Wouldn’t it be great if we could get Visual Studio to do this for us automatically on build?  I thought so too, so I’ve written a little app to do it

Getting set up with “When The Version”

1. Go get a copy of “When The Version” (WTV.exe) from the GitHub download page (or you can build it from the source if you prefer)
2. Drop it somewhere on your PC
3. Now, in your Visual Studio project, expand the Properties and duplicate the AssemblyInfo.cs / .vb file – I rename the duplicate to be AssemblyInfo.Template.cs:

4. Edit the AssemblyInfo.Template.cs file, putting in the placeholders for the date parts like so:

// Version information for an assembly consists of the following four values:
//
//      Major Version
//      Minor Version
//      Build Number
//      Revision
//
// You can specify all the values or you can default the Revision and Build Numbers
// by using the '*' as shown below:
// [assembly: AssemblyVersion("1.0.*")]
[assembly: AssemblyVersion("{YYYY}.{MM}.{DD}.0")]
[assembly: AssemblyFileVersion("{YYYY}.{MM}.{DD}.0")]

The following values are currently supported:

• {YYYY} – the year
• {MM} – the month
• {DD} – the day
• {SVN} – SubVersion revision number (more on this a bit later)

5. Now, open up the Project Properties > Build Events, and add the following Pre-build event command line (on a single line):

"C:\Path\To\wtv.exe"
  "$(ProjectDir)Properties\AssemblyInfo.Template.cs"
  "$(ProjectDir)Properties\AssemblyInfo.cs"

6. Finally, set the Build Action for the new AssemblyInfo.Template.cs file to ‘None’ and Build!

If you get stuck, pop open a Command Prompt and run WTV.exe without any parameters:

SubVersion support

If you’re using SubVersion for your source control, WTV can also put the projects SVN revision number into the application version.

There’s only one caveat – .Net Application version number values are limited to a maximum of 32,767 (i.e. they’re Int16′s). Therefore, if your SVN revision is higher WTV will only use the last 4 digits: e.g.: 32768 -> 2768.

To use the SVN revision number, simply add the {SVN} placeholder to your AssemblyInfo.Template.cs file like so:

[assembly: AssemblyVersion("{YYYY}.{MM}.{DD}.{SVN}")]
[assembly: AssemblyFileVersion("{YYYY}.{MM}.{DD}.{SVN}")]

.. and then add a couple of extra parameters to the Pre-build event command line so WTV knows where SubWCRev.exe is, something like this (again, on a single line):

"C:\Path\To\WTV.exe"
  "$(ProjectDir)Properties\AssemblyInfo.Template.cs"
  "$(ProjectDir)Properties\AssemblyInfo.cs"
  "C:\Program Files\TortoiseSVN\bin\SubWCRev.exe"
  "$(SolutionDir)."

 
And because the AssemblyInfo.cs is generated, you can remove it from source control (but don’t remove it from your project!)

Finally

Comments and suggestions are welcome here or on the projects issue tracker over at GitHub. I hope you find it useful

While working on an internal ASP.Net MVC project at work, I wondered if it was possible to get the SubVersion (SVN) repository number to be automatically updated on the webpages I was creating every time I did a build or check-in.

The footer at the bottom of the StackOverflow.com site is what we’re trying to do here (though I suspect after listening to their podcasts that they’ve got theirs updated using custom build tasks in CruiseControl.Net)..

After a couple of hours of investigation, trial and error, here’s one way to do it.

Before we begin, we’ll need TortoiseSVN installed, and a local working copy of your ASP.Net MVC project checked out.

There are essentially 3 steps..

1. Create a Html Helper

This greatly simplifies the return of the SVN number as a string which is then trivial to place in our View Page or footer.

Create the following file:

Imports System.Runtime.CompilerServices

Public Module HtmlHelpers

    <extension()> _
    Public Function SVNRevision(ByVal helper As HtmlHelper) As String
        Dim svnFile As IO.StreamReader
        Dim svnRev As String = String.Empty
        Try
            svnFile = New IO.StreamReader("svn_rev.txt")
            svnRev = svnFile.ReadLine()
            svnRev = svnRev.Replace("""", "")
            svnFile.Close()
        Catch FnFex As IO.FileNotFoundException
            'swallow, but write out the file and location we tried to read..
            Trace.WriteLine("HtmlHelper.SVNRevision: Ex: [" & FnFex.Message & "]")
        Finally
            If svnRev.Length = 0 Then svnRev = "-"
        End Try

        Return svnRev
    End Function
End Module

2. Create a Batch File and add it as a custom build task to the project

Next we create a Batch File (.bat) in the root of our project, which will call the TortoiseSVN command to retrieve the SVN revision number from our working copy.
We’ll call it “CreateSvnRevFile.bat”. Here’s the contents:

@echo off
rem # CreateSvnRevFile.bat
rem # Check the Working Copy folder is passed in..
if /I [%1%]==[] goto usage else goto start
:start
rem # (Re)Create the base file so SubWCRev has something to replace
echo "$WCREV$" > svn_rev.txt
rem # Ask SubWCRev to replace with the latest revision
rem #  from the current (working copy) directory
C:\Progra~1\TortoiseSVN\bin\SubWCRev.exe %1 svn_rev.txt svn_rev.txt
rem # Copy the file for local hosting and testing purposes..
copy svn_rev.txt "C:\Program Files\Microsoft Visual Studio 9.0\Common7\IDE" /Y
del svn_rev.txt /Q
goto end

:usage
echo Usage: %0 SvnWorkingCopyDir

:end
rem exit 0

Then we need to add a custom Build Event action to call the Batch File. (The Build Events dialog is in “My Project > Compile > Build Events”)

As shown above, we need to add the line to the “Post-build event command line:” box..

call "$(ProjectDir)CreateSvnRevFile.bat" "$(SolutionDir)\"

3. Add the SVN revision number to our Page

With all of that background plumbing in place, all we need to do now is add a couple of lines of code in the appropriate .aspx file wherever we want our SVN revision number to appear:

  ...
  <%@ import Namespace="MyMvcProject" %>
  ...
  <%=Html.SVNRevision()%>
  ...

the first line imports our Project Namespace (which will obviously depend on your project – you may need to rebuild at this point before the =Html. autocomplete picks up the ‘SVNRevision()’ HtmlHelper).

And we’re done:

So, how does it work?

The Post-build task CreateSvnRevFile.bat does most of the work by creating a temporary text file called svn_rev.txt containing the string “$WCREV$”, and then calls the TortoiseSVN command SubWCRev.exe on the text file to replace the string with the working copy revision number.  It’s worth noting that the revision number is held in the working copy .svn folder so this method doesn’t require a call to your SVN server to work.

The Html Helper code then simply tries to read the updated text file and returns the contents as a string, or it returns a dash (“-”) if there was a problem.

Obviously, if we’re using this on a high-traffic website or frequently referenced page then we’d want to cache the string rather than reading it from the file every time. We could do this by modifying the Html Helper to read the file once into a variable, which we could do by wrapping the actual file reading up in a singleton object, for example.

I hope you find it useful