How return custom anonymous type?

Question

How do I return an anonymous type which depends on the fields parameter in which properties which have to be included in anonymous type are listed? Task entity has more than 20 properties, and customers want to receive different combinations of properties.

public class Test
{
    public class Task
    {
        public int Id { get; set; }
        public string Name { get; set; }
        public string Description { get; set; }
        //... more 20 properties
    }

    public List<Task> Tasks = new List<Task>();

    public Test()
    {
        Tasks.Add(new Task { Id = 1, Name = "Task #1", Description = "Description task #1" });
        Tasks.Add(new Task { Id = 2, Name = "Task #2", Description = "Description task #2" });
        Tasks.Add(new Task { Id = 3, Name = "Task #3", Description = "Description task #3" });
    }

    public IEnumerable<object> GetAllTasks(string fields)
    {
        //if fields == 'Id,Name' then return anonymous type new { Id = t.Id, Name = t.Name }
        return Tasks.Select(t => new { Id = t.Id, Name = t.Name });

        //if fields == 'Id,Name,Description' then return anonymous type new { Id = t.Id, name = t.Name, Description = t.Description }
        return Tasks.Select(t => new { Id = t.Id, Name = t.Name, Description = t.Description });
    }
}

Answer 1

I hope it will help you

public List<Task> Tasks = new List<Task>();

public void Test()
{
    Tasks.Add(new Task { Id = 1, Name = "Task #1", Description = "Description task #1" });
    Tasks.Add(new Task { Id = 2, Name = "Task #2", Description = "Description task #2" });
    Tasks.Add(new Task { Id = 3, Name = "Task #3", Description = "Description task #3" });
}

public ActionResult Index()
{
    Test();

    return Json(GetAllTasks(), JsonRequestBehavior.AllowGet);
}

public IEnumerable<object> GetAllTasks()
{
    return Tasks.Select(GetTask);
}

private object GetTask(Task task)
{
    dynamic expandoObject = new ExpandoObject();
    //your if statment block
    if (task.Id == 1)
    {
        expandoObject.Id = task.Id;
    }

    expandoObject.Name = task.Name;
    expandoObject.Description = task.Description;

    var dictionary = expandoObject as IDictionary<string, object>;
    return dictionary.ToDictionary(item => item.Key, item => item.Value);
}

the view result:

[
   [
      {
         "Key":"Id",
         "Value":1
      },
      {
         "Key":"Name",
         "Value":"Task #1"
      },
      {
         "Key":"Description",
         "Value":"Description task #1"
      }
   ],
   [
      {
         "Key":"Name",
         "Value":"Task #2"
      },
      {
         "Key":"Description",
         "Value":"Description task #2"
      }
   ],
   [
      {
         "Key":"Name",
         "Value":"Task #3"
      },
      {
         "Key":"Description",
         "Value":"Description task #3"
      }
   ]
]