C# conversion to DTO/JSON using Automapper

Question

I am trying to return a JSON in this format from the API using Automapper:

  {
    "Name": "Jason",
    "Subjects":
      [
        "Maths":{
                  "CourseName": "Maths",
                  "Score": 70
                },
      "English":{
                  "CourseName": "English",
                  "Score": 80
                }
      ]
  }

This is a special json where we can see that inside Subjects each subject's name is actually the CoursName property. Here is my model and DTO:

public class Student
{
    public string Name {get; set;}
    public ICollection Subjects {get; set;}
}

public class Subject
{
    public int Id {get; set;}
    public string CourseName {get; set;}
  public int Score {get; set;}
}

The problem is inside Subjects each subject has a Name coming from the CourseName which is inside the object.

Answer 1

The JSON you provided is not valid according to jsonformatter.curiousconcept.com.

This code works with a valid JSON output (RFC 8259).

using System.Collections.Generic;
using Newtonsoft.Json;

namespace JsonProgram
{
    public class Program
    {
        static void Main(string[] args)
        {
            var student = new Student
            {
                Name = "Jason",
                Subjects = new List<Subject>
                {
                    new Subject
                    {
                        Id = 1,
                        CourseName = "Maths",
                        Score = 70
                    },
                    new Subject
                    {
                        Id = 2,
                        CourseName = "English",
                        Score = 80
                    },
                }
            };
            var json = ToStudentJson(student);
        }

        private static string ToStudentJson(Student student)
        {
            var subjects = new List<Dictionary<string, SubjectBase>>();
            foreach (var subject in student.Subjects)
            {
                var dict = new Dictionary<string, SubjectBase>();
                dict.Add(subject.CourseName, new SubjectBase { CourseName = subject.CourseName, Score = subject.Score });
                subjects.Add(dict);
            }

            var studentJson = new StudentJson
            {
                Name = student.Name,
                Subjects = subjects.ToArray()
            };

            return JsonConvert.SerializeObject(studentJson);
        }
    }

    public class StudentJson
    {
        public string Name { get; set; }
        public Dictionary<string, SubjectBase>[] Subjects { get; set; }
    }
    public class Student
    {
        public string Name { get; set; }
        public ICollection<Subject> Subjects { get; set; }
    }

    public class Subject : SubjectBase
    {
        public int Id { get; set; }
    }

    public class SubjectBase
    {
        public string CourseName { get; set; }
        public int Score { get; set; }
    }
}

Output:

{
    "Name": "Jason",
    "Subjects": [
        {
            "Maths": {
                "CourseName": "Maths",
                "Score": 70
            }
        },
        {
            "English": {
                "CourseName": "English",
                "Score": 80
            }
        }
    ]
}