MSBuild conditions based on imported properties - visual-studio

Question

I have a solution that has multiple projects, and I'd like them all to be able to access a set of shared properties that have been defined once in a common file at the solution level.
This mostly works fine using the code below and I can use the imported properties in the BeforeBuild target, however the problem I'm having is that I can't use the imported properties in conditions.
So I have the following in a CommonSettings.targets file in the solution folder:
<Project xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
<Target Name="CommonSettingsTarget">
<PropertyGroup>
<MyCustomProperty>Sample</MyCustomProperty>
</PropertyGroup>
</Target>
</Project>
In my project file I have:
<Project ToolsVersion="14.0" DefaultTargets="Build" InitialTargets="CommonSettingsTarget" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
<Import Project="$(SolutionDir)CommonSettings.targets" />
<ItemGroup>
<EmbeddedResource Include="EmbeddedDocument.txt" Condition=" '$(MyCustomProperty)' == 'Sample' " />
</ItemGroup>
<Target Name="BeforeBuild">
<Message Text="MyCustomProperty='$(MyCustomProperty)'" Importance="high" />
</Target>
</Project>
In the above, I can see my imported property displayed in the output window as "MyCustomProperty='Sample'" which is great, however when it's used as part of a condition (to optionally include an embedded resource), the condition is never satisfied.
Is there any way to make the imported properties work with conditions?

Answer 1

As your ItemGroup is not within a target, but the PropertyGroup is, the CommonSettingsTarget has not yet been executed when your condition is evaluated and thus MyCustomProperty has not yet been defined.
The Message task is called from within the BeforeBuild target which depends on CommonSettingsTarget and thus MyCustomProperty has been defined when you create the message.
Think of the Import as copying the imported project into your project file. The result would be something like this:
<Project ToolsVersion="14.0" DefaultTargets="Build" InitialTargets="CommonSettingsTarget" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
<Target Name="CommonSettingsTarget">
<PropertyGroup>
<MyCustomProperty>Sample</MyCustomProperty>
</PropertyGroup>
</Target>
<ItemGroup>
<EmbeddedResource Include="EmbeddedDocument.txt" Condition=" '$(MyCustomProperty)' == 'Sample' " />
</ItemGroup>
<Target Name="BeforeBuild">
<Message Text="MyCustomProperty='$(MyCustomProperty)'" Importance="high" />
</Target>
</Project>
This is what happens:
You define a target CommonSettingsTarget which will define MyCustomProperty when it is executed. Not now.
You define the ItemGroup and therefore evaluate the condition. It returns false, because MyCustomProperty has not yet been defined.
You define a target BeforeBuild.
You run the initial target, i.e. CommonSettingsTarget. Now MyCustomProperty is defined.
You run the default target which depends on BeforeBuild and thus runs BeforeBuild. There you evaluate MyCustomProperty which has been defined in step 4.
As a solution, remove the CommonSettingsTarget target and define the PropertyGroup as a child of the Project in CommonSettings.targets instead:
<Project xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
<PropertyGroup>
<MyCustomProperty>Sample</MyCustomProperty>
</PropertyGroup>
</Project>
In your project file, you should remove the InitialTargets="CommonSettingsTarget" then.