php - Order By before Group By using Eloquent (Laravel)

Question

I have a "messages" table with the following columns

CREATE TABLE `messages` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `fromId` int(11) NOT NULL,
  `toId` int(11) NOT NULL,
  `message` text NOT NULL,
  `status` int(11) NOT NULL,
  `device` varchar(100) NOT NULL,
  `createdAt` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=57 DEFAULT CHARSET=latin1;

I'm trying to get all messages where 'toId' = $id and grouping by fromId. The problem is that the "message" shown on the results is the first ones, not the latest ones. I tried ordering by createdAt but it's not working.

How can I order by "createdAt" prior to querying and grouping the results? I want to do this in the laravel way using Eloquent.

My query:

$chats = Message::with('sender','recipient')
        ->where('toId',$id)
        ->orderBy('createdAt')
        ->groupBy('fromId')
        ->paginate(10)

Answer 1

I just needed to do something similar with a messages model. What worked for me was applying the unique method on the returned eloquent collection.

Model::where('toId', $id)
    ->orderBy('createdAt', 'desc')
    ->get()
    ->unique('fromId');

The query will return all messages ordered by createdAt and the unique method will reduce it down to one message for each fromId. This is obviously not as performant as using the database directly, but in my case I have further restrictions on the query.

Also, there are many more useful methods for working with these collections: https://laravel.com/docs/5.2/collections#available-methods