Skip serialization for all JSON/JSONB attributes in activerecord plugin

[vojtad]

Use type_for_attribute instead of columns_hash to check whether an attribute type is JSON or JSONB. Serialization is now skipped not only for database attributes but also for attributes defined using Attributes API.

This is a breaking change. Do you want to hide it behind a feature flag or how should I approach this?

[janko]

Thanks for the patch, it looks good to me 👍🏻 In what way is this a breaking change?

[vojtad]

If you have attribute :avatar_data, :json defined in your model then avatar_data returned a String and you could call JSON.parse on it to get an object before.

With this patch avatar_data returns an object without any need for deserializing it because it never gets serialized since the attribute is a JSON attribute.

Here is an example code which throws an exception when calling `JSON.parse` when run with this patch.

require 'active_record'
require 'minitest'
require 'shrine'

require_relative '../test/support/file_helper'
require_relative '../test/support/shrine_helper'

include FileHelper
include ShrineHelper

ActiveRecord::Base.establish_connection(
  adapter:  "sqlite3",
  database: ":memory:",
)

ActiveRecord::Base.connection.create_table(:users) do |t|
  t.string :name
end

@shrine = shrine do
  plugin :activerecord
  plugin :backgrounding
end

user_class = Class.new(ActiveRecord::Base)
user_class.table_name = :users
user_class.class_eval do
  # needed for translating validation errors
  def self.model_name
    ActiveModel::Name.new(self, nil, "User")
  end

  attribute :avatar_data, :json
end
user_class.include @shrine::Attachment.new(:avatar)

user = user_class.new

pp user.avatar_data

user.avatar = fakeio
user.save!

pp user.avatar_data

# user.avatar_data used to be a String so we can call JSON.parse to deserialize it
pp JSON.parse(user.avatar_data)