CODEWITHSUNDEEP
ruby-on-railsruby-on-rails-4serializationassociationsactive-model-serializers
Marty
Marty

Reputation: 2224

Superclass mismatch for serializer

The serializer for Article has two nested serializers: Author and Chapter. The latter two also have their own individual serializers. I'm using the active_model_serializer gem.

# The nested serializer
class Api::V1::ArticleSerializer < Api::V1::SerializerWithSessionMetadata
  attributes :id, ...
  has_many :authors, root: :authors_attributes
  has_many :chapters, through: :authors, root: :chapters_attributes

  class Api::V1::AuthorSerializer < ActiveModel::Serializer
    ...
  end
  class Api::V1::ChapterSerializer < ActiveModel::Serializer
    ...
  end
end

# The two individual serializers
class Api::V1::AuthorSerializer < Api::V1::SerializerWithSessionMetadata
  ...
end

class Api::V1::ChapterSerializer < Api::V1::SerializerWithSessionMetadata
  ...
end

Problem: I currently sometimes get an error while other times I don't (while making the same server request). If the error happens, I restart the server, make the same request, and the error isn't there.

superclass mismatch for class ArticleSerializer

The error refers to class Api::V1::AuthorSerializer < ActiveModel::Serializer in the nested serializer. It seems to particularly happen when creating a new author record. This uses:

author = @article.authors.build(create_params)
if author.save
  render json: @article, status: :created
end

So this method's render line calls on the nested serializer after created an author. What could be the cause of this behavior?

Is the line class Api::V1::AuthorSerializer < ActiveModel::Serializer correct or should it perhaps inherit from something else? Perhaps it sees the Authors nested serializer higher in hierarchy because it inherits from a higher serializer than its individual serializer does. And as a result uses the nested version when it should use its individual version.

If I let the nested version inherit from Api::V1::SerializerWithSessionMetadata instead, then the error is gone. However, the disadvantage then is that it repeats the attributes from the meta serializer for each individual author and chapter in the article serializer.

Upvotes: 2

Views: 445

Answers (1)

Tetiana Chupryna
Tetiana Chupryna

Reputation: 1074

My guess is that problem is in namespace for nested serializer. When you create a class within other one, actually, you create a class inside other one's namespace. And inner class doesn't inherit anything from outer one except its name. So your inner AuthorSerializer can be called as Api::V1::ArticleSerializer::Api::V1::AuthorSerializer So try to rename your classes

class Api::V1::ArticleSerializer < Api::V1::SerializerWithSessionMetadata
  ...

  class AuthorSerializer < ActiveModel::Serializer
    ...
  end

  class ChapterSerializer < ActiveModel::Serializer
    ...
  end
end

# The two individual serializers
class Api::V1::AuthorSerializer < Api::V1::SerializerWithSessionMetadata
  ...
end

class Api::V1::ChapterSerializer < Api::V1::SerializerWithSessionMetadata
  ...
end

Upvotes: 1

Related Questions