C# LINQ lambda expression with Contains as a method parameter

Question

I am writing a method that gets a lambda expression as a parameter to be used to filter the IList<SomeModel> _collection .

public void DoSomething(SomeModel model)
{
   FilterCollectionUsingPredicate(x => x.Name.Equals(model.Name));
}

private void FilterCollectionUsingPredicate(Func<SomeModel, bool> predicate)
{
   _collection = _collection.Where(predicate).ToList();
}

It works well when the predicate parameter is a simple expression, like x => x.Name.Equals(model.Name) . However, it gets tricky when it has to use some other (local) collection and Contains clause.

public void DoSomething(SomeModel model)
{
   IEnumerable<string> someOtherCollection = model.SomeOtherCollection;
   FilterCollectionUsingPredicate(x => someOtherCollection.Contains(x.Phone));
}

private void FilterCollectionUsingPredicate(Func<SomeModel, bool> predicate)
{
   _collection = _collection.Where(predicate).ToList();
}

Of course, FilterCollectionUsingPredicate method does not see someOtherCollection and therefore, throws an error. Can someone explain how to properly define and use this function to handle such a case?

Answer 1

Well try and create a generic extension instead, Expression should keep track of all other data in the expression. Try and create the predicate as Expression

private void FilterCollectionUsingPredicate(Expression<Func<SomeModel, bool>> predicate)
{
   _collection = _collection.Where(predicate).ToList();
}

It should work.