Question

I have a solution that has multiple projects in it, including a web application. I want MSBuild to execute "WebPublish" target against the web application project and "default target" for all other projects in the solution.

This MSDN article says that I can do it specifying the command line

msbuild SlnFolders.sln /t:NotInSlnfolder:Rebuild;NewFolder\InSolutionFolder:Clean

But I never could make it work – MSBuild return an error, something like "NotInSlnFolder:Rebuild" target does not exist. It does not matter what target to specify, Build, Rebuild or Clean – it does not work in any case.

How can I achieve my goal of specifying project-specific targets for a solution?

The MSDN documentation does not work. Or have I missed something?

Answer 1

NOTE: This workaround is not officially supported by Microsoft, so there is no guarantee that it will work forever.

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Short Answer

In folder with the SLN file, create the file before.{YourSolution}.sln.targets, with the following content: (Replace what in curly brackets to whatever you need.)

<?xml version="1.0" encoding="utf-8"?>
<Project ToolsVersion="4.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
  <Target Name="{MyCompany_MyProduct_WebApp:WebPublish}">
    <MSBuild
        Condition="'%(ProjectReference.Identity)' == '{$(SolutionDir)MyCompany.MyProduct.WebApp\MyCompany.MyProduct.WebApp.csproj}'"
        Projects="@(ProjectReference)"
        Targets="{WebPublish}"
        BuildInParallel="True"
        ToolsVersion="4.0"
        Properties="BuildingSolutionFile=true; CurrentSolutionConfigurationContents=$(CurrentSolutionConfigurationContents); SolutionDir=$(SolutionDir); SolutionExt=$(SolutionExt); SolutionFileName=$(SolutionFileName); SolutionName=$(SolutionName); SolutionPath=$(SolutionPath)"
        SkipNonexistentProjects="%(ProjectReference.SkipNonexistentProjects)" />
  </Target>
</Project>

After that you can execute the command line:

msbuild {YourSolution}.sln /t:{MyCompany_MyProduct_WebApp:WebPublish}

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Long Answer

If you add environment variable MSBUILDEMITSOLUTION, setting its value to 1, MSBuild will not delete temporary files generated for the solution and projects.

This will allow you to find {YourSolution}.sln.metaproj and {YourSolution}.sln.metaproj.tmp files generated in the solution folder, which are just standard MSBuild project files.

For MSBuild 3.5, the generated file is {YourSolution}.sln.cache and is retained regardless of environment variables. Analyzing those files, you will understand low-level details of the process and to see the customization opportunities available.

After executing MSBuild with some project-specific target in the .Metaproj file you will find out that the list of project-specific targets is hardcoded and only standard targets are supported (Build, Rebuild, Clean, Compile, Publish; note: Publish and WebPublish are not the same). MSBuild 3.5 only generates Clean, Rebuild and Publish targets as well as a target with just the project’s name that means “Build”.

You also can see that NotInSlnfolder:Rebuild is just a name of an autogenerated target. In reality MSBuild does not parse it and does not care about project names and location. Also note that the autogenerated target names specify the project name with solution folders hierarchy if it’s in one, e.g. SolFolder\SolSubfolder\ProjectName:Publish.

One more critically important thing you will find: The MSBuild Target Name does not support dots. All dots in project names are replaced with underscores. For example, for a project named MyCompany.MyProduct.Components you will have to specify in the command line:

/t:MyCompany_MyProduct_Components:Rebuild

That’s why even standard project-specific target Build didn’t work – my project name contained dots.

Analyzing file {YourSolution}.sln.metaproj.tmp, you will find out that at runtime it tries to import targets from file named before.{YourSolution}.sln.targets and after.{YourSolution}.sln.targets, if those files exist. This has a key to the workaround for this MSBuild limitation/bug.