Laravel: Count number of rows in a relationship - php

Question

I have the following relationship:
A venue has many offers
A offer has many orders
I have the following Eloquent model to represent this:
class Venue {
public function orders()
{
return $this->hasManyThrough(Order::class, Offer::class);
}
}
I want to determine the total number of orders for venues with location_id = 5 using Laravel's Eloquent model.
The only way I managed to do this is as follows:
$venues = Venue::where('location_id', 5)->with('orders')->get();
$numberOfOrders = 0;
foreach($venues as $venue) {
$numberOfOrders += $venue->orders->count();
}
dump($numberOfOrders); // Output a single number (e.g. 512)
However, this is obviously not very efficient as I am calculating the count using PHP instead of SQL.
How can I do this using Eloquent model alone.

Answer 1

You can use Eloquent. As of Laravel 5.3 there is withCount().
In your case you will have
$venues = Venue::where('location_id', 5)->with('orders')->withCount('orders')->get();
Then access it this way
foreach ($venues as $venue) {
echo $venue->orders_count;
}
Can find reference here: https://laravel.com/docs/5.3/eloquent-relationships#querying-relations

Answer 2

$venues = Venue::with([
'orders' => function ($q) {
$q->withCount('orders');
}
])->get();
then use it this way for getting single record
$venues->first()->orders->orders_count();
Alternatively, you can use this way too for collections
foreach($venues as $venue)
{
echo $venue->order_count;
}

Answer 3

If you are using Laravel 5.3 or above you can use withCount.
If you want to count the number of results from a relationship without
actually loading them you may use the withCount method, which will
place a {relation}_count column on your resulting models. For example:
$venues = Venue::withCount(['orders'])->get;
foreach ($venues as $venue) {
echo $venue->orders_count;
}
You can read more about withCount in the Laravel Documentation.
If you are using lower than 5.3, you can make a custom relation on your Venue model:
public function ordersCount()
{
return $this->belongsToMany('App\Models\Order')
->selectRaw('venue_id, count(*) as aggregate_orders')
->groupBy('venue_id');
}
public function getOrderCount()
{
// if relation is not loaded already, let's do it first
if (!array_key_exists('ordersCount', $this->relations)) {
$this->load('ordersCount');
}
$related = $this->getRelation('ordersCount')->first();
// then return the count directly
return ($related) ? (int) $related->aggregate_orders : 0;
}
which can then be used as: Venue::with('ordersCount');. The benefit of this custom relation is you only are querying the count rather than the querying all of those relations when they are not necessary.