clone always clears inclusion list at apply time, but this isn't documented (& not obviously correct)

[dmolesUC]

I want to include certain associations, clone others, and exclude any that aren't explicitly included or cloned. This doesn't seem to be supported, because apply_clones calls exclude_association (via exclude_clone_if_has_many_through), and exclude_association clears the includes array.
This isn't explicitly documented, and I had to discover it by stepping through in the debugger.

It looks from the code as though this is only meant to happen for has_many_through relations. However, even when association.options[:through] is nil, exclude_association(association.options[:through]) still gets called, and exclude_association clears the includes array even if its argument is nil.

It seems like it would be more correct for exclude_clone_if_has_many_through to do something like:

def exclude_clone_if_has_many_through(clone_field)
  association = @object_klass.reflect_on_association(clone_field)

  return unless association.macro == :has_many ||
    association.is_a?(::ActiveRecord::Reflection::ThroughReflection)

  through_assoc = association.options[:through]
  return unless through_assoc

  if amoeba.includes.empty? # we're either in exclusive mode or we want to be
    amoeba.exclude_association(through_assoc)
  else # we're in inclusive mode
    amoeba.includes.delete(through_assoc) # no effect if already not included
  end

but I don't know Amoeba well enough yet to know whether this would have other undesirable side effects.

[dmolesUC]

(I might also be using clone wrong, but in that case maybe an exception should be raised here? Or when a nil is passed to exclude_association?)

[benjamin-hull]

This has bitten me today, too, in a slightly different way:

If there are no calls to include_association or exclude_association, but calls to clone in the config, the model is forced into exclusive mode by the fact that clone clears the list (therefore includes is empty, triggering exclusive mode).

This means you can't only clone associations. As it is, I wonder if calling clone should trigger inclusive mode as well.