How to synchronise the publish version to the assembly version in a .NET ClickOnce application?

sylvanaar's last line looks like the way to go, in my experience; but with the caveat that it is only available to deployed versions of the application. For debugging purposes, you might want something like:

    static internal string GetVersion()
    {
        if (ApplicationDeployment.IsNetworkDeployed)
        {
            return ApplicationDeployment.CurrentDeployment.CurrentVersion.ToString();
        }

        return "Debug";
    }

I modified my .csproj file to update the assembly version. I created a configuration called "Public Release" for this, but it's not required to do that.

  <Import Project="$(MSBuildBinPath)\Microsoft.CSharp.targets" />
  <!-- To modify your build process, add your task inside one of the targets below and uncomment it.
       Other similar extension points exist, see Microsoft.Common.targets.
  <Target Name="BeforeBuild">
  </Target>
  <Target Name="AfterBuild">
  </Target>
  -->
  <PropertyGroup Condition="'$(BuildingInsideVisualStudio)' == 'true'">
    <MSBuildCommunityTasksPath>$(SolutionDir)Tools\MSBuildCommunityTasks</MSBuildCommunityTasksPath>
  </PropertyGroup>
  <!-- Required Import to use MSBuild Community Tasks -->
  <Import Project="$(SolutionDir)Tools\MSBuildCommunityTasks\MSBuild.Community.Tasks.Targets" Condition="'$(BuildingInsideVisualStudio)' == 'true'" />
  <Target Name="BeforeCompile" Condition="'$(BuildingInsideVisualStudio)|$(Configuration)' == 'true|PublicRelease'">
    <FormatVersion Version="$(ApplicationVersion)" Revision="$(ApplicationRevision)">
      <Output TaskParameter="OutputVersion" PropertyName="AssemblyVersionToUse" />
    </FormatVersion>
    <AssemblyInfo CodeLanguage="CS" OutputFile="$(ProjectDir)Properties\VersionInfo.cs" AssemblyVersion="$(AssemblyVersionToUse)" AssemblyFileVersion="$(AssemblyVersionToUse)" />
  </Target>

The published version may be:

ApplicationDeployment.CurrentDeployment.CurrentVersion

I would like to expand on Sylvanaar's answer, as some of implementation details weren't obvious to me. So:

1. Manually install community build tasks found at: https://github.com/loresoft/msbuildtasks/releases Note: Don't install by nuget if you clean your packages, as the build will fail before getting a chance to restore the packages, since msbuildtasks are referenced as a task in the build file. I put these in folder next to solution file called .build

2. Add a completely empty file to your projects properties folder called VersionInfo.cs

3 Remove these lines if they exist in AssemblyInfo.cs

[assembly: AssemblyVersion("1.0.*")]
[assembly: AssemblyFileVersion("1.0.*")]

4 Modify your csproj file

  <!-- Include the build rules for a C# project. -->
  <Import Project="$(MSBuildToolsPath)\Microsoft.CSharp.targets" />

  <!--INSERT STARTS HERE-->
  <!--note the use of .build directory-->
  <PropertyGroup Condition="'$(BuildingInsideVisualStudio)' == 'true'">
    <MSBuildCommunityTasksPath>$(SolutionDir)\.build\MSBuildCommunityTasks</MSBuildCommunityTasksPath>
  </PropertyGroup>
  <!-- Required Import to use MSBuild Community Tasks -->
  <Import Project="$(SolutionDir)\.build\MSBuild.Community.Tasks.targets" Condition="'$(BuildingInsideVisualStudio)' == 'true'" />
  <Target Name="BeforeCompile" Condition="'$(BuildingInsideVisualStudio)|$(Configuration)' == 'true|Release'">
    <FormatVersion Version="$(ApplicationVersion)" Revision="$(ApplicationRevision)">
      <Output TaskParameter="OutputVersion" PropertyName="AssemblyVersionToUse" />
    </FormatVersion>
    <AssemblyInfo CodeLanguage="CS" OutputFile="$(ProjectDir)Properties\VersionInfo.cs" AssemblyVersion="$(AssemblyVersionToUse)" AssemblyFileVersion="$(AssemblyVersionToUse)" />
  </Target>

5 Use a method like the following to access the version text:

public string Version()
{
    Version version = null;

    if (ApplicationDeployment.IsNetworkDeployed)
    {
        version = ApplicationDeployment.CurrentDeployment.CurrentVersion;
    }
    else
    {
        version = typeof(ThisAddIn).Assembly.GetName().Version;
    }

    return version.ToString();
}