1. Develop without opening the designer or mapping in XML files.
2. Define model objects by simply writing POCO(Plain old CLR object) with no base classes required
3. Use a “convention over configuration” approach that enables database persistence without explicitly configuring anything

You can download the latest version of code first from this url : ADO.NET Entity Framework 4.1 – Update 1.

You can also install via NuGet.

install-package entityframework

Quick CRUD example with EF Code first.

First we will create the model classes.

public class Task
{
    public int TaskId { get; set; }
    public string TaskDescription { get; set; }
    public DateTime TaskDate { get; set; }
    public short TaskPriority { get; set; }
    public bool TaskIsDone { get; set; }
}

Now we need to create a Context for this. Context is required to use the POCO classes for DataAccess. It can be implemented by deriving it from DbContext class. The DbContext class is available under System.Data.Entity namespace.

public class TaskContext : DbContext
{
    public DbSet Tasks { get; set; }
}

We are done. Now we can use this class for communicating to Database.

Inserting records to Database.

using (TaskContext taskContext = new TaskContext())
{
    taskContext.Tasks.Add(new Task()
    {
        TaskDate = DateTime.Today,
        TaskDescription = "Create a blog post",
        TaskIsDone = false,
        TaskPriority = 1
    });
    if (taskContext.SaveChanges() != 0)
    {
        Console.WriteLine("Task added.");
    }
}

Updating records, updating the first task from Tasks, if the Task date is today.

using (TaskContext taskContext = new TaskContext())
{
    var currentTask = taskContext.Tasks.Where
		(task => task.TaskDate == DateTime.Today).FirstOrDefault();
	currentTask.TaskIsDone = true;
    if (taskContext.SaveChanges() != 0)
    {
        Console.WriteLine("Task updated.");
    }
}

Removing records, removing first task from Tasks, if the Task is completed.

using (TaskContext taskContext = new TaskContext())
{
    var completedTask = taskContext.Tasks.Where
        (task => task.TaskIsDone == true).FirstOrDefault();
    taskContext.Tasks.Attach(completedTask);
    taskContext.Tasks.Remove(completedTask);
    if (taskContext.SaveChanges() != 0)
    {
        Console.WriteLine("Task Deleted.");
    }
}

And retriving records, retriving all the tasks.

using (TaskContext taskContext = new TaskContext())
{
	var tasks = taskContext.Tasks.Where
		(task => task.TaskDate == DateTime.Today);
	tasks.ToList().ForEach(task =>
        Console.WriteLine("Task : {0} IsCompleted : {1}",
        task.TaskDescription, task.TaskIsDone));
}

It is very easy right? Another interesting question is where this data is getting stored? Because we didn’t specified any Database, or Connection string. By default the database will be created on local instance of SQLEXPRESS (localhost\SqlExpress). The database is named after the fully qualified name of your derived context, in our case that it will be “EFCodeFirst.TaskContext”. You can control this by providing connection string or by setting DefaultConnectionFactory.

You can provide connectionstring either in App.Config / Web.Config file or in code.

If you are providing the connection string in config, file the name of the connection string element should be same as Context class name. Like this

<connectionStrings>
  <add name="TaskContext"
  connectionString="Server=.\SqlExpress; Integrated Security=SSPI; Database=TaskDb;"
  providerName="System.Data.SqlClient"/>
</connectionStrings>

And if you want to use your own connection string name, you can do this using CreateConnection() method of the DefaultConnectionFactory class. You can also specify the connection string. You need to provide this information before creating the instance of task context.

Database.DefaultConnectionFactory.CreateConnection("TaskDbConnection");
using (TaskContext taskContext = new TaskContext())
{
	//Code.
}

Entity Framework also supports various databases also, like SQL CE, MySql etc. This can be achive either using the provider name is the config settings or by using DefaultConnectionFactory propery of Database class. Following statement helps to use SqlCe database instead of Sql Server

Database.DefaultConnectionFactory =
	new SqlCeConnectionFactory("System.Data.SqlServerCe.4.0");
using (TaskContext taskContext = new TaskContext())
{
	//Code.
}

Model validations also supported by entity framework. I may cover them in another post.

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EXEC sys.sp_configure N'remote access', N'1'
GO
RECONFIGURE WITH OVERRIDE
GO

It will enable remote connections to your SQL Server.
Happy Coding

This installer has encountered an unexpected error installing this package. This may indicate a problem with this package. The error code is 29506

Error Code 29506, While installing SQL Management Studio Express on Windows 7 x64

My initial thought was may be it is because of some problem with my downloaded installer. I downloaded it again and still the problem exists. Then I tried it with commandline(cmd), with Run As Administrator option and its worked

1. Add the Stored Procedure to the Entity Model Designer using Update Model From Database Option.


Add Procedure

2. If you are added successfully, you can get the procedure in Model Browser.


Model Browser

3. Right click on the Procedure name and select Create Function Import.


Create Function Import

4. It will popups a Windows with Stored Procedure Name, Function Import Name and Return Type. If the procedure returns nothing, you can choose none. If the procedure is returns single value, like UserId, Number Of Rows etc, then you can choose scalar option, where you need to specify the return type. And if the procedure is returns Table or Number of Rows, you need to choose the last option Entities, which will allow to select entities created in the Model as the Output. Sometimes we need to create a View in the DB and need to import it in the Model, so that we can use the View as the return type entity. Select the appropriate return type and click Ok. You can use this in code. In this code I am using a View to return the selected users.

Add Function Import dialog

using (SampleEntities context = new SampleEntities())
{
/*
* Thanks to Barry Soetoro.
* I was not calling the GetAllUsers function.
List<Users> Users = null;
Users = (from user in context.Users
             select user).ToList();
this.dataGridView1.DataSource = Users;
*/
//Updated Version.
IEnumerable<UsersView> userview = context.GetAllUsers();
this.dataGridView1.DataSource = userview;
}

This will display list of Users in the DataGridView. Happy Coding