MVC repository and interface returning Json - json

Question

I'm new at MVC and can't get this to work. I basically have a Users class, a UserRepository, and a IUser interface.
This is my code:
public class Users
{
public string UserName { get; set; }
public string Department { get; set; }
public string UserType { get; set; }
}
public class UsersRepository : TimeAttendanceMVC.Models.IUsers
{
public Users Return_UserName_Dept()
{
Users U = new Users();
List<Users> LoggedInUser = new List<Users>();
U.UserName = "TestUser";
U.Department = "Finance";
U.UserType = "Administrator";
LoggedInUser.Add(U);
//string json = JsonConvert.SerializeObject(LoggedInUser, Formatting.Indented);
//return json;
return Json(LoggedInUser.ToArray(), JsonRequestBehavior.AllowGet);
}
}
namespace TimeAttendanceMVC.Models
{
public class IUsers
{
List<Users> Return_UserName_Dept();
}
}
There are a few errors that I get. In UsersRepository.cs where i'm returning Json, the error says that "The name Json does not exist in the current context". The error from IUsers.cs is that "Return_UserName_Dept() must declare a body because it is not marked abstract...".
Can anybody please help me with this. I just don't know how this is supposed to work and i'm trying to learn MVC by working on this application. It's actually the FullCalendar application found here - link to FullCalendar. I'm trying to turn it into an MVC application.
EDIT:
Maybe I need to do this:
public JsonResult Return_UserName_Dept()
instead of public Users Return_UserName_Dept()

Answer 1

You should be doing this on your controller in some method which returns a json action (jsonresult). The repository should be returning your data only and all the operations you need to do, whether you're converting data to json or any other logic should happen at the controller or at some helper class which would be called by the controller..
Edit:
In order to have a method which returns a JsonResult, you need to have a reference to System.Web.Mvc.ActionResult and since the repository is usually at the model, you won't have this reference.. another thing is that you might be breaking your design the logic should be available at the controller for what you want
Edit 2:
The code below is from an old post you can see here. Note how the action PopulateDetails gets the user object from the repository and that's all the repository does.. the actual logic is happening inside this method, such as populate the rest of the UserModel class, and then it returns the JsonResult:
public JsonResult PopulateDetails(UserModel model)
{
UserResultModel userResultModel = new UserResultModel();
if (String.IsNullOrEmpty(model.UserId))
{
userResultModel.Message = "UserId can not be blank";
return Json(userResultModel);
}
User user = _userRepository.GetUser(model.UserId);
if (user == null)
{
userResultModel.Message = String.Format("No UserId found for {0}", model.UserId);
return Json(userResultModel);
}
userResultModel.LastName = user.LastName;
userResultModel.FirstName = user.FirstName;
userResultModel.Message = String.Empty; //success message is empty in this case
return Json(userResultModel);
}