在匿名类型集合上使用Contains（）

Question

I'm still learning LINQ and I have a collection of anonymous types obtained using something like the following. [mycontext] is a placeholder for my actual data source:

var items = from item in [mycontext]
            select new { item.col1, item.col2, item.col3 };

How can I use items.Contains() to determine if items contains a matching value?

The value I am searching for is not an anonymous type. So I will need to write my own compare logic, preferably as a lambda expression.

Answer 1

If you prefer to use a predicate then you're probably better off using Any rather than Contains :

bool exists = items.Any(x => x.col1 == "foo"
                             && x.col2 == "bar"
                             && x.col3 == 42);

Answer 2

Try the LINQ Any() method:

if (items.Any(i => i.col1 == myOtherThing.Value))
{
    // Effectively Contains() == true
}

Answer 3

或者您可以将“Any”方法与谓词一起使用。

bool exists = items.Any( i => {logic} );