Write custom html helper

Write custom html helper

Creating and Using a Helper in an ASP.NET Web Pages (Razor) Site,Configuration

WebMar 24,  · In blogger.com Core there is no concept of HTML Helper like in MVC. What are TagHelpers? TagHelpers can be seen as the evolution of HTML helpers which WebFeb 2,  · MVC provides many HTML helper methods. It also provides facility to create your own HTML helper methods. Once you create your helper method you can reuse it WebMay 11,  · blogger.com MVC providesthree ways to define the custom html helper. Using Static Methods; Using Extension Methods; Using the @helper. Using Static WebCreate Custom HTML Helper in blogger.com MVC using Extension Method If we create an extension method, it will be available in the helper method of the view. E.g., WebNov 29,  · HTML Helpers are managed within View to execute HTML content. We can use HTML Helpers to implement a method that returns a string. This tutorial discusses ... read more

MVC provides many HTML helper methods. It also provides facility to create your own HTML helper methods. Once you create your helper method you can reuse it many times. There are two ways in MVC to create custom Html helpers as below. Adding extension method for HtmlHelper class We can create our own HTML helper by writing extension method for HTML helper class. These helpers are available to Helper property of class and you can use then just like inbuilt helpers. Example Add new class in MVC application and give it meaningful name. As we are going to create extension method make this class static. Write the following code in class:. The property to be used to create the HTML is passed to the method as a lambda expression. It could also be possible to specify id, name and various other HTML attributes using these helper methods.

Following HTML helpers are available to be used with strongly typed views:. If we want to create our own HTML helpers than that can also be done very easily. There are quite a few ways of creating custom helpers. lets look at all the possible methods. Let us try to create a simple HTML helper method which will create a marked HTML label. There is a new mark tag in HTML5 specifications. Let us try to create a label which create a label then mark it using the HTML5 mark tag. In this approach we can simply create a static class with static method which will return the HTML string to be used at the time of rendering.

In this approach we will write a simple extension method for the built in html helper class. this will enable us to use the same Html object to use our custom helper method. This method is pretty specific to razor view engine. Let us see how this can be done. We need to write this method in the view itself. Note: By default these helpers will be available in the view they are defined in. Make sure you have the right attributes set for the right elements. Please add suggestions if needs improvement or give your votes if it looks good.

Stack Overflow for Teams — Start collaborating and sharing organizational knowledge. Create a free Team Why Teams? Learn more about Collectives. Learn more about Teams. Create Custom HTML Helper in ASP. Net Core Ask Question. Asked 6 years ago. Modified 1 month ago. Viewed 59k times. net-core asp. Improve this question. edited Mar 25, at Aran Mulholland asked Feb 4, at Duefectu Duefectu 1, 4 4 gold badges 19 19 silver badges 37 37 bronze badges. Add a comment. Sorted by: Reset to default. Highest score default Trending recent votes count more Date modified newest first Date created oldest first. So for. Instead of for. Improve this answer. edited Dec 6, at answered Dec 4, at dougajmcdonald dougajmcdonald Didn't notice that distinction in my error, should have tried the interface.

HTML Helpers look to be supported in ASP. Looking at the ASP. NET Core source they work fairly similarly to older versions of ASP. cs Example MyHTMLHelpers. cs: using Microsoft. Html; using Microsoft. Rendering; using System; namespace MyApp. cshtml second line is the important change : using MyApp using MyApp. TagHelpers MyView. edited Mar 19, at answered Apr 20, at Akaoni Akaoni 1 1 gold badge 10 10 silver badges 13 13 bronze badges. Src code link is old Current link is: github. this should be on ms help and doc pages, havnt even tired yet but i can tell this is what i was looking for. grrrr ms update you stuff with examples like this. Wow, this is easy yet took me and Google an hour to find. Needed to output raw html in dotnetcore 2. Here is an example for.

Net Core 2 using TagBuilders using Microsoft. Rendering; using System. WriteTo writer, System. Default ; br. ToString ; } return new HtmlString result ; }. answered Aug 8, at René René 3, 1 1 gold badge 19 19 silver badges 33 33 bronze badges. I was missing the WriteTo part.

In the last tutorial we covered Built-In Tag Helpers in ASP. NET Core. Now we will learn to create Custom Tag Helper for transforming the html elements with C codes. We will take a lot of examples so make sure to go through each of the sections on this tutorial. Start by creating a CustomTagHelpers folder inside the root folder of the application. Next, add a class called BackgroundColorTH. cs to this folder. The code for this class is given below:. Some examples are:. The custom tag helper class derives from TagHelper base class. We have included a string property called BackgroundColor. The DOT NET runtime will transfer a value from razor view to this property.

DOT NET will inspect all the properties of the Custom Tag Helper class and transfer the values to these properties from the view if their names matches the attribute names applied on the HTML elements. DOT NET will also convert these values to the type of the property defined on the class. The BackgroundColor property value will be automatically assigned the value danger. There is a naming convention rule for attributes which is that the name of a attribute should be in html style like background-color. We cannot have the name starting with asp- or data-. The Tag Helper also has a function Process which overrides the function of the base class. This function adds the CSS class attribute with value btn-btn-{BackgroundColor} to html elements having the background-color attribute. cshtml file by adding the following code to it:.

The first part TagHelpers. It means all the files inside the TagHelpers. CustomTagHelpers namespace. The second part specifies the assembly name which is the name of the project. Here the project name is TagHelpers and can be different in your case. Now we can see the working of the Custom Tag Helper we just created. So we go to the Create View of the Home Controller and replace the button with the following code:. You will find the Red add button on the View, check the image below:. The btn-danger is a bootstrap class for giving red background color and so the button becomes red.

Why this happens? So the Custom Tag Helper class BackgroundColor property automatically received the value of the attribute i. Next the Process function adds the CSS class btn btn-{property value} to the button which becomes btn btn-danger. Tag Helpers receive information about the element which they are transforming through TagHelperContext class object. It is provided as the first parameter of the Process function. The TagHelperOutput class is provided as the 2nd parameter of the Process function. We can manage the scope of a Tag Helper i. controlling to which element the tag helper applies. Our Custom Tag Helper contains [HtmlTargetElement ] attribute.

It tells that the tag helper can be applied to any HTML element that contains the background-color attribute. We can add many more restriction. In the below code the restriction added is — the tag helper applies to any button element that contains background-color attribute. Next we can add a condition that the tag helper applies to any button that contains background-color attribute and it should also be contained inside a parent of type form. Note : You can also apply more than one [HtmlTargetElement ] attribute to the tag helper. The below Tag Helper can be applied to both button and anchor tags that have background-color attribute. We can also apply Tag Helpers to Custom HTML Elements and transform them to any HTML element.

However with Custom Tag Helper we can transform this custom HTML element to a HTML button. Create AspButtonTH. cs class inside the CustomTagHelpers folder and add the following code to the class:. The attribute [HtmlTargetElement "aspbutton" ] specifies that the custom tag helper will apply to aspbutton element. We added 2 Properties to the AspButtonTH. cs class, these are — Type and BackgroundColor. These properties will receive values from the type and background-color attributes of the custom HTML element. cshtml , replace the button code with the below code of this custom html element. See the image below:. The PreElement and PostElement properties of the TagHelperOutput class is used to add elements before and after the output element.

To help understand them, create a new file inside the CustomTagHelpers folder and name it PrePostElementTH. Add the following code to it:. This Tag Helper applies to the div element that has the pre-post attribute. The tag helper uses the PreElement and PostElement properties to add a header and a footer element that surrounds the output element. We have used the TagBuilder class of the namespace Microsoft. Rendering to create the HTML elements. The elements created by using TagBuilder class are:. There are optional bool attributes called add-header and add-footer that are used for specifying whether to exclude the header or the footer, default is to include both header and footer.

cshtml view by putting the RenderBody directive inside a div with pre-post attribute. This will apply the custom tag helper. See the code below. There are 2 properties — PreContent and PostContent that are used to insert contents inside the output element. Go to the CustomTagHelpers folder and add a new PrePostContentTH. cs file to it. Next add the following code to it:. This tag helper operates on td element that has underline attribute and it inserts u html element around it. To test it add underline attribute to one of the table cells in the Index View :. Run your application and you will see the name column in the Index View is now underlined.

This is shown in the image below:. The TagHelperContext. Items property is used to coordinate between tag helpers that operate on elements and those that operate on their descendants. To demonstrate this thing, create a new class file called CoordinateTagHelpers. cs file inside the CustomTagHelpers folder and add the following code to it:. Now to test this functionality — replace the button on the Create View with the following code:. Now you will see this time button and anchor tags are given the secondary bootstrap class. Inside the tag helpers we can get the details of the view that is being rendered i.

the View Context Data. This View Context Data includes information about routing, ViewData, ViewBag, TempData, ModelState, current HTTP request , etc. To get View Content Data add a property by name ViewContextData and decorate it with 2 attributes as shown below:. The ViewContext attribute denotes that the value of this property should be assigned the value of ViewContext object , when a new instance of the Tag Helper class is created. The HtmlAttributeNotBound attribute tells to not assign a value to this property if there is a view-context attribute given on the HTML element.

Let us now create a tag helper that gets View Content data. So add a class called FormTH. cs inside the CustomTagHelpers folder. Then add the following code to it. This tag helper targets all the form elements. Inside the Process method I get the IUrlHelper object from the urlHelperFactory. GetUrlHelper method. The IUrlHelper class is used to build URL based on routing data. Next, go to Create View and change the form tag to contain just method attribute like shown below. This clearly shows that my Tag helper has automatically added the action attribute with a perfect URL based on the routing system. The SupressOutput method of the TagHelperOutput class prevents the output element from being included in the View.

Let us show this by making a new custom tag helper. This tag helper will show a div only for request to a given action method.

An Absolute Beginner's Tutorial on HTML Helpers and Creating Custom HTML Helpers in ASP.NET MVC,Understanding HTML Helpers

WebMay 14,  · Registering the Custom Tag Helper. The final part is registering your Custom Tag Helper in the blogger.com file by adding the following code to it: WebMay 11,  · blogger.com MVC providesthree ways to define the custom html helper. Using Static Methods; Using Extension Methods; Using the @helper. Using Static WebMar 24,  · In blogger.com Core there is no concept of HTML Helper like in MVC. What are TagHelpers? TagHelpers can be seen as the evolution of HTML helpers which WebFeb 2,  · MVC provides many HTML helper methods. It also provides facility to create your own HTML helper methods. Once you create your helper method you can reuse it WebCreate Custom HTML Helper in blogger.com MVC using Extension Method If we create an extension method, it will be available in the helper method of the view. E.g., WebNov 29,  · HTML Helpers are managed within View to execute HTML content. We can use HTML Helpers to implement a method that returns a string. This tutorial discusses ... read more

Note : You can also apply more than one [HtmlTargetElement ] attribute to the tag helper. So I decided to use the ability of Razor pages to now support injecting services that have been registered for dependency injection. NET MVC providesthree ways to define the custom html helper. In this approach we will write a simple extension method for the built in html helper class. Full Stack Web Developer Course To become an expert in MEAN Stack View Course. Welcome to YogiHosting - A Programming Tutorial Website. net mvc with example.

In MVC, HTML Helper can be considered as a method that returns you a string. Read in English Save Table of contents Read in English Save Edit Print. Download PDF. We write custom html helper add many more restriction. NET MVC framework contains a small set of helpers. Related Tutorials: DbContext Class in Entity Framework Core.