I have a number of sister models that all extend a base model type. The parent model is Publication; two child models are Book (representing individual books) and Journal (representing individual issues of a periodical). Both books and journal issues can be part of a larger series of publications: journal issues always belong to exactly one periodical, while books may be part of one or more book series (or none at all).
Both models have a relationship called serials(), representing the ‘parent’ series they appear in, but they are different due to the database design (which I can’t change – it’s a live production DB that needs to continue to function with a live system as well):
The journals table has a periodical_id foreign ID to the periodicals table, so the relationship is belongsTo() and returns a single model
The books table relates to the series table through a pivot table, so the relationship is belongsToMany() and returns a collection of models
This means I often need to check if it’s a model or a collection before doing anything. It would be much easier if I could just always assume it’s a collection I can just iterate over whenever I need to do anything with it.
Is there a way in the relationship definition to make sure that even a belongsTo() relationship always returns a collection?
No, there is no way to force a belongsTo() relationship to return a collection. However, you can create a custom accessor method on the Publication model that always returns a collection, even if the relationship is a single model. Here's an example:
class Publication extends Model
{
public function serials()
{
// Define the relationship as usual
return $this->belongsTo(Serial::class);
}
public function getSerialsAttribute()
{
// Always return a collection, even if the relationship is a single model
return collect([$this->serials]);
}
}
With this code, you can always assume that $publication->serials is a collection, even if the relationship is a single model.
