Thursday, 17 September 2009

Non-Destructive Test Storage Table Creation

For those of you working with Windows Azure Table Storage, I'm sure you're aware of the Create Test Storage Tables feature in Visual Studio:

This function looks through your cloud application for classes derived from DataServiceContext, and then creates matching tables in your local SQL 2008 database.

The frustrating thing is, every time you run Create Test Storage Tables, it blasts away your entire DB, then re-creates it. When you're building a large application, it can be incredibly time consuming to re-instate your test data.


What I'd prefer is if this function synchronised your classes with your current DB, without destroying your data. So I've had a stab at building a replacement program which does just this.

Download Development Storage Sync

Development Storage Sync is an alternative to the standard DevtableGen.exe that ships with the Windows Azure SDK (this is what is executed when you click Create Test Storage Tables. Just like DevtableGen, it looks for classes derived from DataServiceContext in your cloud app. However instead of re-building your DB, it compares each class and property with each table and column to see what's changed, and displays a summary of changes required:

Clicking Sync will then execute the changes, while maintaining any existing data.


After installing the application, you need to tell your cloud app to run DevStorageSync.exe, instead of DevtableGen.exe. To do this, follow these steps:

  1. Open your cloud app project file in a text editor. This is the project file that ends .ccproj.

  2. Locate the following line:
      <Import Project="$(CloudExtensionsDir)Microsoft.CloudService.targets" />
  3. Insert the following directly below this line:
      <Target Name="_CreateDevStorageTable" DependsOnTargets="Build">
            <TableAssemblies Include="%(Roles.Identity)**\*.dll" />
          <Exec Command='"C:\Program Files\DevStorageSync\DevStorageSync.exe" "/config:$(ServiceHostingSDKBinDir)DevtableGen.exe.config" "/database:$(DevTableStorageDatabaseName)" "@(TableAssemblies)"' />
    Note: Ensure the path in the Command attribute points to where you installed DevStorageSync.exe.

What does this do? The Microsoft.CloudService.targets file contains a build target called _CreateDevStorageTable this is the target that is run when you click Create Test Storage Tables (it launches DevtableGen.exe). By adding the same target to your project file, we are overriding the target to point to DevStorageSync.exe

Running DevStorageSync

Just click Create Test Storage Tables as you normally would. You will still get a warning dialog that your existing database will be deleted - just ignore this as this seems to be hard-coded to the menu item in Visual Studio.

Bugs & Feedback

There's sure to be some issues with this, so please report any bugs to me!