In this article I will explain with an example, how to use the RegularExpression Data Annotation in ASP.Net MVC Razor.
The RegularExpression Data Annotation can be applied to Model Properties and used for enforcing Regular Expression (Regex) validations in ASP.Net MVC Razor.
Configuring Bundles and enabling Client Side Validation
Please refer the following article for complete information on how to configure Bundles and enable Client Side validation in ASP.Net MVC project.
Note: By default the validation done using Data Annotation attributes is Server Side. And hence to make it work Client Side, the Client Side validation must be enabled.
Model
The following Model class consists of one property UserName to which the following validation Data Annotation attributes have been applied.
1. Required Data Annotation attribute.
2. RegularExpression Data Annotation attribute.
The RegularExpression Data Annotation attribute accepts the Regular Expression as first parameter. The Regular expression will allow only Upper Case and Lower Case Alphabets and Numbers (Digits).
The Required Data Annotation and the RegularExpression Data Annotation attributes have been specified with a property Error Message with a string value. As the name suggests, this string value will be displayed to the user when the respective validation fails.
public class PersonModel
{
[Display(Name = "Username")]
[Required(ErrorMessage = "Username is required.")]
[RegularExpression("^[a-zA-Z0-9]*$", ErrorMessage = "Only Alphabets and Numbers allowed.")]
public string UserName { get; set; }
}
Controller
The Controller consists of two Action methods.
Action method for handling GET operation
Inside this Action method, simply the View is returned.
Action method for handling POST operation
This action method handles the POST operation and when the form is submitted, the object of the PersonModel class is sent to this method.
public class HomeController : Controller
{
// GET: Home
public ActionResult Index()
{
return View();
}
[HttpPost]
public ActionResult Index(PersonModel person)
{
return View();
}
}
View
Inside the View, in the very first line the PersonModel class is declared as Model for the View.
The View consists of an HTML Form which has been created using the Html.BeginForm method with the following parameters.
ActionName – Name of the Action. In this case the name is Index.
ControllerName – Name of the Controller. In this case the name is Home.
FormMethod – It specifies the Form Method i.e. GET or POST. In this case it will be set to POST.
Inside the View, the following three HTML Helper functions are used:-
1. Html.LabelFor – Displaying the Model property name.
2. Html.TextBoxFor – Creating a TextBox for the Model property.
3. Html.ValidationMessageFor – Displaying the Validation message for the property.
There is also Submit button which when clicked, the Form gets submitted.
The jQuery and the jQuery Validation script bundles are rendered at the end of the Model using the Scripts.Render function.
@model Alphanumeric_Validation_MVC.Models.PersonModel
@{
Layout = null;
}
<!DOCTYPE html>
<html>
<head>
<meta name="viewport" content="width=device-width"/>
<title>Index</title>
<style type="text/css">
body {
font-family: Arial;
font-size: 10pt;
}
.error {
color: red;
}
</style>
</head>
<body>
@using (Html.BeginForm("Index", "Home", FormMethod.Post))
{
<table>
<tr>
<td>@Html.LabelFor(m => m.UserName)</td>
<td>@Html.TextBoxFor(m => m.UserName)</td>
<td>@Html.ValidationMessageFor(m => m.UserName, "", new { @class = "error" })</td>
</tr>
<tr>
<td></td>
<td><input type="submit" value="Submit"/></td>
<td></td>
</tr>
</table>
}
</body>
@Scripts.Render("~/bundles/jquery")
@Scripts.Render("~/bundles/jqueryval")
</html>
Screenshot
![RegularExpression Data Annotation example: Perform validations using RegularExpression Data Annotation in ASP.Net MVC]()
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