Read a sub json using boost property tree

I need to read a field in a JSON file which itself is a JSON. I need to read the JSON field in one go. Is there any way available? Sample JSON I am trying to read is provided below.

enter code here
   {
      "responses": [
       { 
          "id": "1",
          "status": 200,
          "headers": {
                 "OData-Version": "4.0",
                 "Content-Type":"application/json;odata.metadata=minimal;odata.streaming=true"
           },
          "body": {        
              "createdDateTime": "2021-04-22T09:24:59.394Z",
              "displayName": "Test1",        
              "visibility": "public",        
              "isMembershipLimitedToOwners": false,
              "discoverySettings": { "showInTeamsSearchAndSuggestions": true },
              "memberSettings": {
              "allowCreateUpdateChannels": true,
              "allowCreateUpdateRemoveConnectors": true
           },
           "guestSettings": {
              "allowCreateUpdateChannels": true,
              "allowDeleteChannels": false
            },
            "messagingSettings": {
              "allowUserEditMessages": true,
              "allowChannelMentions": true
            },
            "funSettings": {
              "allowGiphy": true,
              "allowCustomMemes": true
            }
          }    }  ]
        }

I am trying to read the "body" field using the code below (json is read in boost::property_tree::ptree jsonBatchResponse jsonBatchResponse). But strBody is empty and it doesn't read the "Body" field correctly. :

enter code here
     for (auto& v : jsonBatchResponse.get_child("responses"))
     {       
        std::string strID = v.second.get<std::string>("id", "");
        std::string strStatus = v.second.get<std::string>("status", "");
        std::string strBody = v.second.get<std::string>("body", "");
     }

It looks like v.second.getstd::string("body", "") is not the right way to read the JSON field. Is there any other way available (other than reading individual fields in the JSON value)? Please let me know.

The body is not a string.

So, getting the child object would be in order:

for (auto const& v : jsonBatchResponse.get_child("responses")) {
    std::string  strID     = v.second.get<std::string>("id", "");
    std::string  strStatus = v.second.get<std::string>("status", "");
    ptree const& body      = v.second.get_child("body");
}

If you add some output to that loop with e.g.

    std::cout << std::quoted(strID) << "\n";
    std::cout << std::quoted(strStatus) << "\n";
    write_json(std::cout, body);

It will print Live On Coliru

"1"
"200"
{
    "createdDateTime": "2021-04-22T09:24:59.394Z",
    "displayName": "Test1",
    "visibility": "public",
    "isMembershipLimitedToOwners": "false",
    "discoverySettings": {
        "showInTeamsSearchAndSuggestions": "true"
    },
    "memberSettings": {
        "allowCreateUpdateChannels": "true",
        "allowCreateUpdateRemoveConnectors": "true"
    },
    "guestSettings": {
        "allowCreateUpdateChannels": "true",
        "allowDeleteChannels": "false"
    },
    "messagingSettings": {
        "allowUserEditMessages": "true",
        "allowChannelMentions": "true"
    },
    "funSettings": {
        "allowGiphy": "true",
        "allowCustomMemes": "true"
    }
}

BONUS: Using a proper JSON library instead

Boost Property Tree is NOT a JSON library, and therefore has a lot of limitations.

Instead I suggest using Boost JSON:

Live On Coliru

#include <boost/json.hpp>
#include <boost/json/src.hpp>
#include <iostream>

namespace json = boost::json;

extern std::string sample;

int main() {
    json::object jsonBatchResponse = json::parse(sample).as_object();

    for (auto& v : jsonBatchResponse["responses"].as_array()) {
        auto& res = v.as_object();
        json::value id  = res["id"],     // string
            status      = res["status"], // integer
            body        = res["body"];   // object
        std::cout << id << "\n";
        std::cout << status << "\n";
        std::cout << body << "\n";
    }
}

std::string sample = R"(
{
    "responses": [{
        "id": "1",
        "status": 200,
        "headers": {
            "OData-Version": "4.0",
            "Content-Type": "application/json;odata.metadata=minimal;odata.streaming=true"
        },
        "body": {
            "createdDateTime": "2021-04-22T09:24:59.394Z",
            "displayName": "Test1",
            "visibility": "public",
            "isMembershipLimitedToOwners": false,
            "discoverySettings": {
                "showInTeamsSearchAndSuggestions": true
            },
            "memberSettings": {
                "allowCreateUpdateChannels": true,
                "allowCreateUpdateRemoveConnectors": true
            },
            "guestSettings": {
                "allowCreateUpdateChannels": true,
                "allowDeleteChannels": false
            },
            "messagingSettings": {
                "allowUserEditMessages": true,
                "allowChannelMentions": true
            },
            "funSettings": {
                "allowGiphy": true,
                "allowCustomMemes": true
            }
        }
    }]
}
)";

Prints

"1"
200
{"createdDateTime":"2021-04-22T09:24:59.394Z","displayName":"Test1","visibility":"public","isMembershipLimitedToOwners":false,"discoverySettings":{"showInTeamsSearchAndSuggestions":true},"memberSettings":{"allowCreateUpdateChannels":true,"allowCreateUpdateRemoveConnectors":true},"guestSettings":{"allowCreateUpdateChannels":true,"allowDeleteChannels":false},"messagingSettings":{"allowUserEditMessages":true,"allowChannelMentions":true},"funSettings":{"allowGiphy":true,"allowCustomMemes":true}}