Walkthrough: Linking a Content Type to a File Name Extension

Article
11/15/2016

Note

This article applies to Visual Studio 2015. If you're looking for the latest Visual Studio documentation, see Visual Studio documentation. We recommend upgrading to the latest version of Visual Studio. Download it here

You can define your own content type and link a file name extension to it by using editor Managed Extensibility Framework (MEF) extensions. In some cases, the file name extension has already been defined by a language service; nevertheless, to use it with MEF you still must link it to a content type.

Prerequisites

Starting in Visual Studio 2015, you do not install the Visual Studio SDK from the download center. It is included as an optional feature in Visual Studio setup. You can also install the VS SDK later on. For more information, see Installing the Visual Studio SDK.

Creating a MEF Project

Create a C# VSIX project. (In the New Project dialog, select Visual C# / Extensibility, then VSIX Project.) Name the solution ContentTypeTest.
In the source.extension.vsixmanifest file, go to the Assets tab, and set the Type field to Microsoft.VisualStudio.MefComponent, the Source field to A project in current solution, and the Project field to the name of the project.

Defining the Content Type

Add a class file and name it FileAndContentTypes.
Add references to the following assemblies:
1. System.ComponentModel.Composition
2. Microsoft.VisualStudio.Text.Logic
3. Microsoft.VisualStudio.CoreUtility

Add the following using directives.

using System.ComponentModel.Composition;  
using Microsoft.VisualStudio.Text.Classification;  
using Microsoft.VisualStudio.Utilities;

Declare a static class that contains the definitions.

internal static class FileAndContentTypeDefinitions  
{. . .}

In this class, export a ContentTypeDefinition named "hid" and declare its base definition to be "text".

internal static class FileAndContentTypeDefinitions  
{  
    [Export]  
    [Name("hid")]  
    [BaseDefinition("text")]  
    internal static ContentTypeDefinition hidingContentTypeDefinition;  
}

Linking a File Name Extension to a Content Type

To map this content type to a file name extension, export a FileExtensionToContentTypeDefinition that has the extension ".hid" and the content type "hid".

internal static class FileAndContentTypeDefinitions  
{  
     [Export]  
     [Name("hid")]  
     [BaseDefinition("text")]  
    internal static ContentTypeDefinition hidingContentTypeDefinition;  

     [Export]  
     [FileExtension(".hid")]  
     [ContentType("hid")]  
    internal static FileExtensionToContentTypeDefinition hiddenFileExtensionDefinition;  
}

Adding the Content Type to an Editor Export

Create an editor extension. For example, you can use the margin glyph extension described in Walkthrough: Creating a Margin Glyph.
Add the class you defined in this procedure.
When you export the extension class, add a ContentTypeAttribute of type "hid" to it.
```
[Export]  
[ContentType("hid")]  
```