[question] Using inverse ActiveRecord associations to avoid N+1 queries? about graphql-batch

[dylanahsmith]

One of the advantages of AssociationLoader in the examples is that it actually loads the association. Your example seems more like the RecordLoader example, which could more naturally be extended to support of the active record query interface (e.g. joins or named scopes).

The danger of doing too much in the way of filtering in the query is that it could result in multiple queries being performed on the same data in the database, where it could be more appropriate to do the additional filtering client-side to avoid doing an extra query.

We use a separate loader for calculations (i.e. aggregations), which is something we could probably add an example. I don't think it makes sense to combine that with the RecordLoader to make it more complicated by adding the internally divergent code path.

      # Make sure all loaded records are authorized 
      # (either with simple scopes on models or using a library like Pundit).
      scope = target_class.authorized_scope_for(@user)

This makes the example less general and adds an additional dependency for the example that makes it harder to use. I would prefer to leave this sort of customization to the library user.

Do you load more complex associations using something similar or do you implement a loader per every association?

Custom loaders have the advantage of adding a layer of abstraction, which can be useful to decouple the code using the loader from the underlying implementation when it is expected to change. When an abstraction isn't needed, then re-using more general associations makes sense.

[martinliptak]

@dylanahsmith Thank you for your extensive answer!

[fedefa]

Hi @dylanahsmith @martinliptak ! Thank you for your explanation. Can you explain me why loading the association using the preloader has any advantage?

One of the advantages of AssociationLoader in the examples is that it actually loads the association

From my point of view, the only important thing is to calculate the value and populate the <key,value> store. Also, using the preloader, record.association_name will be called only from the perform action.