c# linq to xml , find nested element by it's attribute

Question

I have a nested element xml like below

<ExecutionGraph>
  <If uniqKey="1">
    <Do>
      <If uniqKey="6">
        <Do />
        <Else />
      </If>
    </Do>
    <Else>
      <If uniqKey="2">
        <Do />
        <Else>
          <If uniqKey="3">
            <Do />
            <Else />
          </If>
        </Else>
      </If>
    </Else>
  </If>
</ExecutionGraph>

Each If element has uniqKey attribute. Know I want to find uniqKey="3" with linq and add some elements in its tag. it's element.

It's been hours which I'm searching but I didn't find any solution.

Thanks in advance.

Answer 1

To find the element, given:

XDocument doc = XDocument.Parse(@"<ExecutionGraph>
  <If uniqKey=""1"">
    <Do>
      <If uniqKey=""6"">
        <Do />
        <Else />
      </If>
    </Do>
    <Else>
      <If uniqKey=""2"">
        <Do />
        <Else>
          <If uniqKey=""3"">
            <Do />
            <Else />
          </If>
        </Else>
      </If>
    </Else>
  </If>
</ExecutionGraph>");

then, quite easily:

var el = doc.Descendants()
    .Where(x => (string)x.Attribute("uniqKey") == "3")
    .FirstOrDefault();

(Descendants() returns recursively all the elements)

Then to add a new element inside the found element:

var newElement = new XElement("Comment");
el.Add(newElement);

(clearly you should check that el != null!)