ASP.Net MVC Entity Framework Entity Validation with DataAnnotation

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Validation of Entity with Entity Framework is a tricky way, but it is really simple. In this article we will try to understand how easily we can add the validation with any entity created by Entity Framework with database first approach by using partial classes and pure DataAnnotation. We will not use any if.. else... or switch... case statement to validate different property. It will work with client side validation as well as server side vatlidation because we are going to use the dataannotation only.

Let's create a MVC application in Visual Studio (I am using 2015)

  • File - New - Project
  • Web - ASP.Net Web Application
  • Give any name say "CustomerPortal"
  • Click OK
  • Select "MVC" and click OK

It will create the project with a complete structure, it will take a litle bit time and let it complete.

Run the application, it should work with Home, About and Contact page.

Let's create the database for our application say "CustomerDB"

  • Right click on App_Data Folder, Add - New Item
  • Data - SQL Server Database
  • Name it "CustomerDB.mdf"
  • Click OK

Our database is created in our App_Data folder, double click on the database and add table

  • Right Click on Table - Add New Table

Add following script to create the table

CREATE TABLE [dbo].[Customer]
    [FirstName] VARCHAR(20) NOT NULL, 
    [LastName] VARCHAR(20) NOT NULL, 
    [Address] VARCHAR(100) NOT NULL, 
    [Phone] VARCHAR(20) NOT NULL, 
    [Fax] VARCHAR(20) NULL, 
    [Email] VARCHAR(50) NULL, 
    [WebSite] VARCHAR(50) NULL

Click Update and then in opened model window click Update Database.

Now our database and table is ready to use, let's create the Endity Model in our Models folder:

  • Right click on Models Folder, Add - New Item
  • Data - ADO.Net Entity Data Model
  • Name it "CustomerModel"
  • Click Add
  • Select "EF Designer from database"
  • Click Next - Next
  • Select Table CheckBox and click Finish

Successfully we created our Entity Model, let's create a Customers controller in Controllers folder. Rebuild the application before creating the controller:

  • Choose "MVC 5 Controller with views, using Entity Frameworl"
  • Choose and enter value similar to the image
  • Click Add

Create Customer Controller

Run application and change Url to /customers. Complete feature Add, Edit, Detail and Delete all are working smoothly but not validating data.

Try to create a new customer and click create without providing any information, it will give error because validation is failed from database.

If we want, we can add the dataannotation code directly to the Customer entity and everything will work smooth. It is good until we change the database and update the Model from Database.

For permanent solution of above problem, we will create a new class inside the Models folder say "CustomerValidation.cs":

Mark this class as partial (it must be in the same namespace).

Copy all the properties from Customer.cs entity for which we want to add validation and paste them in our new class CustomerValidation and add dataannotation according to requirement.

After adding all the validation attributes, our CustomerValidation class will be:

public partial class CustomerValidation
    [Display(Name = "Firt Name")]
    [MaxLength(20, ErrorMessage = "Max 20 characters")]
    public string FirstName { get; set; }

    [Display(Name = "Last Name")]
    [MaxLength(20, ErrorMessage = "Max 20 characters")]
    public string LastName { get; set; }

    [Display(Name = "Customer Address")]
    [MaxLength(100, ErrorMessage = "Max 100 characters")]
    public string Address { get; set; }

    [Display(Name = "Customer Phone")]
    [MaxLength(12, ErrorMessage = "Max 12 characters")]
    public string Phone { get; set; }

    [MaxLength(12, ErrorMessage = "Max 12 characters")]
    public string Fax { get; set; }

    [MaxLength(50, ErrorMessage = "Max 50 characters")]
    public string Email { get; set; }

    [MaxLength(50, ErrorMessage = "Max 50 characters")]
    public string WebSite { get; set; }

Now we need to map this validation with our customer entity, for that add following lines after CustomerValidation class:

// Add this out of customerValidation class
// Note the partial keyword
public partial class Customer { }

Final output with validation by adding metadata & validation

Note: after adding validation through metadata, we have not touched the controller or view because we don't need to change anything in controller or view. This also dictate the design pattern, business logic change should not need any change in user interface or controller (representation).

In this way we can add validation to any Entity and use the entity directly in view.

Ali Adravi Having 13+ years of experience in Microsoft Technologies (C#, ASP.Net, MVC and SQL Server). Worked with Metaoption LLC, for more than 9 years and still with the same company. Always ready to learn new technologies and tricks.
  • mvc
  • validation
By Ali Adravi On 08 Jul, 18  Viewed: 2,801

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