Introducing Code First Entity Framework 4.0!

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

namespace IdeaMVC.Models
{
    public class IdeaContext:DbContext
    {
        public DbSet<IdeaModel> Ideas {get; set;}
    }
}

<configuration>
  <connectionStrings>
    <add
      name="IdeaContext"
      providerName="System.Data.SqlClient"
      connectionString="Server=.\SQLEXPRESS;Database=Products;Trusted_Connection=true;"/>
  </connectionStrings>

The current connection string will create a database called Products  in the local SQL Server if it doesn’t already exist. Your connection string could very well have pointed to an attached DB or SQL CE

A few important points here

1. The name of the connection string should be the name of the Datacontext (which in our case is IdeaContext and hence the connection string is also called IdeaContext)
2. If you want to specifically rename the connection string you can do that by passing the new connection string name to the base DataContext constructor . For Example

   public IdeaContext():base("MyConnectionString"){}

3. If the database is not present at the specified location it will be specifically created based on the DataModel
4. If the database is already present its schema is matched to the existing datamodel schema to check for updates.

Creating the database from the datamodel follows some rules . For example, it tries to identity the PK as the name of the datamodel+ID so in this case it recognizes the IdeaModelID as the PK. If your PK is defined differently you can specify a [Key] attribute  from the .NET 4.0 System.Component.DataAnnotations namespace to indicate the PK.

Many configurations are possible but for now lets take the most basic case and continue.

OK so we defined the model, the datacontext and the connection string…Next we need to use the datacontext…

Since i am using the MVC model, i will access my list in the Index method  (Note that this can be used in any .NET app)

So my Index method looks like this

 IdeaContext context= new IdeaContext();
 var j = context.Ideas;
 return View(j.ToList());

  [HttpPost]
        public ActionResult Create(IdeaModel  idea)
        {
            try
            {
                if (ModelState.IsValid)
                {
                    idea.IdeaID = new Random().Next();
                    IdeaContext context = new IdeaContext();
                    context.Ideas.Add(idea);
                    context.SaveChanges();
                    return View("Details", idea);
                }
                else
                {
                    return View("Create", idea);
                }
            }
            catch (Exception ex)
            {
                return View();
            }
        }

DbDatabase.SetInitializer(new DropCreateDatabaseIfModelChanges<IdeaContext>());