can't get data using entity framework

Question

I'm try to create web app using asp.net MVC4 I created TeacherController in my controller folder and model also finally i add Db-context also. I'm using sql server.

DbContext like this

using MvcTest2.Models;
using System;
using System.Collections.Generic;
using System.Data.Entity;
using System.Linq;
using System.Web;

namespace MvcTest5.Models.nuwan600
{
    public class nuwan600:DbContext
    {
        public DbSet<Qualifications> Qualifications { get; set; }
        public DbSet<School> School { get; set; }
        public DbSet<Teacher> Teacher { get; set; }
    }
}

Teacher model

using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
using System.ComponentModel.DataAnnotations.Schema;
using System.Linq;
using System.Web;

namespace MvcTest2.Models
{
    [Table("Teachers")]
    public class Teacher
    {
        [Key]
        public int TeacherID { get; set; }
        public String Name { get; set; }
        public int NIC { get; set; }
        public String Address { get; set; }
        public int Telephone { get; set; }

        public int SchoolID { get; set; }
        public int QualificationID { get; set; }
    }
}

and TeacherController

public ActionResult Index()
{
    int id = 1;
    nuwan600 Teachers = new nuwan600();
    Teacher teachermodle = Teachers.Teacher.Single(emp => emp.TeacherID==id);
    return View(teachermodle);
}

When I run this I got run time error (on this line: Teacher teachermodle = Teachers.Teacher.Single(emp => emp.TeacherID==id); )

One or more validation errors were detected during model generation:
MvcTest5.Models.nuwan600.Qualifications: EntityType 'Qualifications' has no key defined. Define the key for this EntityType.
Qualifications: EntityType: EntitySet 'Qualifications' is based on type 'Qualifications' that has no keys defined.
System.Data.Entity.ModelConfiguration.ModelValidationException

How can fix this ? error need a help.

Answer 1

The solution is to ... read the error message. ;-)

One or more validation errors were detected during model generation:

MvcTest5.Models.nuwan600.Qualifications: : EntityType 'Qualifications' has no key defined. Define the key for this EntityType. ...

In your Teacher class, you define that TeacherID is a key by using the [Key] attribute. Do the same for your Qualifications class: Mark the (primary) key using the [Key] attribute.