Creating Custom Tag Helpers - (ASP.NET MVC Tag Helpers)

In ASP.NET MVC, Tag Helpers provide a powerful way to create reusable UI components and simplify the code required to generate HTML markup. While there are many pre-built Tag Helpers available in ASP.NET, it's sometimes necessary to create custom Tag Helpers to meet specific requirements. In this tutorial, we'll walk through the steps of creating custom Tag Helpers in ASP.NET MVC.

Syntax

To create a custom Tag Helper, you need to create a class that extends the TagHelper class and implements the ITagHelper interface. The syntax for creating a custom Tag Helper is as follows:

[HtmlTargetElement("tag-name", Attributes = "attribute-name")]
public class CustomTagHelper : TagHelper
{
    public override void Process(TagHelperContext context, TagHelperOutput output)
    {
        // code to generate HTML markup
    }
}

Example

Let's create an example custom Tag Helper that generates a link with custom CSS classes and a tooltip. First, we create a new class that extends the TagHelper class and implements the ITagHelper interface:

[HtmlTargetElement("custom-link")]
public class CustomLinkTagHelper : TagHelper
{
    public string Href { get; set; }
    public string Class { get; set; }
    public string Tooltip { get; set; }

    public override void Process(TagHelperContext context, TagHelperOutput output)
    {
        output.TagName = "a";
        output.Attributes.SetAttribute("href", Href);
        output.Attributes.SetAttribute("class", Class);
        output.Attributes.SetAttribute("data-toggle", "tooltip");
        output.Attributes.SetAttribute("title", Tooltip);

        output.Content.SetContent(output.GetChildContentAsync().Result.GetContent());
    }
}

In this example, we target the <custom-link> HTML tag with the HtmlTargetElement attribute. We also define three properties for the Href, Class, and Tooltip values. In the Process method, we generate HTML markup for an <a> tag and set its attributes using the values provided in the Tag Helper. We also use the ChildContent property to set the content of the <a> tag.

Explanation

In the example above, we create a custom Tag Helper using the TagHelper class and implement the ITagHelper interface. The custom Tag Helper targets the <custom-link> HTML tag using the HtmlTargetElement attribute. We also add several properties to the class that correspond to the attributes of the <custom-link> tag. In the Process method, we generate HTML markup for an <a> tag and set its attributes using the values provided in the Tag Helper.

Use

Custom Tag Helpers can be used to simplify the code required to generate HTML markup and create reusable UI components. They can also be used to enhance the functionality of existing HTML elements or create new ones.

Important Points

Here are some important points to keep in mind when creating custom Tag Helpers in ASP.NET MVC:

• A custom Tag Helper class must extend the TagHelper class and implement the ITagHelper interface.
• Attributes can be added to the HtmlTargetElement attribute to specify the target element and attribute names.
• Custom Tag Helpers can be used to generate HTML markup and set attributes for existing or custom HTML elements.

Summary

In this tutorial, we walked through the steps of creating custom Tag Helpers in ASP.NET MVC. We discussed the syntax, example, explanation, use, and important points of creating custom Tag Helpers. With this knowledge, you can create custom Tag Helpers in ASP.NET MVC to create reusable UI components and generate HTML markup more efficiently.