Representable::JSON::Collection does not change json output

[Maximilian Schulz]

I have no idea what I am missing, but I must be missing something. My setup is as follows:

# app/representers/api/mandates_representer.rb

module Api

  module MandatesRepresenter

    include Representable::JSON::Collection

    items extend: MandateRepresenter, class: Mandate

  end

end

# app/representers/api/mandate_representer.rb

module Api

  module MandateRepresenter

    include Roar::Representer::JSON

    property :id

    property :reference

  end

end

Using it with a single mandate, it works perfecty:

Mandate.first.extend(Api::MandateRepresenter).to_json

# => "{\"id\":1,\"reference\":"my-ref"}"

But when using it on the collection, it just renders all attributes:

Mandate.all.extend(Api::MandatesRepresenter).to_json

# => "[{\"id\":2,\"reference\":\"0987654321\",\"ip\":null,\"created_at\":\"2014-06-11T13:52:06.841Z\",\"updated_at\":\"2014-06-11T13:52:06.841Z\"}]"

Any ideas what I am missing?

[Nick Sutterer]

Hey Max,

can you try something like the following?

  [Mandate.last].extend(Api::MandatesRepresenter).to_json

It might be ActiveRecord's magic that gives us trouble.

Nick

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[Maximilian Schulz]

Unfortunately, the same result. I also tried:

Mandate.all.to_a

But still the same. While checking the github issues I came across an issue which looked a bit similar. Perhaps this helps:

Mandate.all.extend(Api::MandatesRepresenter).singleton_class.ancestors

# => [#<Class:#<Mandate::ActiveRecord_Relation:0x00000106983c10>>, Api::MandatesRepresenter, Representable::Hash::Collection, Representable, Representable::Hash, Mandate::ActiveRecord_Relation, ActiveRecord::Delegation::ClassSpecificRelation, ActiveRecord::Relation, ActiveRecord::FinderMethods, ActiveRecord::Calculations, ActiveRecord::SpawnMethods, ActiveRecord::QueryMethods, ActiveRecord::Batches, ActiveRecord::Explain, ActiveRecord::Delegation, Object, ActiveSupport::Dependencies::Loadable, PP::ObjectMixin, JSON::Ext::Generator::GeneratorMethods::Object, Kernel, BasicObject]

By the way, the "old api" is working as expected. Using "respond_with merchant.mandates.to_a, represent_items_with: MandateRepresenter" gives the expected result.

[Nick Sutterer]

Ok, then please do this

[Mandate.last].extend(Api::MandatesRepresenter).method(:to_json).source_location

To find out where the bloody to_json method comes from. Thanks

[Maximilian Schulz]

Ok, that seems to be wrong :)

[Mandate.last].extend(Api::MandatesRepresenter).method(:to_json).source_location

# => ["/Users/namxam/.rvm/gems/ruby-2.1.2/gems/activesupport-4.1.0/lib/active_support/core_ext/object/json.rb", 31]

 

[Nick Sutterer]

Yeah that's what I was expecting, ActiveSupport is polluting your object. Try using Decorator instead.

class MandateRepresenter < Representable::Decorator

and then

MandatesRepresenter.new([Mandate.last]).to_json

Sorry for that but this is not representable's fault ;)

--

[Steve V]

Is there a way to work around this other than decorators? I have been beating head against my desk for some time thinking I was doing something wrong. If there's no workaround, maybe the representable docs can be updated somewhere to indicate the issue, so at least people don't waste time. 

[Nick Sutterer]

The problem here is, we don't know when ActiveSupport kills our representer methods. This is really not my fault but Rails' let's-extend-every-object-with-some-arbitrary-methods. I personally never came across this issue, maybe you can isolate the problem in a tiny Rails app and send it to me?

I'd love to go and see if I can fix it! Thanks!!!

[Steve Valaitis]

I don't blame you at all. I know how invasive ActiveSupport can be. Here's a repo that shows both this issue, and the failure to extend multiple modules. There's a test file in test/models/representers_test.rb

https://github.com/dnd/roar_collection_clobbering

It's a rails 4 project, so I think you should be able to just bundle, and then run rake.

[Steve V]

Is there a specific method you use to try and track down this stuff? Good places to set breakpoints, and such? I've debugged some stuff like this in AS before, and it wasn't fun.

[Nick Sutterer]

My method is usually puts and raise and trying not to get too frustrated... 

Sorry I totally missed the example app you made - I'll have a quick look. Thanks for reminding me :)

Nick

[Nick Sutterer]

I was able to make it work by simply adding this line to your representer:

require 'representable/json/collection'

Now, the question is... WHYYYY?

[Nick Sutterer]

Should be fixed, please upgrade representable to 2.0.4.

https://github.com/apotonick/representable/commit/2fdc9a7d0924f726c2550bd910bc47118cfb631c