Linq Xml - Find attributes by value

Question

If I have a simple XML document such as

<case id="37d3c93c-3201-4002-b24f-08e1221c3cb7">
    <party id="26dad8c5-9487-48f2-8911-1d78c00095b2">...</party>
    <illustration CaseId="37d3c93c-3201-4002-b24f-08e1221c3cb7">....</illustration>
    <illustration CaseId="37d3c93c-3201-4002-b24f-08e1221c3cb7">....</illustration>
    <item relatedCaseId="37d3c93c-3201-4002-b24f-08e1221c3cb7">...</illustration>
</case>

I have code that changes the id attribute of the case element. I am now looking for some LINQ code that would help me search all elements that have an attribute value that matches the old value so I can replace it with the new value. I do not have a list of attribute names, and would need to search the entire document.

Any tips/ideas? Thanks!

Answer 1

Something like this:

var matches = doc.Descendants()
                 .Where(x => x.Attributes()
                              .Any(attr => attr.Value == oldValue));

Or if you're just trying to replace the values, you only need the attributes themselves:

var attributes = doc.Descendants()
                    .Attributes()
                    .Where(attr => attr.Value == oldValue)
                    .ToList();
foreach (var attribute in attributes)
{
    attribute.Value = newValue;
}

It's entirely possible that the copy to a list isn't necessary in this case, but I generally prefer to make a copy when mutating an XDocument to avoid confusing things. (It's certainly necessary when you're removing an element or something like that - just setting the value of an attribute probably doesn't affect things.)