Question

I am new to MS’s MVC4, and I have been given a database for which I must build a CRUD front-end. The tables all have composite primary keys of the form [TableID, TableName, EffectiveDate]. I cannot alter the database design. I used the Database-first technique and the EF 5.x DbContext generator for C# tool to create the models, but the generated model files do not contain annotations for the composite keys. Here is an example of the Department table, with primary key = [DeptID, DeptName, EffDate].

//------------------------------------------------------------------------------
// <auto-generated>
//    This code was generated from a template.
//
//    Manual changes to this file may cause unexpected behavior in your application.
//    Manual changes to this file will be overwritten if the code is regenerated.
// </auto-generated>
//------------------------------------------------------------------------------

namespace BillableUnits4.Models
{
    using System;
    using System.Collections.Generic;

    public partial class Department
    {
        public int DeptID { get; set; }
        public string DeptName { get; set; }
        public System.DateTime EffDate { get; set; }
        public string Status { get; set; }
        public string Fund { get; set; }
        public string DeptNo { get; set; }
        public string RevenueAccount { get; set; }
        public string BalanceSheetAccount { get; set; }
    }
}

I’m betting the keys should look like this:

    [key] 
    public int DeptID { get; set; }
    [key]
    public string DeptName { get; set; }
    [key]
    public System.DateTime EffDate { get; set; }

Do I even need to annotate the primary key components? If so, should I add the annotations to the generated model files? (regenerating the files would erase any changes I make by hand, obviously). Is there a way to tell MVC4 / Visual Studio to generate the files with the proper annotations?

Answer 1

You don’t have to annotate something that is obvious for the database 🙂 Your code will not use database specific annotations, so I wound’t worry about that.

You might want to decorate your model with a [Required] or other annotations that make sense for your app’s data consistency. In such case you might either go with Partial Classes (http://weblogs.asp.net/scottgu/archive/2010/01/15/asp-net-mvc-2-model-validation.aspx) or by implementing ViewModels (that you could modify without worrying about the auto-generated classes that you shouldn’t really modify)