How do I inform dependent projects that an output must be copied local when they use ProjectReference? - visual-studio

Question

I have two projects, let's call them Project A and Project B.
Project A has a CopyToOutputDirectory content item, as follows:
<ItemGroup>
<Content Include="MyExampleDependency.txt">
<Link>MyFunOutputLocation\MyExampleDependency.txt</Link>
<CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
</Content>
</ItemGroup>
Project B references Project A:
<ItemGroup>
<ProjectReference Include="..\..\Shared\Project A.csproj">
<Project>{My GUID here</Project>
<Name>Project A</Name>
</ProjectReference>
</ItemGroup>
When I build Project B, it is smart enough to copy the .dll produced by Project A, as well as this text file, to the output. That is, I end up with something like this when I build Project B:
bin\Project A\Project A.dll
bin\Project A\MyFunOutputLocation\MyExampleDependency.txt
bin\Project B\Project A.dll
bin\Project B\Project B.exe
bin\Project B\MyFunOutputLocation\MyExampleDependency.txt
I have a new dependency that I want to start generating in Project A; for example from a T4 transform. This could be a file I generate with an <Exec task, or a file generated by some custom target, or similar. For example:
<ItemGroup>
<Content Include="Foo.tt">
<Generator>TextTemplatingFileGenerator</Generator>
<OutputFilePath>$(OutDir)</OutputFilePath>
<LastGenOutput>Foo.xml</LastGenOutput>
</Content>
</ItemGroup>
Now when I build I end up with something like this:
bin\Project A\Project A.dll
bin\Project A\Foo.xml <-- Not copied to Project B!
bin\Project A\MyFunOutputLocation\MyExampleDependency.txt
bin\Project B\Project A.dll
bin\Project B\Project B.exe
bin\Project B\MyFunOutputLocation\MyExampleDependency.txt
Note that the generated file which is required for Project A.dll to work is not being copied alongside that dll when it gets copied into Project B. How do I inform Project B that it needs to copy this file from Project A (without editing Project B's .csproj file)?

Answer 1

If it's just a design-time Foo.tt output then it's as simple as expanding it in Solution Explorer and marking Foo.txt with appropriate Copy To Output Directory, just remember to mark it again if you ever change the extension as that'll delete and read it into the itemgroup losing the CopyToOutputDirectory metadata.
If it's an outside task, then you need to hook into a delayed event (so it doesn't pollute explorer on load or even error on clean) in Project A and add it to Content preferably with a wildcard or exists condition. Keep in mind that event you choose needs to run after your custom task but before _CopyFilesMarkedCopyLocal, e.g. if you create a file in PreBuildEvent of Project A and hook into BeforeBuild it won't work on clean build on Project B, you'd have to rebuild it again as BeforeBuild runs first and won't find anything at point of evaluation.
Project A.csproj
<Target Name="BeforeBuild">
<ItemGroup>
<Content Include="$(OutputPath)\Bar.txt" Condition="Exists('$(OutputPath)\Bar.txt')">
<Link>Bar.txt</Link>
<CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
</Content>
</ItemGroup>
</Target>
Edit:
Try the following.
In Project A define a Foo target for delayed/ondemand inclusion of the T4 output.
<Target Name="Foo">
<ItemGroup>
<Content Include="Foo.xml">
<CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
</Content>
</ItemGroup>
</Target>
You said you're transforming on build, so somewhere in the project you have the TextTemplating import that defines Transform target and its dependencies.
<PropertyGroup>
<TransformOnBuild>true</TransformOnBuild>
</PropertyGroup>
<Import Project="$(MSBuildExtensionsPath)\Microsoft\VisualStudio\v12.0\TextTemplating\Microsoft.TextTemplating.targets" />
Hook into one of them, i.e. AfterTransform, after the .targets import.
<PropertyGroup>
<AfterTransform>$(AfterTransform);Foo</AfterTransform>
</PropertyGroup>
That'll cover 90% of cases, the 9% left is building Project B directly in Visual Studio individually of Project A. The Rebuild would work out right thanks to AfterTransform but we need to hook into the Import since as you saw BeforeBuild is not executed as there are no changes and Visual Studio caches everything. We do this with InitialTargets on Project A.
<Project InitialTargets="Foo"
The final 1% is when you delete the .xml manually and build again as oppose to rebuild, but it's identical behaviour to deleting the .pdb, cached VS build will copy it again only if the .dll itself is missing or different.