Linq to compare two lists of objects where one object has several lists

c#, linq

Solution

It sounds like you want a join:

var query = from x1 in list1
            join x2 in list2 on x1.g2 equals x2.g4
            select x1;

Or in extension method syntax:

var query = list1.Join(list2, x1 => x1.g2, x2 => x2.g4, (x1, x2) => x1);

Note that this will only give you the items from `list1` - if you need the corresponding item from `list2` as well, that's simple:

var query = from x1 in list1
            join x2 in list2 on x1.g2 equals x2.g4
            select new { x1, x2 };

Problem

``` public class MyObject1 { public Guid g1; public Guid g2; public Guid g3; } public class MyObject2 { public Guid g4; } List<MyObject1> list1; List<MyObject2> list2; ``` I would like a LINQ query that would return all MyObject1 objects in list1 where MyObject1.g2 == MyObject2.g4 where the MyObject2 objects live in list 2 i have written code that does this in numerous steps but i would think i could do it in one iteration. so something like ``` var n = list1.Select(p=> p.g2).ToList() var o = list2.Intersect(n) ``` but now i need to research list1 using o again which is awkward

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