How to read configuration that contains a "Name" attribute using Microsoft.Extensions.Configuration

Question

I am trying to read a configuration in my application.

Consider the code below...I load an XML in memory and it contains 3 different nodes. I can only get the value of the node with no Name attribute

      const string content = @"<?xml version=""1.0"" encoding=""utf-8""?>
<configuration>
  <node1 Name=""something"" Foo=""Bar"" />
  <node2 NoName=""something"" Foo=""Bar"" />
  <node3 Name=""ignored"" NoName=""something"" Foo=""Bar"" />
</configuration>";
      var doc = new XmlDocument();
      doc.LoadXml(content);
      using var stream = new MemoryStream();
      doc.Save(stream);
      stream.Position = 0;
      var configurationRoot = new ConfigurationBuilder()
        .AddXmlStream(stream)
        .Build();

      var node1 = configurationRoot.GetSection("node1").Get<Node1>();
      var node2 = configurationRoot.GetSection("node2").Get<Node2>();
      var node3 = configurationRoot.GetSection("node3").Get<Node2>();

And the Node classes

    private class Node1
    {
      public string Name { get; set; }
      public string Foo { get; set; }
    }

    private class Node2
    {
      public string NoName { get; set; }
      public string Foo { get; set; }
    }

The configuration has 3 nodes, node1 contains the attribute Name and I am trying to read it using Node1

configurationRoot.GetSection("node1").Get<Node1>() does not populate the values.

node2 does not contain the attribute Name and I am trying to read it using Node2

configurationRoot.GetSection("node2").Get<Node2>() populate the values as expected.

Finally, node3 does contain the attribute Name but I am trying to read it using Node2, (that does not care about the name).

configurationRoot.GetSection("node3").Get<Node2>() also does not populate any of the values.

How can I read a node that contains a Name attribute.

Answer 1

The source code on GitHub shows that the Name attribute gets a special treatment.

// The special attribute "Name" only contributes to prefix
// This method retrieves the Name of the element, if the attribute is present

In short, the value of the name attribute is being included in the (section/item) key.

To retrieve node1 you need to call

var node1 = configurationRoot.GetSection("node1:something").Get<Node1>();

For node3 that is

var node3 = configurationRoot.GetSection("node3:ignored").Get<Node2>();

---

The debug visualizer in Visual Studio for configurationRoot shows these keys.

---

The documentation explains the concept of this Name attribute and shows some examples about when and how to use.

In .NET 5 and earlier versions, add the name attribute to distinguish repeating elements that use the same element name. In .NET 6 and later versions, the XML configuration provider automatically indexes repeating elements.