Transforming web.config

• Make sure the a build option exists for the build you want (Eg. Release, Deployment)
• All xml changes below happen in ProjectName.csproj
• Add Web.Base.Config, by adding
• <Content Include="Web.Base.config">
•     <SubType>Designer</SubType>
•  </Content>
• Make all Configs point to it
• <Content Include="Web.Debug.config">
•      <DependentUpon>Web.Base.config</DependentUpon>
•     </Content>
• Leave the original Web.Config
• <Content Include="Web.config" />  
• Add the transform step
• <Target Name="BeforeBuild">
•   <TransformXml Source="Web.Base.config" Transform="Web.$(Configuration).config" Destination="Web.config" />
• </Target>
• Add Web.Release.Config (for a Release deployment)
• <?xml version="1.0"?>
•   <configuration xmlns:xdt="http://schemas.microsoft.com/XML-Document-Transform">
•     <connectionStrings>
•       <add name="DbConn"  xdt:Transform="Remove" xdt:Locator="Match(name)"/>
•     </connectionStrings>
•   <system.web>
•     <compilation xdt:Transform="RemoveAttributes(debug)" />
•   </system.web>
•  </configuration>

References:

http://stackoverflow.com/questions/10506308/web-config-file-transform-from-command-line

http://www.kongsli.net/nblog/2012/01/13/enabling-web-transforms-when-debugging-asp-net-apps/