How to join relationships in Eloquent? - php

Question

I'm stuck in a problem, I have these 3 models: Order, OrderItem and Product, each Order has many Order Items, and each Order Item has one Prduct but a Product can be ordered several times.
Product has a supplier ID column (each supplier has many Products).
So here are the relationships:
Model: Order:
public function items(){
return $this->hasMany('App\Models\OrderItem','id','order_id');
}
Model OrderItem
public function order(){
return $this->belongsTo('App\Models\Order','order_id','id');
}
public function product(){
return $this->belongsTo('App\Models\Product','item_id','id');
}
Model Product
public function orders()
{
return $this->hasMany('App\Models\OrderItem','item_id','id');
}
What I want is that given a supplier_id, I need to filter Products for that supplier_id, and get the Order Items for that supplier_id and then group them by created date which is only available in the Order Model and not Order Items.
In other words, I want to get all Orders of a given supplier (through the supplier_id column in products) grouped by their creation date but there is no direct relation from Orders to Products I have to get Order Items to get to Products (Orders > Order Items > Products).
I thought about doing the following:
Product::with("orders")->where("supplier_id","=",$supplier_id)->join("orders","orders.id","=","products.orders")
The problem is that products.orders is a relationship (between Product and Order Item) and not a column.

Answer 1

You can do it using DB interface or if you'd like continue using Models you need to use multiple pluck.
You can do something like this:
Product::with(['orders','orders.order'])->where('supplier_id', $supplier_id)->get()->pluck("orders")->flatten()->pluck('order');

Answer 2

Use following snippet:
Product::select(DB::Raw('DATE(created_at) as cr'), ...)->where('supplier_id', $supplier_id)->with('orders.order')->groupBy('supplier_id')->get();
After that, you can loop on the result and group them by date:
$result->groupBy('cr')