程序集HintPaths的C＃csproj文件“选择”元素

Question

Is it possible to use the Choose/When/Otherwise elements on a reference hintpath?

Something like this:

<ItemGroup>
  <Reference Include="SharedLib...">
<SpecificVersion>False</SpecificVersion>
<Choose>
  <When Condition="Exists('..\..\SharedLib\bin\Debug')">
        <HintPath>..\..\SharedLib\bin\Debug\SharedLib.dll</HintPath>
  </When>
  <Otherwise>
         <HintPath>.\SharedLib.dll</HintPath>
  </Otherwise>
</Choose>
  </Reference>
</ItemGroup>

But I get errors like ...required attribute "Include" is empty or missing from element "ItemGroup"

Other attempts/version have yielded similar errors such as ...The "Choose" item metadata name is reserved and cannot be used.

This makes me think I canNOT use the "Choose" element INSIDE of an ItemGroup element.

I welcome clarification. See attached samples of the errors. Visual Studio csproj Errors when loading project

Answer 1

I don't think you can put just the HintPath in the Choose. You have to put the entire ItemGroup within the When and Otherwise. Like this:

<Choose>
  <When Condition="Exists('..\..\SharedLib\bin\Debug')">
    <ItemGroup>
      <Reference Include="SharedLib...">
        <SpecificVersion>False</SpecificVersion>
        <HintPath>..\..\SharedLib\bin\Debug\SharedLib.dll</HintPath>
      </Reference>
    </ItemGroup>
  </When>
  <Otherwise>
    <ItemGroup>
      <Reference Include="SharedLib...">
        <SpecificVersion>False</SpecificVersion>
        <HintPath>.\SharedLib.dll</HintPath>
      </Reference>
    </ItemGroup>
  </Otherwise>
</Choose>