Getting a TypeError when calling obj.i18n.pluck

[mendelgusmao]

When I try to pluck an attribute from a model that uses the jsonb backend, it raises a TypeError (no implicit conversion of Mobility::Arel::Nodes::Jsonb into String).

Context

I'm using Mobility 0.8.4, Rails 5.1.6 (ActiveRecord 5.1.6), PostgreSQL 10. Here is an excerpt of my code:

# initializers/mobility.rb
Mobility.configure do |config|
  config.default_backend = :jsonb
  config.accessor_method = :translates
  config.query_method = :i18n
  config.default_options[:default] = proc { |attribute| self[attribute.to_sym] }
  config.default_options[:dirty] = true
end

# models/skill.rb
class Skill < ApplicationRecord
  extend Mobility
  ...
  translates :name 
end

# db/schema.rb
create_table "skills" do |t|
  ...
  t.jsonb "name", default: {}, using: 'gin'
  ...
end

Actual Behavior

irb(main):001:0> Skill.pluck(:name).take(5)
   (1.9ms)  SELECT "skills"."name" FROM "skills"
=> [{"pt-BR"=>"Ruby"}, {"pt-BR"=>"Java"}, {"pt-BR"=>"PHP"}, {"pt-BR"=>"Python"}, {"pt-BR"=>"C++"}]

irb(main):002:0> Skill.i18n.pluck(:name).take(5)
Traceback (most recent call last):
        1: from (irb):2
TypeError (no implicit conversion of Mobility::Arel::Nodes::Jsonb into String)

Thanks for the support!

[shioyama]

This looks a bit fishy to me:

config.default_options[:default] = proc { |attribute| self[attribute.to_sym] }

what if you take that out?

[shioyama]

Also, please post Gemfile or mention what other gems might be involved.

[mendelgusmao]

This looks a bit fishy to me:

config.default_options[:default] = proc { |attribute| self[attribute.to_sym] }

what if you take that out?

Removing the :default option didn't change anything but your clue made me remove the :dirty option and now it works. Thank you!

[shioyama]

Hmm... ok so maybe there's a compatibility issue with Dirty then.

[shioyama]

Re-opened this since I'd like to figure out where the compatibility issue is.

[mendelgusmao]

And maybe an incompatibility with :fallbacks and :default. Using the same setup, using fallbacks = :en => :'pt-BR' or the aforementioned default lambda:

irb(main):005:0> Mobility.with_locale(:en) { Industry.i18.pluck(:name).take(5) }
   (0.8ms)  SELECT ("industries"."name" ->> 'en') FROM "industries"
=> [nil, nil, nil, nil, nil]

Which is pretty comprehensible because only the :en translation is loaded. But what I found weird is that the lambda is not even being called. Should I open another issue?

[shioyama]

Should I open another issue?

No, this is not an issue, it is simply not supported. When you call pluck, you are doing a query, and things like dirty tracking and fallbacks are not supported on query methods. Although fallbacks on querying may be supported in the future, see: #51.

However, the problem you originally found in this issue would be a bug, once I can confirm it's not related to anything outside of Mobility.

[shioyama]

Ok I've reproduced this, seems to only happen in Rails 5.1.x and not 5.2.x.

[shioyama]

@mendelgusmao #309 should fix this issue with dirty enabled. I'll merge and release the fix once specs pass.

[shioyama]

This is fixed on master and on the 0-8-stable branch. Please try the latter (gem 'mobility', github: 'shioyama/mobility', branch: '0-8-stable') and see if it works.

[shioyama]

Fix released in 0.8.7.

[mendelgusmao]

Thank you, @shioyama