How to use XDocument to read csproj files?

Question

I wanted to make some path changes to csproj files to configure for source control. Rather than do it by hand I figured Id iterate over the csproj files and use Linq-to-Xml within each csproj to alter the build and reference paths according to need.

So Ive looked around and am presently trying to use:

public void Read(string  fileName)
{
    XDocument doc = XDocument.Load(fileName);

    foreach (XElement el in doc.Root.Elements())
    {
        Console.WriteLine("{0} {1}", el.Name, el.Attribute("id").Value);
        Console.WriteLine("  Attributes:");
        foreach (XAttribute attr in el.Attributes())
            Console.WriteLine("    {0}", attr);
        Console.WriteLine("  Elements:");

        foreach (XElement element in el.Elements())
            Console.WriteLine("    {0}: {1}", element.Name, element.Value);
    }
}

as per accepted answer of this SO question xml-parsing-read-a-simple-xml-file-and-retrieve-values. However when the line

foreach (XElement el in doc.Root.Elements())

is processed I get a null reference error on the call to Elements. I've also tried calling Nodes, Descendants, etc but they are all null. doc. doc.Root does return everything in the proj file (except the namespace line at the top), so there is something there I'm just not walking it properly.

So what am I doing wrong? I expected Elements to return a collection of XML fragment I could walk or filter to pull out the pieces I want i.e.

Update:

So this is a csproj example:



  
    Debug
    AnyCPU
    8.0.30703
    2.0
    {2CCAB46D-7A7C-4C65-B6D2-DC2D4049FCD9}
    Library
    Properties
    Basd.Core
    Basd.Core
    v4.0
    512
    
    
  
  
    true
    full
    false
    ..\..\Basd.Bin\AnyCPU\Release\
    DEBUG;TRACE
    prompt
    4
    AnyCPU
    false
  
  
    pdbonly
    true
    ..\..\Basd.Bin\AnyCPU\Release\
    TRACE
    prompt
    4
    AnyCPU
    false
  
  
    x86
    ..\..\Basd.Bin\x86\Debug\
    full
    false
  
  
    AnyCPU
    ..\..\Basd.Bin\AnyCPU\Release\
    
    
    pdbonly
    true
    false
  
  
    
    
    
    
    
    
    
    
    
  
  
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
      Code
    
    
    
    
    
    
    
    
    
    
    
      True
      True
      Resources.resx
    
    
    
  
  
    
  
  
    
      ResXFileCodeGenerator
      Resources.Designer.cs

From Intermediate Window with breakpoint set on

 foreach (XElement el in doc.Root.Elements())

?doc.Root.ToString(); "
  
    Debug
    AnyCPU
    8.0.30703
    2.0
    {2CCAB46D-7A7C-4C65-B6D2-DC2D4049FCD9}
  Library
    Properties
    Basd.Core
    Basd.Core
    v4.0
    512
    
  
  
    true
    full
    false
    ..\..\Basd.Bin\AnyCPU\Release\
    DEBUG;TRACE
    prompt
    4
    AnyCPU
    false
  
  
    pdbonly
    true
    ..\..\Basd.Bin\AnyCPU\Release\
    TRACE
    prompt
    4
    AnyCPU
    false
  
  
    x86
    ..\..\Basd.Bin\x86\Debug\
    full
    fals e
  
  
    AnyCPU
    ..\..\Basd.Bin\AnyCPU\Release\
    
    pdbonly
    true
    false
  
  
    
 
    
    
    
    
    
    
    
  
  
    
    
    
    
    
    
    
    
    
 
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
      Code
    
    
    
    
    
    
    
    
    
    
    
      True
      True
     Resources.resx
    
    
    
  
  
    
  
  
    
      ResXFileCodeGenerator
      Resources.Designer.cs
    
  
  
  
" 

?doc.Root.Name; {{http://schemas.microsoft.com/developer/msbuild/2003}Project}
        hashCode: 541551665
        localName: "Project"
        LocalName: "Project"
        Namespace: {http://schemas.microsoft.com/developer/msbuild/2003}
        NamespaceName: "http://schemas.microsoft.com/developer/msbuild/2003"
        ns: {http://schemas.microsoft.com/developer/msbuild/2003} 


?doc.Root.Descendants(); {System.Xml.Linq.XContainer.GetDescendants}
        name: null
        self: false
        System.Collections.Generic.IEnumerator.Current: null
        System.Collections.IEnumerator.Current: null ?doc.Root.Nodes(); {System.Xml.Linq.XContainer.Nodes}
        System.Collections.Generic.IEnumerator.Current: null
        System.Collections.IEnumerator.Current: null ?doc.Root.Attributes();

Kirill Polishchuk · Accepted Answer

You're getting exception in this line:

Console.WriteLine("{0} {1}", el.Name, el.Attribute("id").Value);

because at least first child element of the root, in your sample it is PropertyGroup doesn't contain id attribute.

I can suugest you rewrite this line as

Console.WriteLine("{0} {1}", el.Name, (string)el.Attribute("id"));

In this case your code won't throw any exception.

How to use XDocument to read csproj files?

Answers (1)

Related Questions