Yes, `loadMissing` can be used with nested relationships in Laravel, but there are some nuances to be aware of.
What is `loadMissing`?
The `loadMissing` method in Laravel Eloquent is used to eager load relationships only if they have not already been loaded on the model instance. This helps avoid redundant queries by checking if the relationship data is already present before querying the database again[6].
Using `loadMissing` with Nested Relationships
- You can specify nested relationships in dot notation with `loadMissing`, such as `'author.contacts'`, to load a nested relationship only if it is missing[7].
- However, there is a known behavior where if you `loadMissing` a nested relation of a relation that is already loaded, Laravel may reload the parent relation itself. For example, if you have already loaded `inscriptions` on a model, then calling `loadMissing('inscriptions.nestedRelation')` will cause the `inscriptions` relation to reload entirely[1].
- This means that while `loadMissing` supports nested relations, it can trigger reloading of the intermediate relations if they were previously loaded but without the nested relation.
Practical Considerations
- `loadMissing` is useful when you want to conditionally eager load relationships, preventing duplicate queries if the relation is already loaded.
- For nested relationships, you should be aware that loading a nested relation missing from a previously loaded parent relation may cause the parent relation to reload, which can impact performance.
- If you want to avoid such reloads, you might need to carefully manage when and how you load nested relations or consider eager loading them upfront with `with()`.
Summary
- Yes, `loadMissing` can be used with nested relationships using dot notation.
- It only loads the nested relations if they are missing.
- But if the parent relation is loaded without the nested relation, `loadMissing` may reload the parent relation to fetch the nested data[1][6][7].
This behavior is important to keep in mind to avoid unexpected multiple queries when working with nested eager loading in Laravel.
Citations:
[1] https://github.com/laravel/framework/issues/23027
[2] https://stackoverflow.com/questions/62563063/filtering-a-nested-relation-in-graphql
[3] https://compositecode.blog/2023/07/25/graphql-nested-queries-relationships-practices/
[4] https://github.com/fifemon/graphql-datasource/issues/15
[5] https://www.sea-ql.org/sea-orm-cookbook/001-how-to-load-nested-relation.html
[6] https://stackoverflow.com/questions/47238937/laravel-what-is-the-purpose-of-the-loadmissing-function
[7] https://stackoverflow.com/questions/35490728/laravel-eloquent-eager-loading-of-multiple-nested-relationships/53205641
[8] https://docs.sqlalchemy.org/14/orm/loading_relationships.html
[9] https://www.prisma.io/docs/orm/prisma-client/queries/relation-queries