson but I am getting this error:

error: no matching function for call to ‘rapidjson::GenericValue<rapidjson::UTF8<> >::GenericValue(std::__cxx11::basic_string<char>&)’
         GenericValue v(value);

Answer 1

You need to add #define RAPIDJSON_HAS_STDSTRING 1 before including any rapidjson header to be able to use std::string with rapidjson or use std::string::c_str to convert your string to a const char* and add it in your document.