Filtered many_to_many Relationships with metadata on join Resource

Hmm…I generally suggest trying to avoid making special actions that load relationships with special filters, because that breaks a lot of things down the line. You can do it on demand pretty easily with things like: load(real: Ash.Query.filter(Related, store_id == ^store_id)), and that is something that is also supported by AshGraphql automatically, i.e you’d be able to do this:

getStore(id: "id"){
  relationship(filter: {....}) {...}
}

Often to solve for this you expose the underlying has_many relationship by defining it yourself and pointing the many_to_many to use it, i.e

has_many :foo_joins, FooJoin do
  ...
end

many_to_many :foo, Foo do
  join_relationship :foo_joins
  ...
end

Then clients can easily filter on join attributes or on destination attributes.

Ultimately, if you decide you want something special here my suggestion would be to go with a calculation that returns instances of a resource. For example:

calculate :stuff_you_want, {:array, :struct}, CalculationModule do
  constraints [items: [instance_of: SomeResource]]
end