DevForce Community Forum : Overriding GetHashCode / Equals of Entity http://www.ideablade.com/forum/ This is an XML content feed of; DevForce Community Forum : DevForce 2012 : Overriding GetHashCode / Equals of Entity Mon, 13 Apr 2026 14:04:14 -700 Tue, 20 Aug 2013 12:58:51 -700 http://blogs.law.harvard.edu/tech/rss Web Wiz Forums 9.69 360 www.ideablade.com/forum/RSS_post_feed.asp?TID=4284 DevForce Community Forum http://www.ideablade.com/forum/forum_images/IdeaBlade_logo_tm.png http://www.ideablade.com/forum/ Overriding GetHashCode / Equals of Entity : I'm not sure I understand... http://www.ideablade.com/forum/forum_posts.asp?TID=4284&PID=16755#16755 Author: kimj
Subject: 4284
Posted: 20-Aug-2013 at 12:58pm

I'm not sure I understand in what situations reference equality wouldn't be appropriate for an entity, unless you're working across EntityManagers.  But anyway, GroupBy accepts an IEqualityComparer, so you could implement a simple comparer which uses the EntityKey to determine equality.]]> Tue, 20 Aug 2013 12:58:51 -700 http://www.ideablade.com/forum/forum_posts.asp?TID=4284&PID=16755#16755 Overriding GetHashCode / Equals of Entity : We have some projections that... http://www.ideablade.com/forum/forum_posts.asp?TID=4284&PID=16754#16754 Author: smi-dan
Subject: 4284
Posted: 20-Aug-2013 at 10:11am

We have some projections that return an entity as a property. When grouping on those properties, despite the entity being the same, it will group based on reference and so we end up with two groups for what is the same entity. 

As a solution I've overridden GetHashCode and Equals on the entity with;

        public override int GetHashCode()
        {
            return DealerId == 0 ? base.GetHashCode() : DealerId.GetHashCode();
        }

        public override bool Equals(object obj)
        {
            var x = obj as Dealer;
            if (x == null) 
                return false;

            if (DealerId == 0 && x.DealerId == 0) 
                return ReferenceEquals(this, x);

            return DealerId == x.DealerId;
        }

Which works fine, however, is there another solution? As this solution would require I override these methods for all entities in my model.


Edited by smi-dan - 20-Aug-2013 at 10:13am]]> Tue, 20 Aug 2013 10:11:27 -700 http://www.ideablade.com/forum/forum_posts.asp?TID=4284&PID=16754#16754