Laravel Eloquent to join table and count related - sql

Question

How do I use join with Eloquent taking in consideration the following table structure:
I have a properies table
---------------------
ID | Name
---------------------
1 | Property Name
than I have rooms
----------------------
RoomID | Property
----------------------
A-212 | 1
----------------------
F-1231 | 1
here Property is the foreign key
than I want to get all Properties and count how many rooms do they have each
The query which retrives all looks like
class PropertiesRepository extends EloquentBaseRepository implements PropertiesInterface
{
use TaggableRepository;
/**
* Construct
* #param Properties $properties
*/
public function __construct( Properties $properties )
{
$this->model = $properties;
}
/**
* Get all properties joining rooms
* #return Properties
*/
public function getAll()
{
return $this->model->get();
}
}
How do I extend this query to get the desired result?

Answer 1

This is more of a MySQL join+group+select trick which includes following steps.
Join your relation table(use join if you want to exclude rows with RoomsCount=0, else use leftJoin)
Use groupBy by primaryKey to avoid duplicates of the join.
Select count of joined table
$this->model->leftJoin('Rooms', 'Properties.ID', '=', 'Rooms.Property')
->selectRaw('Properties.*, count(Rooms.RoomID) as RoomsCount')
->groupBy('Properties.ID')
->get();

Answer 2

Define the relationship on your Property model class:
<?php
namespace App\Models;
class Property extends Model {
public function rooms() {
return $this->hasMany(Room::class);
}
}
$properties = Property::withCount(['rooms'])->get();
This will add a rooms_count to the result.