How to Auto-Run T4 Templates in Visual Studio Builds

In Visual Studio, a T4 text template is a mixture of text blocks and control logic that can generate a text file. The control logic is written as fragments of program code in Visual C# or Visual Basic.

The generated file can be text of any kind, such as a web page, or a resource file, or program source code in any language.

Read more here background here:

• https://docs.microsoft.com/en-us/visualstudio/modeling/code-generation-and-t4-text-templates?view=vs-2019

Set up your T4 template in your project

• Add reference to your T4 templates in your .csproj file:

  BackEnd.csproj
  1<ItemGroup>
  2     <Content Include="Models\Model.tt">
  3         <Generator>TextTemplatingFileGenerator</Generator>
  4         <LastGenOutput>Model.ts</LastGenOutput>
  5     </Content>
  6</ItemGroup>

  • Note: This is not supported in your .njsproj, so this needs to live in your .csproj

• Write your T4 Templates to write the output that you want.

  • Test this by right-clicking the .tt file in Visual Studio and choosing Run Custom Tool

Automate it

This is great, but requiring manual intervention for code generation is so 2019.

• Install NuGet package Mono.TextTransform

  • https://www.nuget.org/packages/Mono.TextTransform/

• Run your T4 Text Transforms after the C# code builds:

  • Add the following PostBuildEvent BackEnd.csproj:

  BackEnd.csproj
  1<PropertyGroup>
  2    <PostBuildEvent>"$(SolutionDir)packages\Mono.TextTransform.1.0.0\tools\TextTransform.exe" "$(ProjectDir)Models\Model.tt" -a=outDir!"$(TargetDir)$(ConfigurationName)\"</PostBuildEvent>
  3</PropertyGroup>

Success!

Now when you build, your generated output will be re-generated after the build succeeds. Whew! 😅

What about pre-build events?

If you need to run your T4 template before the build, such as for T4 MVC, you'll want to use a <PreBuildEvent> instead of the <PostBuildEvent> above in your .csproj file.