How to take elements from the same collection based on other atrributes-CodePudding

Hi I have a collection of objects:

MyClasss{
int Id,
int ?OtherId
}

I want to take do sth like:

collection.Where(x.Id == y.OtherId).

Ho to perform it in linq?

CodePudding user response：

I think you're looking for:

collection.Where(x => collection.Any(y => x.Id == y.OtherId));

Be aware that this will also pull out ones where the OtherId is equal to the Id on the same object.

CodePudding user response：

I think your problem is that Id is an int, while OtherId is a nullable int.

You have a sequence of objects of MyClass, and you want to keep only those objects where "Id equals OtherId". Or to be precise:

Keep only those objects where OtherId is not null, and OtherId == Id.

The easiest method would be:

IEnumerable<MyClass> myCollection = ...

IEnumerable<MyClass> result = myCollection
    .Where(myClass => myClass.OtherId.HasValue && myClass.Value == myClass.Id);