Replacement for @helper in ASP.NET Core

Question

So far, i don\'t think ViewComponent solves that neither does TagHelper. Is there any replacement to this? Something that takes parameters and retu

Answer 1

@{
    Func<String, IHtmlContent> foo = @<div>Say @item</div>;
}

Answer 2

The @helper directive was removed since it was incomplete and its current design did not fit in the new 'ASP.NET 5 way'. One of the reasons is that helpers should be declared in the App_Code folder while ASP.NET 5 has no concept of special folders. Therefore the team decided to temporarily remove the feature.

There are plans to bring it back in the future though. See this and this.

Answer 3

How about using partials to recreate reusable tags?

MyProject/Views/Shared/_foo.cshtml

@model string

<div>@Model</div>

MyProject/Views/Courses/Index.cshtml

@{
    Layout = "_Layout";
}

<div>
   <partial name="_foo" model="foo" />
   <partial name="_foo" model="bar" />
   <partial name="_foo" model="baz" />
</div>

Answer 4

For .NET Core 3, you can use local functions:

@{
    void RenderName(string name)
    {
        <p>Name: <strong>@name</strong></p>
    }

    RenderName("Mahatma Gandhi");
    RenderName("Martin Luther King, Jr.");
}

https://docs.microsoft.com/en-us/aspnet/core/mvc/views/razor?view=aspnetcore-3.1#razor-code-blocks

Answer 5

According to the following Github issue, it looks like @helper is coming back and will be included in asp .net core 3.0.0 preview 4.

https://github.com/aspnet/AspNetCore/issues/5110

UPDATE

Starting in asp .net core 3, you can now define a local function within a Razor code block.

@{
    void RenderName(string name)
    {
        <p>Name: <strong>@name</strong></p>
    }

    RenderName("Mahatma Gandhi");
    RenderName("Martin Luther King, Jr.");
}

https://docs.microsoft.com/en-us/aspnet/core/mvc/views/razor?view=aspnetcore-3.1#razor-code-blocks

Alternatively you can use the @functions directive like this:

@{
    RenderName("Mahatma Gandhi");
    RenderName("Martin Luther King, Jr.");
}

@functions {
    private void RenderName(string name)
    {
        <p>Name: <strong>@name</strong></p>
    }
}

https://docs.microsoft.com/en-us/aspnet/core/mvc/views/razor?view=aspnetcore-3.1#functions

Answer 6

You can easily replace that "feature" with a ViewComponent (and a TagHelper if you want). ASP.NET Core is much more friendly to web designers, and the ViewComponents allow you to write HTML without any (weird to most) razor code.

For example:

1. Create a SayComponent : ViewComponent class:

   public class SayComponent : ViewComponent
   {
       public void Render(string message)
       {
           return View(message);
       }
   }
   

2. Create a View file under Views/Shared/Say/Default.cshtml with just

   @model string
   
   <div>Message: @Model.</div>
   

3. And call it:

   @await Component.RenderAsync("Say", "some message")
   

For a better experience, add this to your _ViewImports.cshtml file:

@addTagHelper *, YourSolutionName

And then you can use it as a tag helper:

<vc:say message="some message"></vc:say>