MsBuild condition for new ("sdk-style") vs. old project format

Question

I want to write an msbuild "include" (.props) file that is to be imported in both the new ("sdk-style") projects as well as the old ones.

Is there a way to find out into which type of project the .props file is imported so I could use that in a condition? For example,

<PropertyGroup Condition="'$(ProjectType)'=='sdk'">
   <SomeProperty>SomeValue</SomeProperty>
</PropertyGroup>

Answer 1

I encountered this same need in my project. At first I went with the solution @wexman, but I found that variable not to be reliable. I considered the approach of opening the csproj file and using regexes to look for the SDK attribute, but it felt too brittle to me - especially given that the SDK can be specified either in an element or an attribute. Finally I created a build with binary logging turned on (option /bl) and went hunting through the various files that get imported when doing a build of an SDK-style project.

I discovered the property UsingMicrosoftNETSdk which is set to true in the props file which auto-imports Microsoft.Common.props when you are using an SDK-style project. This auto-import (which leads to the auto-import of Directory.Build.props seems to be one of the most important defining characteristics of SDK-style projects, and the name of the property makes it look like something more likely to stick around.

So in the end my solution was to have:

Condition="'$(UsingMicrosoftNETSdk)' == 'true'"

(or its inverse) as the reliable way to determine which type of project is in use.

Answer 2

I seem to have found a working solution. I'm checking against the property $(_PlatformWithoutConfigurationInference) declared in Microsoft.NET.Sdk.Props. If it is not empty, I'll be dealing with an sdk style project, if it is empty, it's a legacy project:

<Project>

  <PropertyGroup>
    <ProjectStyle Condition="'$(_PlatformWithoutConfigurationInference)'!=''">sdk</ProjectStyle>
    <ProjectStyle Condition="'$(_PlatformWithoutConfigurationInference)'==''">legacy</ProjectStyle>
  </PropertyGroup>

  <Target Name="PreBuild" BeforeTargets="PreBuildEvent">
    <Message Importance="High" Text="$(MsBuildProjectName) is a $(ProjectStyle) style project" />
  </Target>

</Project>