Add attributes to existing resources

This guide will show you how to add attributes to existing resources in order to change and retrieve your custom attributes in API endpoints.

For this how-to, we are going to add a new boolean attribute called accept_reviews to the product resource. This attribute will be part of the product response in the API endpoints.

Add the new attribute to existing resources

To add new attributes to existing resources, you need to create a migration file and run the migration.

Create a migration file

To create a migration file, run the following command:

bin/rails g migration add_accept_reviews_to_spree_products accept_reviews:boolean

This will create a migration file in db/migrate with similar content:

class AddAcceptReviewsToSpreeProducts < ActiveRecord::Migration[7.0]
  def change
    add_column :spree_products, :accept_reviews, :boolean
  end
end

Run the migration

To run the migration, run the following command:

bin/rails db:migrate

Add the new attribute to the serializer

In order to expose this field to API clients, we'll need to add a JSON field to the products API. We could just copy-paste the product.json.jbuilder view from Solidus and add the field there, but then we would need to remember to update our custom view every time the original view is changed.

Instead, Solidus provides a more manageable way to add attributes to API resources via the Spree::Api::Config module. Let's see how we can do it and test it:

config/initializers/spree.rb

# ...
Spree::Api::Config.product_attributes << :accept_reviews

info

Extending the attributes, as shown above, will work for all API resources, not just products. You can find the list of the default available attributes in the Spree::ApiConfiguration class.

From now on, the accept_reviews attribute will be included in the response of the products API.

Allow the new attribute to be updated

In order to allow the new attribute to be updated, we need to add it to the list of permitted attributes in the Spree::PermittedAttributes module. Let's see how we can do it and test it:

config/initializers/spree.rb

# ...
Spree::PermittedAttributes.product_attributes << :accept_reviews

info

Extending the permitted attributes, as shown above, will work for all API resources, not just products. You can find the list of the default available attributes in the Spree::PermittedAttributes and more details about how they are used across the project in Spree::Core::ControllerHelpers::StrongParameters.

From now on, the accept_reviews attribute will be allowed to be updated in the products API.

A special case for Line Items

If you are trying to update a new attribute to the line item resource, you will need an extra step. In fact, for security reasons, the line item attributes do not follow the same pattern as the other resources and you'll need to bypass the restriction by adding the following line to your Spree::PermittedAttributes initializer:

config/initializers/spree.rb

Spree::PermittedAttributes.line_item_attributes << { options: [:some_option] }

Now, you can create line items with the some_option attribute with a similar payload:

{
  line_item: {
    variant_id: 123,
    quantity: 1,
    options: { some_option: "foobar" }
  }
}