Controller.Json() returns null

Question

I'm only using ASP.Net and MVC, no other libraries. The code is the following:

//ExpensesController.cs - the controller
public IActionResult getExpenses()
{
 List<ExpensesViewModel> list = new List<ExpensesViewModel>();
 string connectionString = "Data Source=DESKTOP-72RT825;Initial Catalog=AccountingDB;Integrated Security=True;Pooling=False";
 SqlConnection sqlConnection = new SqlConnection(connectionString);
 sqlConnection.Open();
 SqlCommand query = new SqlCommand("Select * from Expenses", sqlConnection);
 try
 {
 SqlDataReader reader;
 reader = query.ExecuteReader();
 while (reader.Read())
 {
 String name = reader.GetValue(0).ToString();
 String value = reader.GetValue(1).ToString();
 String date = reader.GetValue(2).ToString();
 list.Add(new ExpensesViewModel() { Name = name, Date=date, Value = value });
 Debug.Print(name + " " + " " + value);
 }
 }
 catch (SqlException ex)
 {
 Debug.Print(ex.Message);
 return Json(ex.Message);
 }
 JsonResult jsonResult = null;
 try
 {
 jsonResult = Json(list);
 }
 catch(Exception ex)
 {
 Debug.Write(ex.Message);
 }
 return jsonResult;
}
//The View Model
public class ExpensesViewModel
{
 public string Name;
 public string Value;
 public string Date;
}

The data that Json(list) returns is null, even though the list is not, I looked in the debugger, the connection to the DB is good, the data arrives, it is put into the list, but when I try and convert it to Json it fails. I've tried adding elements into the list manually, the Json function still returns null.

• Serge: What version of mvc are you using?

Answer 1

Change your view model to use properties, not fields:

public class ExpensesViewModel
{
 public string Name { get; set; }
 public string Value { get; set; }
 public string Date { get; set; }
}

The reason is that the default model binder binds to properties with public getters/setters.