Asp net mvc 4 ssn validation

Introduction

ASP.NET is a popular programming language used for building web applications. One common requirement in web applications is to validate user input, such as a Social Security Number (SSN). In this article, we will explore how to validate an SSN in an ASP.NET MVC 4 application.

SSN Validation Logic

Before we dive into the code, let's discuss the logic behind SSN validation. A valid SSN consists of nine digits, separated by hyphens in the format XXX-XX-XXXX. The first three digits represent the area number, the next two digits represent the group number, and the last four digits represent the serial number.

Implementing SSN Validation in ASP.NET MVC 4

To implement SSN validation in an ASP.NET MVC 4 application, we can use regular expressions. Regular expressions provide a powerful way to match patterns in strings. In this case, we can define a regular expression pattern that matches the format of a valid SSN.

using System.ComponentModel.DataAnnotations;

public class SsnValidationAttribute : ValidationAttribute
{
    private const string SsnPattern = @"^d{3}-d{2}-d{4}$";

    public override bool IsValid(object value)
    {
        if (value == null)
            return true;

        string ssn = value.ToString();

        return Regex.IsMatch(ssn, SsnPattern);
    }
}

In the code above, we define a custom validation attribute called SsnValidationAttribute. This attribute inherits from the ValidationAttribute class provided by ASP.NET MVC. We override the IsValid method to implement our SSN validation logic.

The regular expression pattern @"^d{3}-d{2}-d{4}$" matches the format of a valid SSN. The IsValid method checks if the provided value matches this pattern using the Regex.IsMatch method.

Using the SSN Validation Attribute

Now that we have implemented the SSN validation attribute, we can use it in our ASP.NET MVC 4 application. Let's say we have a model class called Person with an SSN property:

public class Person
{
    [SsnValidation(ErrorMessage = "Invalid SSN format")]
    public string Ssn { get; set; }
}

In the code above, we apply the SsnValidationAttribute to the Ssn property of the Person class. If the provided SSN does not match the expected format, the validation error message “Invalid SSN format” will be displayed.

Conclusion

In this article, we have explored how to validate an SSN in an ASP.NET MVC 4 application. We have implemented a custom validation attribute that uses a regular expression pattern to validate the SSN format. By applying this attribute to the SSN property of a model class, we can easily validate user input and display appropriate error messages.