Laravel Eloquent and Mysql join a table IF another join is null - php

Question

Three main tables:
products
advertisers
locations
Two pivot tables:
advertisers_locations
products_locations
Relationships:
A product belongs to an advertiser and an advertiser has many locations (Locations it can ship products to)
A product can also have it own set of locations that override the advertiser locations (Some products have delivery restrictions)
What I need to do is:
Select all products
Check if products_locations table for product ID and join it.
If it does not exist then join the advertisers locations table
Is this possible to do in one query and using eloquent? Here's my code - struggling with the conditional:
public function scopeWhereShippableToLocation($query)
{
$location_id = session('location_id');
$query->where(function ($q) use ($location_id) {
$q->join('products_locations', 'products_locations.product_id', '=', 'products.id')
->where('products_locations.location_id', '=', $location_id);
});
$query->orWhere(function ($q) use ($location_id) {
$q->join('advertisers_locations', 'advertisers_locations.advertiser_id', '=', 'products.advertiser_id')
->where('advertisers_locations.location_id', '=', $location_id);
});
//dd($q->toSql());
return $query;
}
This is currently producing a MySQL error:
Column not found: 1054 Unknown column 'products_locations.location_id' in 'where clause' (SQL: select `products`.*,

Answer 1

I think I have a solution for you using eloquent, rather than the query builder. You need to check to see if the relationship exists, if not you need another query. This can be done using the following:
public function scopeWhereShippableToLocation($query)
{
$location_id = session('location_id');
// WhereHas check to see if a relationship exists, IE: The pivot table
// orWhereHas will be checked if the first where does not exist
$query->whereHas('products_locations', function ($q) use ($location_id) {
$q->where('location_id', $location_id);
})->orWhereHas('advertisers_locations', function ($q) use ($location_id) {
$q->where('location_id', $location_id);
});
return $query;
}
This should work providing that your Products, Advertisers and Locations relationship methods are set up.