StoreModel

Work with JSON-backed attributes as ActiveRecord-ish models

Monthly Downloads: 68,065

Programming language: Ruby

License: MIT License

Tags: ORM/ODM Extensions     JSON     Rails     Ruby     Active Record     PostgreSQL    

Latest version: v1.3.0

README

StoreModel

StoreModel gem allows you to wrap JSON-backed DB columns with ActiveModel-like classes.

• 💪 Powered with Attributes API. You can use a number of familiar types or write your own
• 🔧 Works like ActiveModel. Validations, enums and nested attributes work very similar to APIs provided by Rails
• 1️⃣ Follows single responsibility principle. Keep the logic around the data stored in a JSON column separated from the model
• 👷‍♂️ Born in production.

class Configuration
  include StoreModel::Model

  attribute :model, :string
  enum :status, %i[active archived], default: :active

  validates :model, :status, presence: true
end

class Product < ApplicationRecord
  attribute :configuration, Configuration.to_type
end

Why should I wrap my JSON columns?

Imagine that you have a model Product with a jsonb column called configuration. This is how you likely gonna work with this column:

product = Product.find(params[:id])
if product.configuration["model"] == "spaceship"
  product.configuration["color"] = "red"
end
product.save

This approach works fine when you don't have a lot of keys with logic around them and just read the data. However, when you start working with that data more intensively–you may find the code a bit verbose and error-prone.

For instance, try to find a way to validate :model value to be required. Despite of the fact, that you'll have to write this validation by hand, it violates the single-responsibility principle: why parent model (Product) should know about the logic related to a child (Configuration)?

📖 Read more about the motivation in the Wrapping JSON-based ActiveRecord attributes with classes post

Getting started

Start with creating a class for representing the hash as an object:

class Configuration
  include StoreModel::Model

  attribute :model, :string
  attribute :color, :string
end

Attributes should be defined using Rails Attributes API. There is a number of types available out of the box, and you can always extend the type system.

Register the field in the ActiveRecord model class:

class Product < ApplicationRecord
  attribute :configuration, Configuration.to_type
end

When you're done, the initial snippet could be rewritten in the following way:

product = Product.find(params[:id])
if product.configuration.model == "spaceship"
  product.configuration.color = "red"
end
product.save

Usage note: Rails and assigning Arrays/Hashes to records

• Assigned attributes must be a String, Hash, Array of Hashes, or StoreModel. For example, if the attributes are coming from a controller, be sure to convert any ActionController::Parameters as needed.
• Any changes made to a StoreModel instance requires the attribute be re-assigned; Rails doesn't track mutations of objects. For example: self.my_stored_models = my_stored_models.map(&:as_json)

Documentation

1. [Installation](./docs/installation.md)
2. StoreModel::Model API:
   • [Validations](./docs/validations.md)
   • [Enums](./docs/enums.md)
   • [Nested models](./docs/nested_models.md)
   • [Unknown attributes](./docs/unknown_attributes.md)
3. [Array of stored models](./docs/array_of_stored_models.md)
4. [One of](./docs/one_of.md)
5. [Alternatives](./docs/alternatives.md)
6. [Defining custom types](./docs/defining_custom_types.md)

Credits

Initially sponsored by Evil Martians.

License

The gem is available as open source under the terms of the MIT License.