How to update json column in Rails? - ruby-on-rails

Question

I have a json column in my Categories table and I want to update each category record with a translation from a json file. I have built the json file so that it contains a categories array and each category has a name and a translation, like so:
{
"categories": [
{
"name": "starter",
"message": "Abs/Анти блокираща система (система против боксуване)"
},
{
"name": "alternator",
"message": "Алтернатор"
}
...
]
}
I want every category record to be updated with the language key as well as the translation from the file, like so:
{ bg: 'translation from file' }
I have this code
file = File.read('app/services/translations/files/bg.json')
data = JSON.parse(file)
language = File.basename(file, '.json')
Translations::CategoriesMigrator.call(file: data, language: language)
module Translations
class CategoriesMigrator < Service
def initialize(category_repo: Category)
#category_repo = category_repo
end
def call(file:, language:)
file['categories'].each do |category|
found_category = #category_repo.find_by(name: category['name'])
found_category.translated_categories[language] = category['message']
found_category.save
end
end
end
end
Right now I end up having all categories in a single category record. What am I doing wrong?
Update
My db migration looks like this:
class AddTranslatedCategoriesToCategories < ActiveRecord::Migration[5.1]
def change
add_column :categories, :translated_categories, :jsonb, null: false, default: {}
add_index :categories, :translated_categories, using: :gin
end
end

Answer 1

JSON/JSONB is a good choice when you have data that does not fit in the relational model. In most other cases its an anti-pattern since it makes it much harder to query the data and provides no data integrity or normalization.
This case is definitely the later since the underlaying structure is not dynamic. To keep track of translations we just need to know the subject, the language and the translation.
class Category
has_many :category_translations
end
# rails g model category_translation category:belongs_to locale:string text:string
class CategoryTranslation
belongs_to :category
end
You can add a compound index on category_id and locale to enforce uniqueness.
See:
https://www.2ndquadrant.com/en/blog/postgresql-anti-patterns-unnecessary-jsonhstore-dynamic-columns/