Laravel eloquent querying with multiple relationships - php

Question

I have four tables which is departments, users, items, items_inventories
The relationship is like this:
A user has a assigned department.
An item has a assigned department. item_inventories has many items.
Structure:
users
->id
->name
->password
->access_type (department_id)
departments
->id
->name
items
->id
->name
->department_id
items_inventories
->id
->item_id
->qty
My models:
class Item extends Model
{
public function department()
{
return $this->hasOne('App\Http\Models\Department', "id", "department_id");
}
}
class ItemsInventory extends Model
{
public function item()
{
return $this->hasOne('App\Http\Models\Item', "id", "item_id");
}
}
In my items_inventories how do I query all items that belongs to a specific department? Since items has already a relationship to departments, How do I query like: select all items in items_inventories where item department_id is equal to 3?
My goal is, I have a user who is logged in, and I can access the assigned department to him/her via access_type (department_id) when my page loads, I want to list only items in the items_inventories that is assigned to his/her department. I already checked: https://laravel.com/docs/5.4/eloquent-relationships#relationship-methods-vs-dynamic-properties but can't seem to find something that matches my requirement. Thanks

Answer 1

Your relationships are a bit confusing. The table structure says that items belong to departments and item inventories belong to items. I've based the relationship on your table structure and how you can achieve your desired result. You might want to check on your relationship once more to verify how exactly you want it to pan out. As for the current relationship, my models should give you an idea.
class User extends Model
{
public function department()
{
return $this->belongsTo('App\Http\Models\Department', 'access_type');
}
}
class Department extends Model
{
public function items()
{
return $this->hasMany('App\Http\Models\Item');
}
public function itemInventory()
{
return $this->hasManyThrough('App\Http\Models\ItemsInventory', 'App\Http\Models\Item');
}
}
class Item extends Model
{
public function department()
{
return $this->belongsTo('App\Http\Models\Department');
}
public function itemInventory()
{
return $this->hasMany('App\Http\Models\ItemsInventory');
}
}
class ItemsInventory extends Model
{
public function item()
{
return $this->belongsTo('App\Http\Models\Item');
}
}
Controller logic
$department_id = 3;
$itemInventory = ItemsInventory::whereHas('item', function ($query) use ($department_id) {
$query->where('department_id', $department_id);
})->get();
// With user:department relation and department:iteminventory 'hasManyThrough' relation.
$itemInventory = $user->department()->itemInventory;