Block syntax for associations.

[beauby]

This PR is half of #1262, introducing the block syntax for overriding associations (and removing the legacy method defining syntax).

Currently 2 tests fail, I believe those tests are ill (they seem to expect an association to be treated as an attribute).

[NullVoxPopuli]

why was this a try before?

[beauby]

Because the self._reflections was not initialized in the constructor.

[NullVoxPopuli]

so any class that inherits Associations must have a _reflections accessor?
can you document that, please?
I know it's outside the scope of a refactor, but since we have next to none of this type of documentation, I think it will be good to do it as we go.

[beauby]

No, including Associations does declare a _reflections accessor.

[beauby]

c.f. https://github.com/rails-api/active_model_serializers/pull/1311/files#diff-b2b037951247cfa436c1f2201f5c12dfL16

[NullVoxPopuli]

oh ok, so you're setting base._reflections just to an empty array?

[beauby]

depending if the parent class has some reflections already or not

[NullVoxPopuli]

I'm confused. Sorry. Can you summarize?

[beauby]

Module Associations defines (on the class that includes it) a class attribute _reflections that is initialized to [] and is inherited.

[beauby]

To be clear, those changes are mainly (if not only) cosmetic, in order to be consistent with how we deal with inheritance of class attributes all around, they're not necessary for this PR.

[NullVoxPopuli]

what is a reflection?

[beauby]

https://github.com/rails-api/active_model_serializers/blob/master/lib/active_model/serializer/reflection.rb

[NullVoxPopuli]

oh. ha. didn't see there was more. thanks

[beauby]

Should be green.

[bf4]

I don't think we want this to be instance readable/writable? Do we want these to be inheritable?

[bf4]

re: inhertiable, yes, oops

-          base._reflections = self._reflections.try(:dup) || []
+          super
+          base._reflections = _reflections.dup

[bf4]

Closed by #1356