How to use Linq to set attributes based on counter

Question

Say I have a xml document that looks like this

<foo>
<bar id="9" />
<bar id="4" />
<bar id="3" />
</foo>

I would like to use linq to reset the id's to 0, 1 ,2. What would be the easiest way to do this?

Thanks

Answer 1

XElement xml = GetXml();
var i = 0;
foreach (var e in xml.Elements("bar"))
  e.SetAttributeValue("id", i++);

Answer 2

I was hoping for a nice 1 liner. Maybe that only exists in my linq dreams.

Answer 3

You can do it with linq methods instead of foreach, but there isn't much bang for the buck:

XElement xml = GetXml();
int updatedElements = xml.Elements("bar")
    .Select((x, i) =>
    {
        x.SetAttributeValue("id", i);
        return x;
    })
    .Count();

Here, the Count() method is necessary to enumerate the query. Anything that enumerates the query would do.

If using the Select as a mutator bothers you (as it does me), use List(T).ForEach instead:

XElement xml = GetXml();
xml.Elements("bar")
    .Select( (x, i) => new {x, i})
    .ToList()
    .ForEach(a => a.x.SetAttributeValue("id", a.i));