How can I use MSBuild 'afterbuild' tasks to edit a .config file?

Question

I have a .config in a target project and I need to add a line to it programmatically via an MSBuild task.

Pseduo operations like:

• find target .config file
• determine the value of attributes for new node (e.g. 'id' and 'version' for 'package' node)
• insert new node in correct parent node
• save changes

The .config file at $TargetProjectDir\Config\packages.config:

<?xml version="1.0" encoding="utf-8"?>
<packages>
  <package id="ABC" version="1.1.0.4" />
  <package id="XYZ" version="2.0.0.0" />
</packages>

Needs to look like this afterwards:

<?xml version="1.0" encoding="utf-8"?>
<packages>
  <package id="ABC" version="1.1.0.4" />
  <package id="XYZ" version="2.0.0.0" />
  <package id="CarDataWidget" version="3.0.0.0" />
</packages>

So far i've considered using 'inline tasks', the 'EXEC' task and 'XmlPoke' task but haven't managed to get any of them working.

Here is my attempt with XmlPoke and XmlPeek:

I used the following article as an inspiration on how to add nodes to the packages.config file: http://weblogs.asp.net/bsimser/appending-nodes-in-xml-files-with-xmlpeek-and-xmlpoke-using-nant

  <Target Name="AfterBuild" DependsOnTargets="AddPackage">
  </Target>
  <Target Name="AddPackage">
    <!-- Load existing nodes into a Property -->
    <XmlPeek XmlInputPath="config/packages.config" Query="/packages/package" >
      <Output TaskParameter="Result" PropertyName="Peeked" />
    </XmlPeek>
    <Message Text="From Peek: $(Peeked)"></Message>

    <!-- Load new node into Property -->
    <PropertyGroup>
      <WidgetName>CarDataWidget</WidgetName>
      <WidgetVersion>2.0.0.0</WidgetVersion>
      <NewNode>&lt;package id&#61;&quot;$(WidgetName)&quot; version&#61;&quot;$(WidgetVersion)&quot; /&gt;</NewNode>

    <!-- Concatenate existing and new node into a Property -->
      <ConcatenatedNodes>$(Peeked)$(NewNode)</ConcatenatedNodes>
    </PropertyGroup>
    <Message Text="New pacakges: $(ConcatenatedNodes)"></Message>

    <!-- Replace existing nodes with concatenated nodes -->
    <XmlPoke Value="$(ConcatenatedNodes)" XmlInputPath="config/packages.config" Query="/packages">
    </XmlPoke>
  </Target>

The output from the above build is:

1>AddPackage:
1>  From Peek: <package id="ABC" version="1.1.0.4" />;<package id="XYZ" version="2.0.0.0" />
1>  New pacakges: <package id="ABC" version="1.1.0.4" />;<package id="XYZ" version="2.0.0.0" /><package id="CarDataWidget" version="2.0.0.0" />
1>  C:\_dev\CarDataWidget.csproj(184,14): 
    error MSB4094: "<package id="ABC" version="1.1.0.4" />;<package id="XYZ" version="2.0.0.0" /><package id="CarDataWidget" version="2.0.0.0" />" 
    is an invalid value for the "Value" parameter of the "XmlPoke" task. 
    Multiple items cannot be passed into a parameter of type "Microsoft.Build.Framework.ITaskItem".
1>
1>Build FAILED.

THE QUESTION: How can get it to add to a .config file with existing package nodes???

Answer 1

I had the same problem. I found the solution here.

The problem is than XmlPoke considers semicolon as a value separator.

Should replace this:

<NewNode>&lt;package id&#61;&quot;$(WidgetName)&quot; version&#61;&quot;$(WidgetVersion)&quot; /&gt;</NewNode>

With:

<NewNode>&lt%3Bpackage id&#61%3B&quot%3B$(WidgetName)&quot%3B version&#61%3&quot%3$(WidgetVersion)&quot%3 /&gt%3</NewNode>

Must replace each semicolon by the secuence %3B

Answer 2

Here is a way to do it using MSBuild Extension Pack.

Set the packages and versions in the NewPackage item group and it adds them to the XML file.

<Project 
    ToolsVersion="4.0" 
    xmlns="http://schemas.microsoft.com/developer/msbuild/2003">

  <Import Project="$(MSBuildExtensionsPath)\ExtensionPack\4.0\MSBuild.ExtensionPack.tasks" />

  <Target Name="Test" DependsOnTargets="AddPackage">
  </Target>

  <ItemGroup>
    <NewPackage Include="CarDataWidget">
        <Version>3.0.0.0</Version>
    </NewPackage>
    <NewPackage Include="FooBarWidget">
        <Version>1.2.3.4</Version>
    </NewPackage>
  </ItemGroup>

  <Target Name="AddPackage">

    <PropertyGroup>
        <InputFile>in.xml</InputFile>
        <OutputFile>out.xml</OutputFile>
    </PropertyGroup>

    <Copy SourceFiles="$(InputFile)" DestinationFiles="$(OutputFile)" />

    <MSBuild.ExtensionPack.Xml.XmlFile
      TaskAction="AddElement"
      File="$(OutputFile)"
      XPath="//packages"
      Element="package"
      Key="id"
      Value="%(NewPackage.Identity)" />

    <MSBuild.ExtensionPack.Xml.XmlFile
      TaskAction="AddAttribute"
      File="$(OutputFile)"
      XPath="//packages/package[@id='%(NewPackage.Identity)']"
      Key="version"
      Value="%(NewPackage.Version)" />
  </Target>
</Project>