DC.Build.Tasks

MSBuild task GetCurrentBuildVersion to auto generate version number in .NET Core projects (.csproj).

In new .NET Core .csproj files (VS 2017) we can no longer use AssemblyVersion attribute (in AssemblyInfo.cs) with star (*) to auto-generate version number:

[assembly: System.Reflection.AssemblyVersion("1.0.*")]

Error CS7034: The specified version string does not conform to the required format - major[.minor[.build[.revision]]]

I came up with solution that worked almost the same as old AssemblyVersion attribute.

Values for AssemblyVersion and AssemblyFileVersion is in MSBuild project .csproj file (not in AssemblyInfo.cs) as property FileVersion (generates AssemblyFileVersionAttribute) and AssemblyVersion (generates AssemblyVersionAttribute). In MSBuild process we use our custom MSBuild task to generate version numbers and then we override values of these FileVersion and AssemblyVersion properties with new values from task.

MSBuild task GetCurrentBuildVersion

MSBuild task is in DC.Build.Tasks.dll which is .NET Standard 1.3 class library. In this library is Task class named GetCurrentBuildVersion which inherit from Microsoft.Build.Utilities.Task class from Microsoft.Build.Utilities.Core NuGet package. It takes BaseVersion property (optional) on input and returns generated version in Version output property. The logic to get version numbers is same as .NET automatic versioning (Build number is days count since 1/1/2000 and Revision is half seconds since midnight).

Usage

Setup MSBuild in your .csproj project file to use GetCurrentBuildVersion task and set FileVersion and AssemblyVersion properties.

In .csproj file it looks like this:

<Project Sdk="Microsoft.NET.Sdk">
  <UsingTask TaskName="GetCurrentBuildVersion" AssemblyFile="$(MSBuildThisFileFullPath)\..\..\DC.Build.Tasks.dll" />
 
  <PropertyGroup>
    ...
    <AssemblyVersion>1.0.0.0</AssemblyVersion>
    <FileVersion>1.0.0.0</FileVersion>
  </PropertyGroup>
 
  ...
 
  <Target Name="BeforeBuildActionsProject1" BeforeTargets="BeforeBuild">
    <GetCurrentBuildVersion BaseVersion="$(FileVersion)">
      <Output TaskParameter="Version" PropertyName="FileVersion" />
    </GetCurrentBuildVersion>
    <PropertyGroup>
      <AssemblyVersion>$(FileVersion)</AssemblyVersion>
    </PropertyGroup>
  </Target>
 
</Project>

Importtant things here:

• Mentioned UsingTask imports GetCurrentBuildVersion task from DC.Build.Tasks.dll. It assumes that this dll file is located on parent directory from your .csproj file.
• Our BeforeBuildActionsProject1 Target that calls task must have unique name per project in case we have more projects in the solution which calls GetCurrentBuildVersion task.