How to get a property from a task in a TFS build?

Question

I made a custom task in my TFS build to examine my project's GlobalAssemblyInfo.cs file in order to extract an attribute (AssemblyInformationalVersion to be exact) in order to use its value in naming a zip file that I make with the build.

<UsingTask TaskName="GetAssemblyInformationalVersion.GetAssemblyInformationalVersionTask"
         AssemblyFile="$(MSBuildExtensionsPath)\GetAssemblyInformationalVersion.dll" />

The .cs file for my DLL has these two properties:

[Required]
public String InfoFile { get; set; }
public String InfoVersion { get; set; }

Here is my call to my task:

<GetAssemblyInformationalVersionTask InfoFile="$(Path to file)\GlobalAssemblyInfo.cs" />

My intention is to pass in the assembly info file through the property InfoFile so that I can find what I want (which my C# code does) and set it to the property InfoVersion for me to reference in TFS by running it as a task. In principle, I would use the property InfoVersion to use in naming my zip file. For example,

"Package.$(some form of reference to InfoVersion).zip"

However, I have not been able to find a way to actually accomplish this.

My question is: How can I invoke the get part of my property in my task? It seems like it should be easy, since I have not found anything written about this sort of thing online, but any help will be much appreciated.

Answer 1

Your custom task, GetAssemblyInformationVersionTask, will need to have a property on it of type ITaskItem that is decorated with the [Output] attribute.

public class GetAssemblyInformationVersionTask
{
    [Output]
    public ITaskItem Version { get; set; }

    public override bool Execute()
    {
      // code to set Version 
      return true;
    }
}

Then you will be able to use it like so:

<GetAssemblyInformationVersionTask InfoFile="$(Path to file)\GlobalAssemblyInfo.cs">
        <Output TaskParameter="Version" ItemName="AssemblyVersion" />
 </GetAssemblyInformationVersionTask>

AssemblyVersion will be the item variable that will contain the value of the Version property of your task.

If you've not seen it, MSDN Best Practices for Reliable Builds, Part 2 touches on the subject of output parameters. I'll see if I can't find better examples online.

Thomas Ardal has another good sample of [Output] in a custom task here.

HTH,

Z