Help with Query in Linq C #

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Help with Query in Linq C #

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#1 by (1 votes)

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I have a message table in the following scheme:

Id | osID |Interessado | Remetente | Destinatario | Msg
--------------------------------------------------
1  |  2   |João        |   João    |   Maria      |bla bla bla...
2  |  2   |João        |   Maria   |   João       |ble ble ble...
3  |  3   |Erik        |   Erik    |   Mark       |O Amadeu ganhou a promoção...
4  |  3   |Erik        |   Mark    |   Erik       |Eu sabia...
5  |  3   |Erik        |   Mark    |   Erik       |Vou pedir as contas...
6  |  4   |Jake        |   Jake    |   Mara       |As oito da noite lá em casa...

The scenario I need is for every logged-in user to upload their conversations, so I have the following query:

var mensagens = from p in db.Chats
                            orderby p.Id descending
                            where p.Remetente == MinhaPessoa.Usuario || p.Destinatario == MinhaPessoa.Usuario
                            select p;

This query returns all records if I am the sender or recipient. Now, how do I group this by Service Order (osID) and Interested, and that the last message is displayed?

asp.net linq group-by

asked by anonymous 30.10.2018 / 17:51

1 answer

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score 1 · Answer 1

With the help of @Lucas Miranda I was able to implement the following:

var msg = from p in db.Chats 
orderby p.ChatId descending 
group p by new { p.ContaId, p.InteressadoId } 
into g select new { Interessado = g.Key, Conta = g.Select(m => m.ChatId).First() };

Instead of selecting fields, I take the primary key and the other implement fields through it