Custom Validations in ASP.NET MVC(Server Side)

There are many types of validations that do allow in MVC Models such like Required Field Validator, Data Type Validator, Range Validator and etc… But there is a way that the developer can write his own Validation Rules and work with them as a normal validator that comes built-in. This is way far easier in MVC.

First Create a New MVC 3 Application. Create a new class in the Model or can use the existing one as well. Add a reference toSystem.ComponentModel.DataAnnotations.

1	using System.ComponentModel.DataAnnotations;

In this case, I am going to use as sample model named User for the validation.

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public class User     {         public int UserID;         public string Gender;         public string Salution;         public string UserName;         public string FirstName;         public string LastName;         public DateTime RegistrationTime;     }

I do need to validate the inputs{“Male” or “Female”} for Gender of the User and I would like to name that controller as GenderValidation.

Here comes the action.

Define a class named GenderValidationAttribute that inherits from ValidationAttribute. Then override the method IsValid from the Base class.

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public class GenderValidationAttribute : ValidationAttribute     {           protected override ValidationResult  IsValid(object value,  ValidationContext validationContext)         {             string gender = value.ToString();             if (!(value.Equals("Male") | value.Equals("Female")))             {                 return new ValidationResult("Invalid Input for Gender.");             }             return ValidationResult.Success;         }     }

Now this can be used as normal as a general Validation Attribute. Change the User Model like below.

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public class User     {         public int UserID;         [GenderValidation]         public string Gender;         public string Salution;         public string UserName;         public string FirstName;         public string LastName;         public DateTime RegistrationTime;     }