Class: Grape::Entity

Inherits:
Object
  • Object
show all
Defined in:
lib/grape_entity/entity.rb,
lib/grape_entity/delegator.rb,
lib/grape_entity/delegator/base.rb,
lib/grape_entity/delegator/hash_object.rb,
lib/grape_entity/delegator/plain_object.rb,
lib/grape_entity/delegator/fetchable_object.rb,
lib/grape_entity/delegator/openstruct_object.rb

Overview

An Entity is a lightweight structure that allows you to easily represent data from your application in a consistent and abstracted way in your API. Entities can also provide documentation for the fields exposed.

Entities are not independent structures, rather, they create representations of other Ruby objects using a number of methods that are convenient for use in an API. Once you've defined an Entity, you can use it in your API like this:

Examples:

Entity Definition


module API
  module Entities
    class User < Grape::Entity
      expose :first_name, :last_name, :screen_name, :location
      expose :field, documentation: { type: "string", desc: "describe the field" }
      expose :latest_status, using: API::Status, as: :status, unless: { collection: true }
      expose :email, if: { type: :full }
      expose :new_attribute, if: { version: 'v2' }
      expose(:name) { |model, options| [model.first_name, model.last_name].join(' ') }
    end
  end
end

Usage in the API Layer


module API
  class Users < Grape::API
    version 'v2'

    desc 'User index', { params: API::Entities::User.documentation }
    get '/users' do
      @users = User.all
      type = current_user.admin? ? :full : :default
      present @users, with: API::Entities::User, type: type
    end
  end
end

Defined Under Namespace

Modules: DSL, Delegator

Class Attribute Summary collapse

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(object, options = {}) ⇒ Entity

Returns a new instance of Entity.



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# File 'lib/grape_entity/entity.rb', line 396

def initialize(object, options = {})
  @object = object
  @delegator = Delegator.new object
  @options = options
end

Class Attribute Details

.exposures ⇒ Hash

Returns exposures that have been declared for this Entity or ancestors. The keys are symbolized references to methods on the containing object, the values are the options that were passed into expose.

Returns:

  • (Hash) —

    of exposures



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# File 'lib/grape_entity/entity.rb', line 106

def exposures
  @exposures
end

.formatters ⇒ Hash

Returns all formatters that are registered for this and it's ancestors

Returns:

  • (Hash) —

    of formatters



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# File 'lib/grape_entity/entity.rb', line 110

def formatters
  @formatters
end

.nested_attribute_names ⇒ Object

Returns the value of attribute nested_attribute_names.



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# File 'lib/grape_entity/entity.rb', line 111

def nested_attribute_names
  @nested_attribute_names
end

.nested_exposures ⇒ Object

Returns the value of attribute nested_exposures.



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# File 'lib/grape_entity/entity.rb', line 112

def nested_exposures
  @nested_exposures
end

.root_exposures ⇒ Object

Returns the value of attribute root_exposures.



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# File 'lib/grape_entity/entity.rb', line 107

def root_exposures
  @root_exposures
end

Instance Attribute Details

#delegator ⇒ Object (readonly)

Returns the value of attribute delegator.



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# File 'lib/grape_entity/entity.rb', line 45

def delegator
  @delegator
end

#object ⇒ Object (readonly)

Returns the value of attribute object.



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# File 'lib/grape_entity/entity.rb', line 45

def object
  @object
end

#options ⇒ Object (readonly)

Returns the value of attribute options.



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# File 'lib/grape_entity/entity.rb', line 45

def options
  @options
end

Class Method Details

.documentation ⇒ Object

Returns a hash, the keys are symbolized references to fields in the entity, the values are document keys in the entity's documentation key. When calling

docmentation, any exposure without a documentation key will be ignored.



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# File 'lib/grape_entity/entity.rb', line 207

def self.documentation
  @documentation ||= exposures.each_with_object({}) do |(attribute, exposure_options), memo|
    if exposure_options[:documentation].present?
      memo[key_for(attribute)] = exposure_options[:documentation]
    end
  end
end

.expose(*args, &block) ⇒ Object

This method is the primary means by which you will declare what attributes should be exposed by the entity.

Parameters:

  • options (Hash) —

    a customizable set of options



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# File 'lib/grape_entity/entity.rb', line 148

def self.expose(*args, &block)
  options = merge_options(args.last.is_a?(Hash) ? args.pop : {})

  if args.size > 1
    fail ArgumentError, 'You may not use the :as option on multi-attribute exposures.' if options[:as]
    fail ArgumentError, 'You may not use block-setting on multi-attribute exposures.' if block_given?
  end

  fail ArgumentError, 'You may not use block-setting when also using format_with' if block_given? && options[:format_with].respond_to?(:call)

  options[:proc] = block if block_given? && block.parameters.any?

  @nested_attributes ||= []

  # rubocop:disable Style/Next
  args.each do |attribute|
    if @nested_attributes.empty?
      root_exposures[attribute] = options
    else
      orig_attribute = attribute.to_sym
      attribute = "#{@nested_attributes.last}__#{attribute}".to_sym
      nested_attribute_names[attribute] = orig_attribute
      options[:nested] = true
      nested_exposures.deep_merge!(@nested_attributes.last.to_sym  => { attribute => options })
    end

    exposures[attribute] = options

    # Nested exposures are given in a block with no parameters.
    if block_given? && block.parameters.empty?
      @nested_attributes << attribute
      block.call
      @nested_attributes.pop
    end
  end
end

.format_with(name, &block) ⇒ Object

This allows you to declare a Proc in which exposures can be formatted with. It take a block with an arity of 1 which is passed as the value of the exposed attribute.

Examples:

Formatter declaration


module API
  module Entities
    class User < Grape::Entity
      format_with :timestamp do |date|
        date.strftime('%m/%d/%Y')
      end

      expose :birthday, :last_signed_in, format_with: :timestamp
    end
  end
end

Formatters are available to all decendants


Grape::Entity.format_with :timestamp do |date|
  date.strftime('%m/%d/%Y')
end

Parameters:

  • name (Symbol) —

    the name of the formatter

  • block (Proc) —

    the block that will interpret the exposed attribute



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# File 'lib/grape_entity/entity.rb', line 241

def self.format_with(name, &block)
  fail ArgumentError, 'You must pass a block for formatters' unless block_given?
  formatters[name.to_sym] = block
end

.inherited(subclass) ⇒ Object 



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# File 'lib/grape_entity/entity.rb', line 115

def self.inherited(subclass)
  subclass.exposures = exposures.try(:dup) || {}
  subclass.root_exposures = root_exposures.try(:dup) || {}
  subclass.nested_exposures = nested_exposures.try(:dup) || {}
  subclass.nested_attribute_names = nested_attribute_names.try(:dup) || {}
  subclass.formatters = formatters.try(:dup) || {}
end

.present_collection(present_collection = false, collection_name = :items) ⇒ Object

This allows you to present a collection of objects.

When false (default) every object in a collection to present will be wrapped separately into an instance of your presenter.

Examples:

Entity Definition


module API
  module Entities
    class User < Grape::Entity
      expose :id
    end

    class Users < Grape::Entity
      present_collection true
      expose :items, as: 'users', using: API::Entities::Users
      expose :version, documentation: { type: 'string',
                                        desc: 'actual api version',
                                        required: true }

      def version
        options[:version]
      end
    end
  end
end

Usage in the API Layer


module API
  class Users < Grape::API
    version 'v2'

    # this will render { "users" : [ { "id" : "1" }, { "id" : "2" } ], "version" : "v2" }
    get '/users' do
      @users = User.all
      present @users, with: API::Entities::Users
    end

    # this will render { "user" : { "id" : "1" } }
    get '/users/:id' do
      @user = User.find(params[:id])
      present @user, with: API::Entities::User
    end
  end
end

Parameters:

  • present_collection (true or false) (defaults to: false) —

    when true all objects will be available as items in your presenter instead of wrapping each object in an instance of your presenter.

  • collection_name (Symbol) (defaults to: :items) —

    the name of the collection accessor in your entity object. Default :items



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# File 'lib/grape_entity/entity.rb', line 341

def self.present_collection(present_collection = false, collection_name = :items)
  @present_collection = present_collection
  @collection_name = collection_name
end

.represent(objects, options = {}) ⇒ Object

This convenience method allows you to instantiate one or more entities by passing either a singular or collection of objects. Each object will be initialized with the same options. If an array of objects is passed in, an array of entities will be returned. If a single object is passed in, a single entity will be returned.

Parameters:

  • objects (Object or Array) —

    One or more objects to be represented.

  • options (Hash) (defaults to: {}) —

    Options that will be passed through to each entity representation.

Options Hash (options):

  • :root (String or false) —

    override the default root name set for the entity. Pass nil or false to represent the object or objects with no root name even if one is defined for the entity.

  • :serializable (true or false) —

    when true a serializable Hash will be returned

  • :only (Array) —

    all the fields that should be returned

  • :except (Array) —

    all the fields that should not be returned



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# File 'lib/grape_entity/entity.rb', line 363

def self.represent(objects, options = {})
  if objects.respond_to?(:to_ary) && ! @present_collection
    root_element =  root_element(:collection_root)
    inner = objects.to_ary.map { |object| new(object, { collection: true }.merge(options)).presented }
  else
    objects = { @collection_name => objects } if @present_collection
    root_element = root_element(:root)
    inner = new(objects, options).presented
  end

  root_element = options[:root] if options.key?(:root)

  root_element ? { root_element => inner } : inner
end

.root(plural, singular = nil) ⇒ Object

This allows you to set a root element name for your representation.

Examples:

Entity Definition


module API
  module Entities
    class User < Grape::Entity
      root 'users', 'user'
      expose :id
    end
  end
end

Usage in the API Layer


module API
  class Users < Grape::API
    version 'v2'

    # this will render { "users" : [ { "id" : "1" }, { "id" : "2" } ] }
    get '/users' do
      @users = User.all
      present @users, with: API::Entities::User
    end

    # this will render { "user" : { "id" : "1" } }
    get '/users/:id' do
      @user = User.find(params[:id])
      present @user, with: API::Entities::User
    end
  end
end

Parameters:

  • plural (String) —

    the root key to use when representing a collection of objects. If missing or nil, no root key will be used when representing collections of objects.

  • singular (String) (defaults to: nil) —

    the root key to use when representing a single object. If missing or nil, no root key will be used when representing an individual object.



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# File 'lib/grape_entity/entity.rb', line 285

def self.root(plural, singular = nil)
  @collection_root = plural
  @root = singular
end

.root_element(root_type) ⇒ Object

This method returns the entity's root or collection root node, or its parent's

Parameters:

  • root_type: —

    either :collection_root or just :root



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# File 'lib/grape_entity/entity.rb', line 380

def self.root_element(root_type)
  if instance_variable_get("@#{root_type}")
    instance_variable_get("@#{root_type}")
  elsif superclass.respond_to? :root_element
    superclass.root_element(root_type)
  end
end

.unexpose(attribute) ⇒ Object 



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# File 'lib/grape_entity/entity.rb', line 185

def self.unexpose(attribute)
  exposures.delete(attribute)
end

.with_options(options) ⇒ Object

Set options that will be applied to any exposures declared inside the block.

Examples:

Multi-exposure if


class MyEntity < Grape::Entity
  with_options if: { awesome: true } do
    expose :awesome, :sweet
  end
end


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# File 'lib/grape_entity/entity.rb', line 198

def self.with_options(options)
  (@block_options ||= []).push(valid_options(options))
  yield
  @block_options.pop
end

Instance Method Details

#documentation ⇒ Object 



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# File 'lib/grape_entity/entity.rb', line 410

def documentation
  self.class.documentation
end

#except_fields(options, for_attribute = nil) ⇒ Object 



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# File 'lib/grape_entity/entity.rb', line 480

def except_fields(options, for_attribute = nil)
  return nil unless options[:except]

  @except_fields ||= options[:except].each_with_object({}) do |attribute, allowed_fields|
    if attribute.is_a?(Hash)
      attribute.each do |attr, nested_attrs|
        allowed_fields[attr] ||= []
        allowed_fields[attr] += nested_attrs
      end
    else
      allowed_fields[attribute] = true
    end
  end.symbolize_keys

  if for_attribute && @except_fields[for_attribute].is_a?(Array)
    @except_fields[for_attribute]
  elsif for_attribute.nil?
    @except_fields
  end
end

#exposures ⇒ Object 



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# File 'lib/grape_entity/entity.rb', line 402

def exposures
  self.class.exposures
end

#formatters ⇒ Object 



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# File 'lib/grape_entity/entity.rb', line 414

def formatters
  self.class.formatters
end

#only_fields(options, for_attribute = nil) ⇒ Object 



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# File 'lib/grape_entity/entity.rb', line 459

def only_fields(options, for_attribute = nil)
  return nil unless options[:only]

  @only_fields ||= options[:only].each_with_object({}) do |attribute, allowed_fields|
    if attribute.is_a?(Hash)
      attribute.each do |attr, nested_attrs|
        allowed_fields[attr] ||= []
        allowed_fields[attr] += nested_attrs
      end
    else
      allowed_fields[attribute] = true
    end
  end.symbolize_keys

  if for_attribute && @only_fields[for_attribute].is_a?(Array)
    @only_fields[for_attribute]
  elsif for_attribute.nil?
    @only_fields
  end
end

#presented ⇒ Object 



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# File 'lib/grape_entity/entity.rb', line 388

def presented
  if options[:serializable]
    serializable_hash
  else
    self
  end
end

#root_exposures ⇒ Object 



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# File 'lib/grape_entity/entity.rb', line 406

def root_exposures
  self.class.root_exposures
end

#serializable_hash(runtime_options = {}) ⇒ Object Also known as: as_json

The serializable hash is the Entity's primary output. It is the transformed hash for the given data model and is used as the basis for serialization to JSON and other formats.

Parameters:

  • runtime_options (Hash) (defaults to: {}) —

    Any options you pass in here will be known to the entity representation, this is where you can trigger things from conditional options etc.



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# File 'lib/grape_entity/entity.rb', line 425

def serializable_hash(runtime_options = {})
  return nil if object.nil?

  opts = options.merge(runtime_options || {})

  root_exposures.each_with_object({}) do |(attribute, exposure_options), output|
    next unless should_return_attribute?(attribute, opts) && conditions_met?(exposure_options, opts)

    partial_output = value_for(attribute, opts)

    output[self.class.key_for(attribute)] =
      if partial_output.respond_to?(:serializable_hash)
        partial_output.serializable_hash(runtime_options)
      elsif partial_output.is_a?(Array) && partial_output.all? { |o| o.respond_to?(:serializable_hash) }
        partial_output.map(&:serializable_hash)
      elsif partial_output.is_a?(Hash)
        partial_output.each do |key, value|
          partial_output[key] = value.serializable_hash if value.respond_to?(:serializable_hash)
        end
      else
        partial_output
      end
  end
end

#should_return_attribute?(attribute, options) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/grape_entity/entity.rb', line 450

def should_return_attribute?(attribute, options)
  key = self.class.key_for(attribute)
  only = only_fields(options).nil? ||
         only_fields(options).include?(key)
  except = except_fields(options) && except_fields(options).include?(key) &&
           except_fields(options)[key] == true
  only && !except
end

#to_json(options = {}) ⇒ Object 



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# File 'lib/grape_entity/entity.rb', line 503

def to_json(options = {})
  options = options.to_h if options && options.respond_to?(:to_h)
  MultiJson.dump(serializable_hash(options))
end

#to_xml(options = {}) ⇒ Object 



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# File 'lib/grape_entity/entity.rb', line 508

def to_xml(options = {})
  options = options.to_h if options && options.respond_to?(:to_h)
  serializable_hash(options).to_xml(options)
end