I was chatting with a co-worker about using LINQ to replace for-each loops. More specifically, we were discussing how to modify the properties of items in a collection or a subset of the collection. I didn’t know how to do it immediately, but I worked on it a bit and found a pretty cool way to do just that.
My first thought was that you could just put your logic into a Select method, modify the objects, and then return a dummy value that would be ignored. Something like this:
// this does not work!
values.Select(x =>
{
x.Name = x.Name.ToUpper();
return true;
});
This did not work, though! I’m not entirely sure why, but I tried a few different approaches and found a way that does work. It feels less hacky, too, since I’m not returning that meaningless dummy value.
Here’s the solution that I came up with:
values.Aggregate(null as Person, (av, e) =>
{
e.Name = e.Name.ToUpper();
return av ?? e;
});
If you only want to manipulate a subset of the collection, you can insert a Where method before your aggregate, like this:
values.Where(x => x.Name.Equals("Blah"))
.Aggregate(null as Person, (av, e) =>
{
e.Name = e.Name.ToUpper();
return av ?? e;
});
You can read more about the Aggregate method here.
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