In today’s post I am going to explain some of the important attributes in EFCodeFirst. Whey you do scaffolding with ASP.NET MVC this all attributes are where much important. So Let’s explore all the attributes.

Key Attribute:

When you put this attribute in the class it tell that this property is part of the primary key and If you use code first when its create table based on this entity then it will be a part of primary key of table. Here is the sample example of that.

[Key]

public int ArticleId { get; set; }

Here article ID will act as primary key.

Foreign Key Attribute:

This attribute is very useful when you deal with interrelated tables You can specify the column in entity which is foreign key for that Like following.

[ForeignKey("CategoryId")]

public ICollection<Category> Categories { get; set; }

In above example CategoryId is a foreign key of category table to article table.

ScaffoldColumn Attribute:

When you Scaffold your application with ASP.NET MVC scaffold feature or dynamic data with asp.net webforms this attribute will tell that this column need to have field for that. You can write that column like following.

[ScaffoldColumn(false)]

public int ArticleId { get; set; }

Here it will tell article id will not have UI in scaffoling.

StringLength Attribute:

This attribute is used to specify the maximum length of a string. This attribute is very usefull in validation and other stuff. This attribute only applied to the Stringlength property like following.

[StringLength(512)]

public string Title { get; set; }

Here in the above code it tell that title could not have more then 512 character string.

There lots of other attributes also. I will blog about it in future posts. Hope you liked this. Stay tuned for more..Happy Programming.

In the previous post I have already explained How we can list data from database easily with the help of EFCodeFirst . In this post I am going to explain How we can complete Create,Edit,Delete and Details operations within 10 minutes. So let’s first Start with Create a new Customer.I am going use same example of customer from previous post. So we have customer controller there so Let’s first create a new view for Create via Selecting View in Create() method of Customer Controller and Clicking on Add View and dialog box will open for add view like following.



As you can see in the above template I have selected Customer Model Class for strongly typed view and Selected Scaffold template as Create once you click Add your view will be ready. Now its time to write for code in customer controller to Add Customer. So I have modified Create Method of customer controller which we have created like following.

[HttpPost]
public ActionResult Create(Models.Customer customer)
{
  try
  {
      using (var databaseContext = new Models.MyDataContext())
      {
          databaseContext.Customer.Add(customer);
          databaseContext.SaveChanges();
      }
    
      return RedirectToAction("Index");
  }
  catch
  {
      return View();
  }
}

That's it. We have done with Create Customer now. In the above databasecontext add method will add customer and SaveChanges method will save changed to database.
Now once we are done with Add its time to create edit and update functionality. Let’s first Add a view via Selecting view with Edit Method in clicking on Add view. Once you click a dialogbox for add View will open for that like following.



As you can see you I have selected scaffold template as Edit and I have Created Strongly typed view with Customer class. Once you click add it will create a new view for Edit. Now our Edit View is ready so let’s write code for Edit/Update in database. So first we have to modify Edit(int Id) method like following which will return specific customer with View. Following is a code for that.

public ActionResult Edit(int id)
{
  using (var databaseContext = new Models.MyDataContext())
  {
      return View(databaseContext.Customer.Find(id));
  }
}

Now let write code to update the changes to database. So for that I have modified another ActionResult Edit of customer controller like following.

[HttpPost]
public ActionResult Edit(int id, Models.Customer customer)
{
  try
  {
      using (var databaseContext = new Models.MyDataContext())
      {
          databaseContext.Entry(customer).State= System.Data.EntityState.Modified;
          databaseContext.SaveChanges();
      }
      return RedirectToAction("Index");
  }
  catch
  {
      return View();
  }
}

That's it we are done with the edit stuff.In above code the state modified will tell databasecontext that customer details is modified and savechanges will save changed to database. Now its time to create view for delete functionality. So I have clicked on Add View and Created a view for delete like following.



Here I have create Strongly typed view with Delete Scaffold Template. Now let’s modified both Delete Action Result in Customer Controller class. First Action result will return customer which we are going to delete and another delete action result with id will delete the customer from database and then it will return to main customer page. I have modified the code for both as following.

// GET: /Customer/Delete/5

public ActionResult Delete(int id)
{
  using (var databaseContext = new Models.MyDataContext())
  {
      return View(databaseContext.Customer.Find(id));
  }

}

//
// POST: /Customer/Delete/5

[HttpPost]
public ActionResult Delete(int id,Models.Customer customer)
{
  try
  {
      using (var databaseContext = new Models.MyDataContext())
      {
          databaseContext.Entry(databaseContext.Customer.Find(id)).State = System.Data.EntityState.Deleted;
          databaseContext.SaveChanges();
      }

      return RedirectToAction("Index");
  }
  catch
  {
      return View();
  }
}

Here I have done something different then editing stuff to demonstrate the feature of Entity framework. You can also use Id for finding the current customer and then change its state to delete and SaveChanges will save that to in database. So now we are done with delete also. It’s now time to create details part. So same as above I have create a view with scaffold template details with customer model like following.



Once we are done with creating view . It’s time to change the code for Details Action Result like following to return current customer detail.

public ActionResult Details(int id)
{
  using (var databaseContext = new Models.MyDataContext())
  {
      return View(databaseContext.Customer.Find(id));
  }
}

So that's it. We are done with all the stuff. So with Entity Framework code first. You can create basic CRUD application within 30 minutes without writing so much code. Hope you liked it. Stay tuned for more.. Till that Happy programming.

I have been playing with EFCodeFirst now and I found it very interesting with that you could write your application fast and easily. So I have decided to write series of blog posts for CRUD Operations using ASP.NET MVC 3 and EFCodeFirstCTP5.0 . You can very easily create CRUD within some minutes of code. So let’s start first thing is to create an ASP.NET MVC 3 application like following.



Once you click OK. It will ask for the which type of View your are going to use. I have used Razor and HTML5 Semantic like following.



Now once we have create a application Now its time to add EFCodeFirst reference via NuGet. So Go to the Library Package Manager –> Manage Nuget Package Manager. It will open up a dialog like following. Search EFCodeFirst and then it will fine EFCodeFirst package like following.



Once you click Install it will add reference to your ASP.NET MVC Application like following.



So now all the things are set Its time to code now. So first I have Create my Table which is very simple table called Customer like I have used in previous post. For your reference I am putting the create table script below.

SET ANSI_NULLS ON
GO

SET QUOTED_IDENTIFIER ON
GO

CREATE TABLE [dbo].[Customer](
   [CustomerId] [int] IDENTITY(1,1) NOT NULL,
   [FirstName] [nvarchar](50) NULL,
   [LastName] [nvarchar](50) NULL,
   [Address] [nvarchar](256) NULL,
   [City] [nvarchar](50) NULL,
CONSTRAINT [PK_Customer] PRIMARY KEY CLUSTERED
(
   [CustomerId] ASC
)WITH (PAD_INDEX  = OFF, STATISTICS_NORECOMPUTE  = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS  = ON, ALLOW_PAGE_LOCKS  = ON) ON [PRIMARY]
) ON [PRIMARY

Now let's create our entity class called customer like following.

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

namespace CodeSimplified.Models
{
   public class Customer
   {
       public int CustomerId { get; set; }
       public string FirstName { get; set; }
       public string LastName { get; set; }
       public string Address { get; set; }
       public string City { get; set; }
   }
}

Now Its time to create a our datacontext class So I have created MyDataContext class inherited from the DBContextClass . In that I have defined my customer dbset and Also I override the default plural behaviour in ModelCreating Table. DBSet will tell datacontext which table we need to refer. So following is code for that.

using System;
using System.Collections.Generic;
using System.Data.Entity;
using System.Linq;
using System.Web;
using System.Data.Entity.ModelConfiguration.Conventions.Edm.Db;

namespace CodeSimplified.Models
{
   public class MyDataContext:DbContext
   {
       public DbSet<Customer> Customer { get; set; }

       protected override void OnModelCreating(System.Data.Entity.ModelConfiguration.ModelBuilder modelBuilder)
       {
           modelBuilder.Conventions.Remove<PluralizingTableNameConvention>();
       }
   }
}

Now our database access stuff is ready now It’s time to create controller. So I have clicked controller folder and click on add new controller so add controller dialog box will appear like following.



It will create a controller class like following.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Mvc;

namespace CodeSimplified.Controllers
{
   public class CustomerController : Controller
   {
       //
       // GET: /Customer/

       public ActionResult Index()
       {
           return View();
       }

       //
       // GET: /Customer/Details/5

       public ActionResult Details(int id)
       {
           return View();
       }

       //
       // GET: /Customer/Create

       public ActionResult Create()
       {
           return View();
       }

       //
       // POST: /Customer/Create

       [HttpPost]
       public ActionResult Create(FormCollection collection)
       {
           try
           {
               // TODO: Add insert logic here

               return RedirectToAction("Index");
           }
           catch
           {
               return View();
           }
       }
      
       //
       // GET: /Customer/Edit/5

       public ActionResult Edit(int id)
       {
           return View();
       }

       //
       // POST: /Customer/Edit/5

       [HttpPost]
       public ActionResult Edit(int id, FormCollection collection)
       {
           try
           {
               // TODO: Add update logic here

               return RedirectToAction("Index");
           }
           catch
           {
               return View();
           }
       }

       //
       // GET: /Customer/Delete/5

       public ActionResult Delete(int id)
       {
           return View();
       }

       //
       // POST: /Customer/Delete/5

       [HttpPost]
       public ActionResult Delete(int id, FormCollection collection)
       {
           try
           {
               // TODO: Add delete logic here

               return RedirectToAction("Index");
           }
           catch
           {
               return View();
           }
       }
   }
}

Now once our controller is ready now its time to write some code for Index Action Result which we are going to have a list of customer. So I have changed Index Action Result like following to return customer view.

public ActionResult Index()
{
   using (var databaseContext=new Models.MyDataContext())
   {
       return View(databaseContext.Customer.ToList());
   }
}

Now let create a view from the controller. So Selected a view in right click Add View from Index Action Result. Here I have selected strongly typed view with Customer Model and selected list Template like following.



That’s it we are done with listing of the customer. Now its time to run our application and following is the output as expected.



Hoped you like this…Stay tuned for more.. Till that happy programming.

Recently I was working on one sample application with EFCodeFirst with the existing database.After doing all the coding I have found a error “Invalid object name 'dbo.Customers'.”. Following was my code for data context.

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

namespace CodeSimplified.Models
{
  public class MyDataContext:DbContext
  {
      public DbSet<Customer> Customer { get; set; }

      protected override void OnModelCreating(System.Data.Entity.ModelConfiguration.ModelBuilder modelBuilder)
      {
     
      }
  }
}

And following is code for my entity model class.

public class Customer
{
  public int CustomerId { get; set; }
  public string FirstName { get; set; }
  public string LastName { get; set; }
  public string Address { get; set; }
  public string City { get; set; }
}

Once I run the application I was getting following error.



As you can see from my code that it should be dbo.customer name. So after digging into the issue I have found that I need to remove the plural table name. Here is a forum that is saying the same.

http://social.msdn.microsoft.com/Forums/en-ie/adonetefx/thread/719f3e4d-073b-49fe-9968-945acde27bb7.

Now there are two ways of resolving this issue.
1) Either explicitly map entity class with table attribute like I have changed my code like following.

[Table("Customer",SchemaName="dbo")]
public class Customer
{
  public int CustomerId { get; set; }
  public string FirstName { get; set; }
  public string LastName { get; set; }
  public string Address { get; set; }
  public string City { get; set; }
}

Another one is you need to remove default plural table name via overriding the onModelCreating event like following.

using System;
using System.Collections.Generic;
using System.Data.Entity;
using System.Linq;
using System.Web;
using System.Data.Entity.ModelConfiguration.Conventions.Edm.Db;

namespace CodeSimplified.Models
{
  public class MyDataContext:DbContext
  {
      public DbSet<Customer> Customer { get; set; }

      protected override void OnModelCreating(System.Data.Entity.ModelConfiguration.ModelBuilder modelBuilder)
      {
          modelBuilder.Conventions.Remove<PluralizingTableNameConvention>();
      }
  }
}

That’s it now error is gone. My code is work perfectly!!. Hope this will help you.Stay tuned for more..Till that happy programming.