Summary of Metadata of items - Sum of ItemXYZ.Value

[MeikTranel]

Is there any way to resolve the sum of all Values here?

<ItemGroup>
  <ItemXYZ Include="A" Value="5" />
  <ItemXYZ Include="B" Value="2" />
  <ItemXYZ Include="C" Value="3" />
</ItemGroup>

[jrdodds]

Are you asking how to sum the numbers, i.e. 5 + 2 + 3 = 10?

Here is a solution that uses an inline task.

<Project xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
  <ItemGroup>
    <ItemXYZ Include="A" Value="5" />
    <ItemXYZ Include="B" Value="2" />
    <ItemXYZ Include="C">
      <Value>3</Value>
    </ItemXYZ>
  </ItemGroup>

  <Target Name="Main">
    <Sum Addends="@(ItemXYZ->Metadata('Value'))">
      <Output TaskParameter="Total" PropertyName="Sum" />
    </Sum>
    <Message Text="Sum = $(Sum)" />
  </Target>

  <UsingTask TaskName="Sum" TaskFactory="RoslynCodeTaskFactory" AssemblyFile="$(MSBuildToolsPath)\Microsoft.Build.Tasks.Core.dll">
    <ParameterGroup>
      <Addends ParameterType="Microsoft.Build.Framework.ITaskItem[]" Required="true" />
      <Total ParameterType="System.Int32" Output="true" />
    </ParameterGroup>
    <Task>
      <Code Type="Fragment" Language="cs">
        <![CDATA[
            Total = 0;
            foreach (var addend in Addends)
            {
                if (int.TryParse(addend.ItemSpec, out int result))
                {
                    Total += result;
                }
            }
        ]]>
      </Code>
    </Task>
  </UsingTask>
</Project>

The Sum task takes an ItemGroup and returns the sum of the items that can be parsed to integers.

The Sum task just generically uses the ItemSpec. Your example ItemGroup has a metadata value named 'Value'. The Metadata function is used to create a new ItemGroup that is the values of the 'Value' metadata, @(ItemXYZ->Metadata('Value')).

[rainersigwald]

Yeah, IMO this is pretty solidly in the "even if you can figure out a way to do it in MSBuild XML, everyone will be happier if you write a task" category.

[jrdodds]

Yeah, I rather quickly reached the conclusion to write a task.

[MeikTranel]

Yeaaaaaaaah i was hoping for a shorter syntax but the task works of course. my use case is that i have a ToolTask derived testrunner that returns report items with a shorthand summary of all outcomes inside the metadata of that report. I send that metadata as telemetry to an elk backend and i wanted to send another item summing the entire testrun for all test suites - problem is that i have like NUnit.xml amounts of outcomes which means with this solution i would have like 30 lines of xml just to generate the properties.

Thanks for lending me some brain cycles tho.