In Laravel, both `morphToMany` and `morphedByMany` are used to define many-to-many polymorphic relationships, but they serve different roles in the relationship setup.
morphToMany
- This method is used on the model that owns or initiates the polymorphic many-to-many relationship.
- It defines the relationship from the perspective of the model that is related to multiple other models through a polymorphic pivot table.
- For example, if you have `Post` and `Video` models that can be tagged, in the `Post` and `Video` models you define the `tags()` method using `morphToMany` to get all tags associated with that model.
- It accepts the related model class and the "name" of the polymorphic relation (e.g., `'taggable'`), which corresponds to the morph prefix used in the pivot table columns (`taggable_id` and `taggable_type`).
php
class Post extends Model {
public function tags() {
return $this->morphToMany(Tag::class, 'taggable');
}
}
morphedByMany
- This method is used on the inverse side of the polymorphic many-to-many relationship.
- It defines the relationship from the perspective of the related model that is associated with multiple other models.
- Continuing the example above, in the `Tag` model you define methods like `posts()` and `videos()` using `morphedByMany` to get all posts or videos associated with a given tag.
- It accepts the related model class and the morph name, allowing Laravel to retrieve all models of that type that are related to the current model.
php
class Tag extends Model {
public function posts() {
return $this->morphedByMany(Post::class, 'taggable');
}
public function videos() {
return $this->morphedByMany(Video::class, 'taggable');
}
}
Summary of Differences
- Role in relationship:
- `morphToMany` is defined on the model that "owns" or "has" the polymorphic relation (e.g., `Post` or `Video` having many tags).
- `morphedByMany` is defined on the model that is "related to" or "tagged by" the polymorphic owners (e.g., `Tag` knowing which posts or videos it belongs to).
- Direction:
- `morphToMany` is the forward relation from the polymorphic model to the related model.
- `morphedByMany` is the inverse relation from the related model back to the polymorphic models.
- Typical usage:
- Use `morphToMany` on models like `Post` or `Video` to get their tags.
- Use `morphedByMany` on the `Tag` model to get all posts or videos tagged with it.
This pattern allows Laravel to manage many-to-many polymorphic relationships cleanly with a single pivot table that includes `taggable_id` and `taggable_type` columns, supporting relationships between multiple models and a shared related model like `Tag`[1][3][5][7].
Example Context
- Tables: `posts`, `videos`, `tags`, and a pivot table `taggables` with columns `tag_id`, `taggable_id`, `taggable_type`.
- Models:
- `Post` and `Video` use `morphToMany(Tag::class, 'taggable')` to get tags.
- `Tag` uses `morphedByMany(Post::class, 'taggable')` and `morphedByMany(Video::class, 'taggable')` to get all posts and videos tagged with it.
This setup enables flexible many-to-many polymorphic relationships in Laravel's Eloquent ORM.
Citations:
[1] https://laravel.com/docs/11.x/eloquent-relationships
[2] https://stackoverflow.com/questions/75729230/laravel-polymorphic-relationships-morphto-morphmany-or-regular-relationships
[3] https://www.sitepoint.com/eloquents-polymorphic-relationships-explained/
[4] https://laracasts.com/discuss/channels/eloquent/eloquents-morphedbymany-method
[5] https://blog.logrocket.com/polymorphic-relationships-laravel/
[6] https://stackoverflow.com/questions/43496503/laravel-polymorphic-types-table-vs-many-types-tables
[7] https://laraveldaily.com/post/laravel-polymorphic-many-to-many-get-all-related-records
[8] https://laracasts.com/discuss/channels/laravel/solving-this-polymorphic-many-to-many-relationship
[9] https://simple-code.agency/blog/development/simplifying-many-to-many-relationships-with-laravel-polymorphic-relations