Generated Files Output Configuration

May 26, 2026 · View on GitHub

By default, Roslyn source generators (including Facet) output generated files to the obj/Generated/ folder, which is hidden from the Solution Explorer. However, you can configure where generated files are written using standard MSBuild properties.

Making Generated Files Visible

To make generated files visible in your project and control where they are output, add the following properties to your .csproj file:

<PropertyGroup>
  <EmitCompilerGeneratedFiles>true</EmitCompilerGeneratedFiles>
  <CompilerGeneratedFilesOutputPath>Generated</CompilerGeneratedFilesOutputPath>
</PropertyGroup>

Configuration Options

Place generated files in a Generated folder within your project:

<PropertyGroup>
  <EmitCompilerGeneratedFiles>true</EmitCompilerGeneratedFiles>
  <CompilerGeneratedFilesOutputPath>Generated</CompilerGeneratedFilesOutputPath>
</PropertyGroup>

<!-- Exclude from compilation to avoid duplicate definitions -->
<ItemGroup>
  <Compile Remove="Generated\**" />
  <!-- Keep them visible in Solution Explorer -->
  <None Include="Generated\**" />
</ItemGroup>

This configuration:

  • Makes generated files visible in Solution Explorer
  • Allows you to browse and inspect generated code
  • Excludes them from compilation (they're already compiled as generated files)
  • Useful for debugging and understanding what code is being generated

2. Output to obj Folder (Default Behavior)

Keep generated files in the obj folder but make them visible:

<PropertyGroup>
  <EmitCompilerGeneratedFiles>true</EmitCompilerGeneratedFiles>
  <CompilerGeneratedFilesOutputPath>$(BaseIntermediateOutputPath)Generated</CompilerGeneratedFilesOutputPath>
</PropertyGroup>

This is what Facet's test projects use internally.

3. Output to Shared Project

Generate files in a separate shared project:

<PropertyGroup>
  <EmitCompilerGeneratedFiles>true</EmitCompilerGeneratedFiles>
  <CompilerGeneratedFilesOutputPath>..\MySharedProject\Generated</CompilerGeneratedFilesOutputPath>
</PropertyGroup>

Important: When outputting to a shared project, ensure the types being generated are partial so they can be merged with the declarations in your source project.

File Structure

By default, Facet emits two files per type: a *.Properties.g.cs file containing the property declarations (and XML doc comments) and a *.Mappings.g.cs file containing constructors, projections, and conversion methods. Generated files are organised by generator:

Generated/
├── Facet/
│   ├── Facet.Generators.FacetGenerator/
│   │   ├── UserDto.Properties.g.cs
│   │   ├── UserDto.Mappings.g.cs
│   │   ├── ProductDto.Properties.g.cs
│   │   ├── ProductDto.Mappings.g.cs
│   │   └── ...
│   ├── Facet.Generators.FlattenGenerator/
│   │   └── ...
│   └── Facet.Generators.GenerateDtosGenerator/
│       └── ...
└── OtherGenerator/
    └── ...

Opting Out of Split Output

If you prefer the previous single-file output ({Type}.g.cs) you can opt out globally:

<PropertyGroup>
  <Facet_SplitGeneratedFiles>false</Facet_SplitGeneratedFiles>
</PropertyGroup>

With false, all generated code for a type is written to a single {Type}.g.cs file as in previous versions.

Benefits of Visible Generated Files

  1. Debugging: Easier to see what code is being generated and debug issues
  2. Learning: Understand how Facet generates code by inspecting the output
  3. Code Reviews: Include generated files in code reviews if needed
  4. Documentation: Auto-generated code serves as documentation

Important Notes

  • Do NOT manually edit generated files - they will be overwritten on the next build
  • Generated files are recreated on every build based on your source code and attributes
  • Do NOT commit generated files to source control unless you have a specific reason (add to .gitignore)
  • When placing files in the project folder, always exclude them from compilation using <Compile Remove="Generated\**" />

Example .gitignore

If you choose to make generated files visible in your project, add this to your .gitignore:

# Facet generated files
Generated/
**/Generated/

Troubleshooting

Duplicate Type Definitions

If you see errors about duplicate type definitions, ensure you've excluded the Generated folder from compilation:

<ItemGroup>
  <Compile Remove="Generated\**" />
</ItemGroup>

Files Not Appearing

  1. Clean and rebuild your solution
  2. Verify EmitCompilerGeneratedFiles is set to true
  3. Check the output path exists and is accessible
  4. Ensure you're using a recent .NET SDK (6.0+)

Performance Considerations

Emitting generated files to disk has minimal performance impact. However, if you have thousands of generated files and are using source control, consider:

  • Keeping them in the obj folder (default)
  • Adding the output directory to .gitignore