Query Laravel Relationship - laravel

Question

I have 3 Model
In Purchase Model
protected $fillable = [
'name', 'date', 'description', 'active', 'supplier', 'total', 'paid', 'purchase_status', 'payment_status',
];
public function product()
{
return $this->belongsTo(\App\Product::class);
}
public function order()
{
return $this->belongsTo(\App\Order::class);
}
In Order Model
protected $fillable = [
'name', 'quantity', 'unit_cost', 'discount', 'tax', 'sub_total'
];
public function order_items()
{
return $this->belongsTo(\App\OrderItem::class);
}
In my OrderItem Model
protected $fillable = ['active', 'description', 'quantity', 'discount', 'unit_price'];
public function order()
{
return $this->belongsTo(\App\Order::class);
}
Is it possible to query Order_Items From Purchases trough Orders Relationship in Laravel?

Answer 1

Oh, i found my answer...
In Order Model
i changed belongsTo to hasMany
protected $fillable = [
'name', 'quantity', 'unit_cost', 'discount', 'tax', 'sub_total'
];
public function order_items()
{
return $this->hasMany(\App\OrderItem::class);
}

Answer 2

Yes you can write this relations in your models and write the query like this:
Purchase
public function order()
{
return $this->belongsTo('App\Models\Order', 'order_id', 'id');
}
Order_Item
public function order()
{
return $this->belongsTo('App\Models\Order', 'order_id', 'id');
}
Order
public function order_items()
{
return $this->hasMany('App\Models\OrderItem', 'order_id', 'id');
}
public function purchases()
{
return $this->hasMany('App\Models\purchase', 'order_id', 'id');
}
Now you can use this query:
$purchase = \App\Models\Purchase::first();
$order_items = $purchase->order->order_items;

Answer 3

I see that you've fixed the relationship Order -> OrderItem of belongsTo to hasMany. But the question was also about how to query through relationships so I'll just add up to this so it could be useful to other users here.
Now you could do
$order_items = $purchase->order->order_items
to get the order items of the purchase.
However you should consider that this would execute further queries to the DB. One for fetching the order and then another one for fetching the order_items. If you're looping through a list of purchases, this could escalate quickly and end up making too much DB queries and affect the performance of your application.
The solution is eager loading.
You could do either pre-fetch the order and items along with the purchase like this:
$purchase = Purchase::with('order.order_items')->find(1);
or if you've already fetched the purchase, then you could do:
$purchase->load('order.order_items');
Then when getting the order items in your code like this
$purchase->order->order_items, you have no additional queries to the DB.