Serialization

To customize JSON output, especially when Rails is used as an API endpoint. To add gem:

gem 'active_model_serializers', '~> 0.10.0'

CLI

CLI command is available:

rails generate serializer article

generate app/serializers/article_serializer.rb

Attributes can either be declared in a bulky way via attributes :field1, :field2... or one by one:

attribute :field1
attribute :field2

It requires the single attribute declaration:

attribute :description, unless: -> { object.description.nil? }
attribute :some_field, if -> { some_condition }

Use a method to return the value.

attribute :article_count

def article_count
  object.articles.size
end

Beware of N+1 queries

Use the field options when using json adapter:

# Exclude :description field
render json: @list, each_serializer: CatalogSerializer, fields: [:id, :code, :name]

This restriction also apply to computed attributes

Associations are declared in a similar way of ActiveRecords:

belongs_to :user
has_many :article_publications

If not specified, default serializers will be used for serializing relationship

Use the include options when using the json adapter:

# With the above definition, :article_publicaitons is excluded
render json: @list, each_serializer: CatalogSerializer, include: [:user]

Initialize function:

def initialize(object, options = {})
end

Sources:

rails json serialization

Mentionned: