Agfdhyk

Controller:

using System;

using System.Collections.Generic;

using System.Linq;

using System.Web;

using System.Web.Mvc;

using MvcApplication1.Models;

using System.ComponentModel.DataAnnotations.Schema;



namespace MvcApplication1.Controllers

{

    public class studentsController : Controller

    {

        //

        // GET: /students/



        public ActionResult details()

        {

            int id = 16;

            studentContext std = new studentContext();

           student first = std.details.Single(m => m.RollNo == id);

            return View(first);

        }



    }

}

DbContext Model:

using System;

using System.Collections.Generic;

using System.Linq;

using System.Web;

using System.Data.Entity;



namespace MvcApplication1.Models

{

    public class studentContext : DbContext

    {

        public DbSet<student> details { get; set; }

    }

}

Model:

using System;

using System.Collections.Generic;

using System.Linq;

using System.Web;

using System.ComponentModel.DataAnnotations.Schema;



namespace MvcApplication1.Models

{

    [Table("studentdetails")]

    public class student

    {

        public int RollNo;

        public string Name;

        public string Stream;

        public string Div;

    }

}

Database table:

CREATE TABLE [dbo].[studentdetails](

    [RollNo] [int] NULL,

    [Name] [nvarchar](50) NULL,

    [Stream] [nvarchar](50) NULL,

    [Div] [nvarchar](50) NULL

)  

In global.asax.cs

Database.SetInitializer<MvcApplication1.Models.studentContext>(null);

The above code lists all the classes I am working on. Upon running my application am receiving the error:

"One or more validation errors were detected during model generation" along with "Entity type has no key defined".

The Model class should be changed to :

using System.Collections.Generic;

using System.Linq;

using System.Web;

using System.ComponentModel.DataAnnotations.Schema;

using System.ComponentModel.DataAnnotations;



namespace MvcApplication1.Models

{

    [Table("studentdetails")]

    public class student

    {

        [Key]

        public int RollNo { get; set; }



        public string Name { get; set; }



        public string Stream { get; set; }



        public string Div { get; set; }

    }

}

1. Make sure public members of student class are defined as properties w/ {get; set;} (yours are public variables - a common mistake).




2. Place a [Key] annotation on top of your chosen property.

There are several reasons this can happen. Some of these I found here, others I discovered on my own.

• If the property is named something other than Id, you need to add the [Key] attribute to it.


• The key needs to be a property, not a field.


• The key needs to be public
  


• The key needs to be a CLS-compliant type, meaning unsigned types like uint, ulong etc. are not allowed.


• This error can also be caused by configuration mistakes.

i know that this post is late but
this solution helped me:

    [Key]

    [Column(Order = 0)]

    public int RoleId { get; set; }

added [Column(Order = 0)]
after [Key]
can be added by increment by 1:

    [Key]

    [Column(Order = 1)]

    public int RoleIdName { get; set; }

etc...

In my case, I was getting the error when creating an "MVC 5 Controller with view, using Entity Framework".

I just needed to Build the project after creating the Model class and didn't need to use the [Key] annotation.