Query JSON and Array ID Columns with Array-Column Relationships

Define relationships on models where foreign keys are stored as JSON arrays or comma-separated lists rather than traditional single-id foreign keys.

When dealing with legacy schemas or denormalized database designs where a model stores multiple related IDs inside a JSON array column (e.g. `[1, 2, 5]`), standard Eloquent relationships fail.

Using array column relationship packages or custom query scope join helpers allows seamless querying:

use App\Models\Tag;
use Illuminate\Database\Eloquent\Model;

class Product extends Model
{
    protected $casts = [
        'tag_ids' => 'array',
    ];

    // Query products that contain specific tag IDs inside JSON array
    public function scopeWithTag($query, int $tagId)
    {
        return $query->whereJsonContains('tag_ids', $tagId);
    }
}

// Fetch products matching tag array
$products = Product::withTag(5)->get();

• Enables relational queries on denormalized JSON array fields
• Uses database-native whereJsonContains() for optimized index searching
• Ideal for tag lists, permission arrays, and multi-category selections