Serializer not found if the association's serializer is namespaced but the model is not

[Hirurg103]

Hello! I put all the serializers under the API namespace. My problem was that parent serializer
could not find serializers for the associated array of objects. I added the following patch to my
codebase to temporary fix this issue:

#lib/active_model_serializers/lazy_association_patch.rb

# AMS v0.10.7 doesn't respect `namespace` option in the `has_many` association
#
#   class API::UserSerializer < ActiveModel::Serializer
#     has_many :changesets, namespace: API
#   end
#
# To make AMS take in the account namespace when it finds serializer for collection's objects
# has been patched `instantiate_serializer` method in the `ActiveModel::Serializer::LazyAssociation`

require 'active_model/serializer/lazy_association'
class ActiveModel::Serializer::LazyAssociation
  def instantiate_serializer(object)
    serializer_options = association_options.fetch(:parent_serializer_options).except(:serializer)
    serializer_options[:serializer_context_class] = association_options.fetch(:parent_serializer).class
    serializer = reflection_options.fetch(:serializer, nil)
    serializer_options[:serializer] = serializer if serializer

    # forward namespace to the collection serializer
    serializer_options[:namespace]  = reflection_options[:namespace] if reflection_options[:namespace]

    serializer_class.new(object, serializer_options)
  end
end

Then I looked into the test suite for AMS and was able to reproduce this bug with fixtures which are used in the AMS tests

class Post < ::Model
  associations :comments

  def latest_comments
    comments[0..3]
  end
end
class Comment < ::Model; end

class ResourceNamespace
  class PostSerializer < ActiveModel::Serializer
    has_many :latest_comments, namespace: ResourceNamespace
 end
  class CommentSerializer     < ActiveModel::Serializer; end
end

@comment = Comment.new
@post = Post.new(comments: [@comment])
@post_serializer = ResourceNamespace::PostSerializer.new(@post)

@post_serializer.associations.first.association.lazy_association.serializer.first
=> nil

But it should be ResourceNamespace::CommentSerializer

I've added a failing test which tests serializing of not namespaced objects using namespaced serializers and the fix above seems to made it green

I plan to open a PR related to this bug.

--
It would be cool to omit namespace: API every time I define associations in a namespaced serializer

[Hirurg103]

Hi @bf4, do you think it is mine changes broke the build?

[Hirurg103]

I think this can be closed now because #2296 is merged. Thanks @bf4