如何在LINQ to XML语句中返回同级XElement？

Question

From the following XML input:

<root>
  <node name="one" value="1"/>
  <node name="two" value="2"/>
  <node name="three" value="3"/>
  <node name="four" value="4"/>
</root>";

I need to use LINQ to XML to produce the following:

<root>
  <name content="one"/>
  <value content="1"/>
  <name content="two"/>
  <value content="2"/>
  <name content="three"/>
  <value content="3"/>
  <name content="four"/>
  <value content="4"/>
</root>

This code produces the name elements, but not the value elements.

var input = @"
<root>
  <node name=""one"" value=""1""/>
  <node name=""two"" value=""2""/>
  <node name=""three"" value=""3""/>
  <node name=""four"" value=""4""/>
</root>";


var xml = XElement.Parse(input);
var query = new XElement("root",
    from p in xml.Elements("node")
    select new XElement("name",
        new XAttribute("content", p.Attribute("name").Value) /*,

        new XElement("value", new XAttribute("content", p.Attribute("value").Value)) */
        )
    );

If I include the value XElement (commented out above) inside the last parenthesis then it is a child of the name element, but outside the closing parenthesis it no longer has access to q (it is outside the query).

It feels like I need to concatenate two XElements together or somehow include them in another collection that doesn't produce any XML.

Answer 1

You could flatten the attributes using the Enumerable.SelectMany method . In query format this is equivalent to two from clauses :

var query = new XElement("root",
    from p in xml.Elements("node")
    from a in p.Attributes()
    select new XElement(a.Name,
        new XAttribute("content", a.Value)
        )
    );

To contrast, using the actual SelectMany method and writing it fluently would look like this:

var query = new XElement("root",
        xml.Elements("node")
           .SelectMany(n => n.Attributes())
           .Select(a => new XElement(a.Name,
                new XAttribute("content", a.Value))));

However, I tend to find the query syntax to be clearer in most of SelectMany usages and I tend to stick to one format or another, although it's perfectly fine to mix both.

Answer 2

Using your code as starting point. Wrap the pair in an item element and then replace it with its children.

        var xml = XElement.Parse(input);
        var result = new XElement("root",
            from p in xml.Elements("node")
            select new XElement("item", 
                        new XElement("name", new XAttribute("content", p.Attribute("name").Value)),
                        new XElement("value", new XAttribute("content", p.Attribute("value").Value))));

        result.Descendants("item").ToList().ForEach(n => n.ReplaceWith(n.Elements()));