Find item in IList with LINQ

Question

I have an IList:

IList list = CallMyMethodToGetIList();

that I don't know the type I can get it

Type entityType = list[0].GetType();`

I would like to search this list with LINQ something like:

var itemFind = list.SingleOrDefault(MyCondition....);

Thank you for any help.

Solution 1

Simple:

IList list = MyIListMethod();

var item = list
    .Cast<object>()
    .SingleOrDefault(i => i is MyType);

or:

IList list = MyIListMethod();

var item = list
    .Cast<object>()
    .SingleOrDefault(i => i != null);

hope this help!

Solution 2

IList list = ...

// if all items are of given type
IEnumerable<YourType> seq = list.Cast<YourType>().Where(condition);

// if only some of them    
IEnumerable<YourType> seq = list.OfType<YourType>().Where(condition);

Comments

[abatishchev]

OfType<MyType>() will do this for you.

[abatishchev]

basically the are foreach(item) yield return (T)item and foreach(item) if (item is T) yield return item as T respectively.

[Silvermind]

I was under the impression the type was not known at compile time since he used list[0].GetType() to get the type. I agree with your comment at my answer that dynamic is not very efficient, but it supports for Linq.

[Silvermind]

What if the type is a non-nullable value type?

[T-moty]

The filters in .SingleOrDefault(xxx) are ONLY for example. I mean the .Cast<object>() method. ...but your question is interesting! Give me some mins...

[T-moty]

The simplest way, in a generic method, like this: link