Data Annotation is used to add validation rules to our application by using simple attributes. Data Annotation contains different types of validation attributes to enforce the validation rules. To work with the data annotation, below namespace must be added.

Association is used to specify an entity member that represents the data relationship like Foreign key relationship.

ConcurrencyCheck is used to specify whether a property will participate in optimistic concurrency check or not.

CreditCard is used to check whether the field is credit card number or not.

CustomValidation is used to specify the user created method i.e used to implement custom validation to a property or class.

DataType is used to specify the additional datatype name i.e required to be associated with the data field.

Example Application on Data Annotations Follow the below steps to work with the Data Annotations.

• Open a new MVC Application.
• Create a Model as shown in the below figures

• Then a new window will appear as shown in the below figure. Give the name as Employee.

• Write the following code under the Employee class in the model.

[csharp] public class Employee { [Key] public int EmpId { get; set; } [Required(ErrorMessage="Please enter the EmpName")] public string EmpName { get; set; } [Required(ErrorMessage = "Please enter the EmpSalary")] public int EmpSalary { get; set; } [Required(ErrorMessage = "Please enter the EmpAddress")] public string EmpAddress { get; set; } [Required(ErrorMessage = "Please enter the EmpEmailId")] [EmailAddress(ErrorMessage="Please enter the valid email id")] public string EmpEmailId { get; set; } [Required(ErrorMessage = "Please enter the EmpPhone")] public string EmpPhone { get; set; } } [/csharp] Now add a view and write the following code. [html] @{ ViewBag.Title = "Employee"; } <h2>Employee</h2> @using (Html.BeginForm("Submit")) { <table> <tr> <td>@Html.Label("L1", "EmpId")</td> <td>@Html.TextBox("T1")</td> </tr> <tr> <td>@Html.Label("L2", "EmpName")</td> <td>@Html.TextBox("T2")</td> </tr> <tr> <td>@Html.Label("L3", "EmpSalary")</td> <td>@Html.TextBox("T3")</td> </tr> <tr> <td>@Html.Label("L4", "EmpAddress")</td> <td>@Html.TextBox("T4")</td> </tr> <tr> <td>@Html.Label("L5", "EmpEmail")</td> <td>@Html.TextBox("T5")</td> </tr> <tr> <td>@Html.Label("L6", "EmpPhone")</td> <td>@Html.TextBox("T6")</td> </tr> </table> <input type="submit" value="submit" /> } [/html] Now add a controller and give the name as Employee and write the following code. [csharp] public ActionResult Employee() { return View(); } [/csharp] Run the application. The following window will appear. Click on submit button. Then you will get error messages.