Inheritance of serializer

[givigier]

class ApplicationSerializer < ActiveModel::Serializer
  attributes :id
  def id
    "test"
  end
end

class CustomerSerializer < ApplicationSerializer
end

I'm trying to use something like this on branch master AMS but it does not work. When I use CustomerSerializer, it does include the attribute :id. Is it possible to do this on AMS?

[bf4]

Try defining read_attribute_for_serialization(attr) on your model and handle id there

Otherwise, we'll need some more information of

• what you're trying to serializer and
• with what data
• what you expected
• what you saw
• what you tried
• ruby flavor and version, rails version

[bf4]

Also, if you could help improve https://github.com/rails-api/active_model_serializers/blob/master/CONTRIBUTING.md#how-can-i-help that would be great, too :)

(and https://github.com/rails-api/active_model_serializers#getting-help )

[givigier]

Thanks @bf4. I could ask this on Stackoverflow. Could you close this issue please?

[beauby]

@givigier Closing for now, please post the link of the StackOverflow question here if you do open one.

[bf4]

(And link from your question here, as well.)

[givigier]

http://stackoverflow.com/questions/32722921/inheritance-of-serializer

[givigier]

I guess that it's a bug. I'll try to explain exactly what I did.
I have two serializers, first is ApplicationSerializer and the second is CompanySerializer that inherits of ApplicationSerializer.

class ApplicationSerializer < ActiveModel::Serializer
  def id
    object.slug
  end
end

class V1::CompanySerializer < ApplicationSerializer
  attributes :id, :email
end

When I run on branch: '0-10-stable' I got:

{"id"=>"company-1", "email"=>"[email protected]"}

"company-1" is the slug of company with email [email protected]

When I run on branch: 'master' I got:

{"id"=>"1", "email"=>"[email protected]"}

In this case, slug is not setted as id. It also does not work when I try to use concerns like this:

module SerializerSluggable
  extend ActiveSupport::Concern

  def id
    object.slug
  end
end

require 'concerns/serializer_slugglable'
class V1::CompanySerializer <  ActiveModel::Serializer
  include SerializerSluggable

  attributes :id, :email
end

I got exactly the same result:

When I run on branch: '0-10-stable' I got:

{"id"=>"company-1", "email"=>"[email protected]"}

"company-1" is the slug of company with email [email protected]

When I run on branch: 'master' I got:

{"id"=>"1", "email"=>"[email protected]"}

My rails version is 4.2.2 and ruby version is 2.2.0.

[givigier]

@bf4 @beauby is there any info i could post here to explain better?

[NullVoxPopuli]

what happens if you do:

resource = SerializableResource.new(@company, serializer: V1::CompanySerializer)
resource.serializer.id

?

[givigier]

resource = ActiveModel::SerializableResource.new(@company, serializer: V1::CompanySerializer)
resource.serializer.id

return NoMethodError: undefined method `id' for V1::CompanySerializer:Class

[NullVoxPopuli]

well, that didn't do what I thought it would...

anyway,
I'll see if I can re-create your scenario in a test and debug a bit

[bf4]

I'm guessing the bug is in Serializer._attribute(*args) that conditionally defines attribute methods on the serializer , and that sonething is wrong in one of them

What's

ApplicationSerializer.instance_method(:id).source_location
ApplicationSerializer.instance_method(:id).source

And

CompanySerializer.instance_method(:id).source_location
CompanySerializer.instance_method(:id).source

And for each serializer

Serializer._attributes
serializer.attributes

On a SerializableResource you can call .serializer

[beauby]

As you can see here, if the method id is defined on the serializer, that is what will be used as id. In your case, it seems like the id method is not defined on the inherited serializer. Could you post the output of what @bf4 suggested? That would probably help solve the issue pretty quickly.

[givigier]

class Company < ActiveRecord::Base
end

Company is an ActiveRecord model. It's not necessary to add read_attribute_for_serialization(attr) or am I wrong?

@beauby I added id on serializer too and it does not work 😢

class ApplicationSerializer < ActiveModel::Serializer
  def id
    object.slug
  end
end

class V1::CompanySerializer < ApplicationSerializer
  attributes :id, :email
end

It only works when I'm using branch: '0-10-stable', on master it's broken.

[beauby]

Company is an ActiveRecord model. It's not necessary to add read_attribute_for_serialization(attr) or am I wrong?

You're right about this.

In order to help you, we still need the output of:

ApplicationSerializer.instance_method(:id).source_location
ApplicationSerializer.instance_method(:id).source

CompanySerializer.instance_method(:id).source_location
CompanySerializer.instance_method(:id).source

ApplicationSerializer._attributes
ApplicationSerializer.attributes

CompanySerializer._attributes
CompanySerializer.attributes

[givigier]

ApplicationSerializer.instance_method(:id).source_location

["/Users/givigier/Sites/agrid-api/app/serializers/application_serializer.rb", 4]

ApplicationSerializer.instance_method(:id).source

" def id\n object.slug\n end\n"

V1::CompanySerializer.instance_method(:id).source_location

["/Users/givigier/Sites/agrid-api/app/serializers/v1/company_serializer.rb", 9]

V1::CompanySerializer.instance_method(:id).source

" def id\n object.slug\n end\n"

ApplicationSerializer._attributes

[:id]

ApplicationSerializer.attributes

[]

V1::CompanySerializer._attributes

[:id, :email]

V1::CompanySerializer.attributes

[]

[beauby]

So what happens is that, in your parent serializer (ApplicationSerializer), you define the method id, which get inherited to CompanySerializer. However, when you latter call attributes :id, :email in CompanySerializer, this overrides the custom id method inherited from ApplicationSerializer, and replaces it with a stock def id; object.id; end.
This problem arrises only with the id attribute, because we somehow have to disable the check whether an id method already exists on the serializer when adding a stock one due to an attributes call (https://github.com/rails-api/active_model_serializers/blob/master/lib/active_model/serializer.rb#L65).
I'll investigate this more thoroughly, but in the meantime, you could use a concern that you would include at the end of your serializer definition.

[beauby]

@givigier Could you test #1195 and confirm it fixes your issue?

[givigier]

It fixes the issue, thanks. I was going to try contributing but you fix fastly 👍

[givigier]

@beauby Can I close the issue?

[beauby]

Sure 👍