Linq to update a collection with values from another collection?

Question

I have IQueryable baseList

and List someData

What I want to do is update attributes in some

Answer 1

You can't simply find objects that are in one list but not the other, because they are two different types. I'll assume you're comparing a property called OtherProperty that is common to the two different classes, and shares the same type. In that case, using nothing but Linq queries:

// update those items that match by creating a new item with an
// updated property
var updated =
    from d in data
    join b in baseList on d.OtherProperty equals b.OtherProperty
    select new MyType()
    {
        PropertyToUpdate = d.PropertyToUpdate,
        OtherProperty = d.OtherProperty
    };

// and now add to that all the items in baseList that weren't found in data
var result =
    (from b in baseList
     where !updated.Select(x => x.OtherProperty).Contains(b.OtherProperty)
     select b).Concat(updated);