StoreModel gem allows you to wrap JSON-backed DB columns with ActiveModel-like classes.
- ๐ช Powered with Attributes API. You can use a number of familiar types or write your own
- ๐ง Works like ActiveModel. Validations, enums and nested attributes work very similar to APIs provided by Rails
- 1๏ธโฃ Follows single responsibility principle. Keep the logic around the data stored in a JSON column separated from the model
- ๐ทโโ๏ธ 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
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 intensivelyโyou 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
)?
๐ Read more about the motivation in the Wrapping JSON-based ActiveRecord attributes with classes post
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 flagged as dirty, either by reassignment (
self.my_stored_models = my_stored_models.map(&:as_json)
) or bywill_change!
(self.my_stored_models_will_change!
) - Mixing
StoreModel::NestedAttributes
into your model will allow you to useaccepts_nested_attributes_for
in the same way as ActiveRecord.
class Supplier < ActiveRecord::Base
include StoreModel::NestedAttributes
has_many :bicycles, dependent: :destroy
attribute :products, Product.to_array_type
accepts_nested_attributes_for :bicycles, :products, allow_destroy: true
end
This will allow the form builders to work their magic:
<%= form_with model: @supplier do |form| %>
<%= form.fields_for :products do |product_fields| %>
<%= product_fields.text_field :name %>
<% end %>
<% end %>
Resulting in:
<input type="text" name="supplier[products_attributes][0][name]" id="supplier_products_attributes_0_name">
In the controller:
def create
@supplier = Supplier.new(supplier_params)
@supplier.save
end
private
def supplier_params
params.require(:supplier).permit(products_attributes: [:name])
end
- Installation
- StoreModel::Model API:
Initially sponsored by Evil Martians.
The gem is available as open source under the terms of the MIT License.