In this article I will explain with an example, how to perform AlphaNumeric TextBox Validation i.e. allow only Alphabet and Number characters validation on Client Side using Data Annotation and jQuery in ASP.Net Core MVC.
The AlphaNumeric TextBox Validation i.e. allow only Upper Case and Lower Case Alphabet and Number (Digits) characters validation will be performed on Client Side using Model class and Data Annotation attributes in ASP.Net Core MVC.
Note: For beginners in ASP.Net Core (.Net Core 7), please refer my article ASP.Net Core 7: Hello World Tutorial with Sample Program example.
 
 

Model

The following Model class consists of one property UserName. The property is decorated with the following Data Annotation attributes for performing validations.
1. Required Data Annotation attribute.
2. RegularExpression Data Annotation attribute.
Note: The Data Annotations attributes can be used with the Entity Data Model (EDM), LINQ to SQL, and other data models.
 
The RegularExpression Data Annotation attribute accepts the Regular Expression as first parameter.
The Regular Expression will allow only Upper Case, Lower Case Alphabets and Numbers (Digits).
The Required Data Annotation and the RegularExpression Data Annotation attributes have been specified with a property ErrorMessage with a string value. As the name suggests, this string value will be displayed to the user when the respective validation fails.
Valid example: Mudassar25
using System.ComponentModel.DataAnnotations;
 
namespace Alphanumeric_Validation_MVC_Core.Models
{
    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 following 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 state of the submitted Model is checked using ModelState.IsValid property.
Note: ModelState.IsValid property is an inbuilt property which verifies two things:
          1. Whether the Form values are bound to the Model.
          2. All the validations specified inside Model class using Data annotations have been passed.
 
Finally, the View is returned to the Index View.
public class HomeController : Controller
{
    public IActionResult Index()
    {
        return View();
    }
 
    [HttpPost]
    public IActionResult Validate()
    {
        if (ModelState.IsValid)
        {
            // Validation Success.
        }
 
        return View("Index");
    }
}
 
 

View

HTML Markup

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 following ASP.Net Tag Helpers attributes.
asp-action – Name of the Action. In this case the name is Validate.
asp-controller – Name of the Controller. In this case the name is Home.
method – It specifies the Form Method i.e. GET or POST. In this case it will be set to POST.
 
The Form consists of a Label, an HTML INPUT TextBox, a SPAN element and a Submit Button.
The TextBox has been set with the following Tag Helpers attributes:
asp-for – The Model property to which validation will be performed. In this case UserName.
asp-validation-for – For displaying the validation message for the Model property.
 

Submitting the Form

When the Submit Button is clicked, the Form gets submitted and the UserName value is sent to the Controller.
 

Enabling Client-Side validations

By default, the validations using Data Annotations and Model class is performed on Server Side.
In order to enable Client-Side validations, you will need to inherit the following script files.
1. jquery.min.js
2. jquery.validate.js
3. jquery.validate.unobtrusive.js
Once, the above files are inherited automatically, the Client-Side validations using Data Annotations is enabled.
@model Alphanumeric_Validation_MVC_Core.Models.PersonModel
@addTagHelper*, Microsoft.AspNetCore.Mvc.TagHelpers
@{
    Layout = null;
}
 
<!DOCTYPE html>
 
<html>
<head>
    <meta name="viewport" content="width=device-width" />
    <title>Index</title>
</head>
<body>
    <form method="post" asp-controller="Home" asp-action="Validate">
        <table>
            <tr>
                <td><label asp-for="UserName"></label></td>
                <td><input type="text" asp-for="UserName" /></td>
                <td><span asp-validation-for="UserName" class="error"></span></td>
            </tr>
            <tr>
                <td></td>
                <td><input type="submit" value="Submit" /></td>
                <td></td>
            </tr>
        </table>
    </form>
 
    <script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.7.1/jquery.min.js"></script>
    <script type="text/javascript"src="https://cdnjs.cloudflare.com/ajax/libs/jquery-validate/1.19.3/jquery.validate.js"></script>
    <script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/jquery-validation-unobtrusive/3.2.12/jquery.validate.unobtrusive.js"></script>
</body>
</html>
 
 

Screenshot

ASP.Net Core MVC: AlphaNumeric TextBox Validation (Alphabets and Numbers) characters using Data Annotations and jQuery
 
 

Downloads

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