Transform appSettings from external file after merge - asp.net-mvc

Question

What I'm trying to do is transform one of appSettings which is in external file:
Here is external.config
<?xml version="1.0"?>
<appSettings>
<add key="SomeKey" value="some value" />
</appSettings>
Web.config
<?xml version="1.0"?>
<configuration>
<appSettings file="..\..\external.config">
<add key="SomeKey1" value="some value 1" />
</appSettings>
</configuration>
Web.Debug.config
<?xml version="1.0"?>
<configuration xmlns:xdt="http://schemas.microsoft.com/XML-Document-Transform">
<appSettings>
<add key="SomeKey" value="some changed value"xdt:Transform="SetAttributes" xdt:Locator="Match(key)"/>
</appSettings>
</configuration>
After build in proper configuration which in my example is Debug there's only this:
<?xml version="1.0"?>
<configuration>
<appSettings file="..\..\external.config">
<add key="SomeKey1" value="some value 1" />
</appSettings>
</configuration>
but it should be:
<?xml version="1.0"?>
<configuration xmlns:xdt="http://schemas.microsoft.com/XML-Document-Transform">
<appSettings>
<add key="SomeKey1" value="some value 1" />
<add key="SomeKey" value="some changed value"/>
</appSettings>
</configuration>
I tryed to make shared appSettings by 2 or more different project 1-st is WCF Service second ASP.NET MVC 4 Application
Edited:
I've tryed to move this file attribute to Web.Debug.config but it's as well doesn't work.
The question is:
How can i accomplish such thing?Is it even possible?

Answer 1

Interesting. I have the same issue like yours. So now here is a workaround for your reference.
Please open project file - XXX.csproj
for example, ISWB.Test.Unit.csproj
add below section like this
<!-- Rock Add here, 2015.03.19 enable the external config transformation -->
<Target Name="BeforeCompile" Condition="Exists('ISWB.$(Configuration).config')">
<!--Generate transformed app config in the intermediate directory-->
<TransformXml Source="ISWB.config" Destination="$(IntermediateOutputPath)ISWB.config" Transform="ISWB.$(Configuration).config" />
<!--Force build process to use the transformed configuration file from now on.-->
<ItemGroup>
<AppConfigWithTargetPath Remove="ISWB.config" />
<AppConfigWithTargetPath Include="$(IntermediateOutputPath)ISWB.config">
<TargetPath>ISWB.config</TargetPath>
</AppConfigWithTargetPath>
</ItemGroup>
</Target>
<Target Name="AfterCompile" Condition="Exists('app.$(Configuration).config')">
<!--Generate transformed app config in the intermediate directory-->
<TransformXml Source="app.config" Destination="$(IntermediateOutputPath)$(TargetFileName).config" Transform="app.$(Configuration).config" />
<!--Force build process to use the transformed configuration file from now on.-->
<ItemGroup>
<AppConfigWithTargetPath Remove="app.config" />
<AppConfigWithTargetPath Include="$(IntermediateOutputPath)$(TargetFileName).config">
<TargetPath>$(TargetFileName).config</TargetPath>
</AppConfigWithTargetPath>
</ItemGroup>
</Target>
Please notice the added section, you have to add it into cs project file in a TEXT editor manually.
Please replace ISWB with yours. And then save it.
it should work well.
Enjoy it!