Hello,

I would like to create a new Html.Helper that renders as follows:

namespace MyNameSpace
{ 
public static class HtmlHelperExtensions
{
   public static string SolidMsgBox(this System.Web.Mvc.HtmlHelper htmlHelper, string text) 
   {
     return string.Format("<div class="Whatever"><div>{0}</div></div>", text);
   }
}
}

usage

Note make sure you reference MyNameSpace in your view to be able to see your new extension method

 <%= Html.SolidMsgBox("Hello") %>

 Is that what you mean?

Yes,

but can I use: <%= Html.SolidMsgBox("Hello", "", new { @class = "Message" }) %>

Where the attributes are added to the outside Div, i.e:

<div class="Message"><div>{0}</div></div>

Thanks,

Miguel

public static string SolidMsgBox(this System.Web.Mvc.HtmlHelper htmlHelper, string text, object attributes)
{
IDictionary<string, object> attributesDict = (IDictionary<string, object>)new RouteValueDictionary(attributes);
System.Web.Mvc.TagBuilder builder = new System.Web.Mvc.TagBuilder("div");
builder.MergeAttributes<string, object>(attributesDict);
builder.InnerHtml = string.Format("<div>{0}</div>", text);
return builder.ToString();
}

That's exactly what I was looking for. Thank you.

I am having only one problem. I created the file SolidMsgBox.cs and added the code there:

public static class HtmlHelperExtensions {
  public static string SolidMsgBox(this HtmlHelper helper, string name) {
    return SolidMsgBox(helper, name, null, null);
  }
  ' ...
}

Then I was creating a new .cs file for a new helper the same as this one and I got the following:

The namespace '<global namespace>' already contains a definition for 'HtmlHelperExtensions'

Does this mean that I need to place all my Helper extensions in the same file? Can't I place them in different files?

Thanks,

Miguel

No, problem. You can place your html extensions in as many different class names as you like. The important things are:

1) The class is static

2) The extension method is static

3) The extension method uses the this keyword on the first parameter of type of HtmlHelper

4) You reference the classes namespace from your view.

Please accept as answer if you feel like I covered everything.

 Thanks, Paul

 Paul,

 what I meant was instead of having the ToolTip inside a new class named HtmlHelperExtentions can I make my ToolTip method to some how extend the HtmlHelper, i.e., to be also inside "HtmlHelper'?

  public static class HtmlHelperExtensions {

    public static string ToolTip(this HtmlHelper helper, string name) {
      ...
    }
  ...

Would become:

   public static class HtmlHelper {

    public static string ToolTip(string name) {
      ...
    }
  ...

Under System.Web.MVC.

And if yes, should I do this?

Thanks,
Miguel

You can do that as the team have implemented HtmlHelper as a partial class. The code would look like: 

namespace System.Web.Mvc
{
    public partial class HtmlHelper
    {
        public string ToolTip(this HtmlHelper helper, string name)
        {
             ....Code
        }
    }
}

The reason that I implemented it as an extension method is that I think it is a dubious practice to implement your own custom code inside a Microsoft namespace.

The choice is yours though

PaulBlamire:

The reason that I implemented it as an extension method is that I think it is a dubious practice to implement your own custom code inside a Microsoft namespace.

The choice is yours though

But if I am extending a Helper, why not? Then they will all be in the same place ...

The same happens if I am extending some functionality in Generics like the PagedList ...

Should I add all my code into my own namespace?

I have seen different approaches and I am in the moment trying to organize my code so this is something I yet need to decide.

Thanks,

Miguel

Hi Miguel,

To be honest there is no technical reason not to do what you have suggested. It is my personal preference try to me absolutely clear when it is my code that is being invoked rather than framework code. Also I wouldn't want my co-workers blaming bugs in my custom code on the framework by accident.

But these kinds of decisions really are your choice, if the convenience of not having to reference an extra namespace makes a difference to you then there is nothing to stop you.

As the HtmlHelper will used almost exclusively in your view code you could simply add an entry to your web.config to save you referencing the namespace explicitly in every view

    <pages>
      <namespaces>
        <add namespace="Miguel.Mvc"/>
      </namespaces>
    </pages>