Custom

Attributes don't need to map to model columns. Define a method with the same name to create a virtual attribute.

Basic Usage

class InvoiceRepresentation < Apiwork::Representation::Base
  attribute :full_title, type: :string

  def full_title
    "#{record.status.upcase}: #{record.number}"
  end
end

The record method returns the current record.

WARNING

Custom attributes require an explicit type. There is no model column to detect from.

Preloading

Custom attributes that access associations cause N+1 queries:

class InvoiceRepresentation < Apiwork::Representation::Base
  attribute :item_count, type: :integer

  def item_count
    record.items.size  # N+1: one query per invoice
  end
end

Use preload: to eager load associations:

class InvoiceRepresentation < Apiwork::Representation::Base
  attribute :item_count, type: :integer, preload: :items

  def item_count
    record.items.size  # Items already loaded
  end
end

The format matches Rails includes:

# Single association
preload: :items

# Multiple associations
preload: [:items, :customer]

# Nested associations
preload: { items: :adjustments }

Apiwork combines preloads with other includes (such as eager-loaded associations) into a single query.