Wix conditionals and preprocessor variables

Question

I want to change the value of a Wix variable depending on whether a value is defined or otherwise. In my wixproj I have:

  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'TFS Live|x86' ">
    <OutputPath>bin\$(Platform)\$(Configuration)\</OutputPath>
    <IntermediateOutputPath>obj\$(Platform)\$(Configuration)\</IntermediateOutputPath>
    <WixVariables>LIVE</WixVariables>
    <DefineConstants>LIVE</DefineConstants>
  </PropertyGroup>

...and in my wxs I have:

<?ifdef LIVE ?>
<?define binaryPath = "C:\Builds\5\IT Aerodynamics\RBT.TestSpec.LiveRelease\Binaries" ?>
<?else?>
<?define binaryPath = "C:\Builds\5\IT Aerodynamics\RBT.TestSpec.CI\Binaries" ?>
<?endif?>

...but when I build the appropriate configuration, the ifdef never fires. I always get the second value for binaryPath. Any suggestions as to what I'm doing wrong?

Answer 1

That code works for me. One thing to check is that you don't have another DefineConstants MSBuild Property later in the .wixproj that doesn't look like:

<DefineConstants>$(DefineConstants);OtherVars=Value</DefineConstants>

The default .wixproj template creates projects where the Debug preprocessor variable is defined like:

<DefineConstants>Debug</DefineConstants>

And that will overwrite DefineConstants defined higher in the project for debug builds. Otherwise, everything looks fine.

Answer 2

One more thing, in addition to the @RobMensching answer.

If you build your solution using command line and msbuild, and if you define your DefineConstants in that build command, all your defines in projects will be overridden with those defined in command line:

msbuild Your.sln /t:Build
        /p:Configuration=TFSLive
        /p:Platform=x86
        /p:DefineConstants=Your;Defines;Here