LINQ Query To Return Duplicates Exclusively

Question

I'm working on this LINQ query. I'd like the resulting list return a list of records that contain duplicates exclusively, based on the EMailAddress1 field and grouped by the EMailAddress1 field.

For instance:

emailaddress1@gmail.com
emailaddress1@gmail.com
emailaddress2@gmail.com
emailaddress2@gmail.com
emailaddress2@gmail.com
emailaddress3@gmail.com
emailaddress3@gmail.com

etc.

Any advice on this? Thanks.

 var contacts = (from c in xrm.ContactSet 
                        where c.StateCode != 1 
                        orderby c.EMailAddress1, c.CreatedOn 
                        descending select new { 
                            c.FirstName, 
                            c.LastName, 
                            c.EMailAddress1, 
                            c.ContactId, 
                            c.CreatedOn }).ToList();

It is neccesary to be a Query? Why not use the native one "find duplicates" — Sxntk, Jul 21 '15 at 21:00
@Sxntk Well I'm doing other things with this list....I suppose I could iterate over each element in the list and compare each other, like this:foreach (var c in contacts) { foreach (var b in contacts) if (b == c) { //Do something } } But what about the grouping? Is there way I can group each "EMailAddress1" field in the list? — user4946742, Jul 21 '15 at 21:33
You can't group with LinQ CRM, you can query all the records on account and with that list use the normal LinQ — Sxntk, Jul 21 '15 at 21:36

score 0 · Accepted Answer · answered Jul 22 '15 at 01:31

Based on your previous query:

var duplicatedEmails = (from c in contacts
                        group c by c.EMailAddress1 into g
                        where g.Count() > 1
                        select g.Key).ToList();
var duplicatedContacts = contacts.Where(c => duplicatedEmails.Contains(c.EMailAddress1));

LINQ Query To Return Duplicates Exclusively

1 Answers1