Class: RESTFramework::Serializers::NativeSerializer

Inherits:
BaseSerializer show all
Defined in:
lib/rest_framework/serializers/native_serializer.rb

Overview

This serializer uses ‘.serializable_hash` to convert objects to Ruby primitives (with the top-level being either an array or a hash).

Instance Attribute Summary

Attributes inherited from BaseSerializer

#object

Class Method Summary collapse

Instance Method Summary collapse

Methods inherited from BaseSerializer

#associations, cache_enabled?, fragment_cache_enabled?, #serializable_hash

Constructor Details

#initialize(object = nil, *args, many: nil, model: nil, **kwargs) ⇒ NativeSerializer

Accept/ignore ‘*args` to be compatible with the `ActiveModel::Serializer#initialize` signature.



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# File 'lib/rest_framework/serializers/native_serializer.rb', line 10

def initialize(object=nil, *args, many: nil, model: nil, **kwargs)
  super(object, *args, **kwargs)

  if many.nil?
    # Determine if we are dealing with many objects or just one.
    @many = @object.is_a?(Enumerable)
  else
    @many = many
  end

  # Determine model either explicitly, or by inspecting @object or @controller.
  @model = model
  @model ||= @object.class if @object.is_a?(ActiveRecord::Base)
  @model ||= @object[0].class if
    @many && @object.is_a?(Enumerable) && @object.is_a?(ActiveRecord::Base)

  @model ||= @controller.class.get_model if @controller
end

Class Method Details

.[](key) ⇒ Object

Allow a serializer class to be used as a hash directly in a nested serializer config.



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# File 'lib/rest_framework/serializers/native_serializer.rb', line 356

def self.[](key)
  @_nested_config ||= self.new.get_serializer_config
  return @_nested_config[key]
end

.[]=(key, value) ⇒ Object 



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# File 'lib/rest_framework/serializers/native_serializer.rb', line 361

def self.[]=(key, value)
  @_nested_config ||= self.new.get_serializer_config
  return @_nested_config[key] = value
end

.filter_subcfg(subcfg, fields:, add: false, only: false) ⇒ Object

Filter a single subconfig for specific keys. By default, keys from ‘fields` are removed from the provided `subcfg`. There are two (mutually exclusive) options to adjust the behavior:

`add`: Add any `fields` to the `subcfg` which aren't already in the `subcfg`.
`only`: Remove any values found in the `subcfg` not in `fields`.



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# File 'lib/rest_framework/serializers/native_serializer.rb', line 71

def self.filter_subcfg(subcfg, fields:, add: false, only: false)
  raise "`add` and `only` conflict with one another" if add && only

  # Don't process nil `subcfg`s.
  return subcfg unless subcfg

  if subcfg.is_a?(Array)
    subcfg = subcfg.map(&:to_sym)

    if add
      # Only add fields which are not already included.
      subcfg += fields - subcfg
    elsif only
      subcfg.select! { |c| c.in?(fields) }
    else
      subcfg -= fields
    end
  elsif subcfg.is_a?(Hash)
    subcfg = subcfg.symbolize_keys

    if add
      # Add doesn't make sense in a hash context since we wouldn't know the values.
    elsif only
      subcfg.select! { |k, _v| k.in?(fields) }
    else
      subcfg.reject! { |k, _v| k.in?(fields) }
    end
  else  # Subcfg is a single element (assume string/symbol).
    subcfg = subcfg.to_sym

    if add
      subcfg = subcfg.in?(fields) ? fields : [subcfg, *fields]
    elsif only
      subcfg = subcfg.in?(fields) ? subcfg : []
    else
      subcfg = subcfg.in?(fields) ? [] : subcfg
    end
  end

  return subcfg
end

Instance Method Details

#[](key) ⇒ Object

Allow a serializer instance to be used as a hash directly in a nested serializer config.



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# File 'lib/rest_framework/serializers/native_serializer.rb', line 345

def [](key)
  @_nested_config ||= self.get_serializer_config
  return @_nested_config[key]
end

#[]=(key, value) ⇒ Object 



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# File 'lib/rest_framework/serializers/native_serializer.rb', line 350

def []=(key, value)
  @_nested_config ||= self.get_serializer_config
  return @_nested_config[key] = value
end

#_get_associations_limit ⇒ Object

Get the associations limit from the controller.



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# File 'lib/rest_framework/serializers/native_serializer.rb', line 160

def _get_associations_limit
  return @_get_associations_limit if defined?(@_get_associations_limit)

  limit = @controller&.native_serializer_associations_limit

  # Extract the limit from the query parameters if it's set.
  if query_param = @controller&.native_serializer_associations_limit_query_param
    if @controller.request.query_parameters.key?(query_param)
      query_limit = @controller.request.query_parameters[query_param].to_i
      if query_limit > 0
        limit = query_limit
      else
        limit = nil
      end
    end
  end

  return @_get_associations_limit = limit
end

#_get_controller_serializer_config(fields) ⇒ Object

Get a serializer configuration from the controller. ‘@controller` and `@model` must be set.



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# File 'lib/rest_framework/serializers/native_serializer.rb', line 181

def _get_controller_serializer_config(fields)
  columns = []
  includes = {}
  methods = []
  serializer_methods = {}

  # We try to construct performant queries using Active Record's `includes` method. This is
  # sometimes impossible, for example when limiting the number of associated records returned, so
  # we should only add associations here when it's useful, and using the `Bullet` gem is helpful
  # in determining when that is the case.
  includes_map = {}

  column_names = @model.column_names
  reflections = @model.reflections
  attachment_reflections = @model.attachment_reflections

  fields.each do |f|
    field_config = @controller.class.get_field_config(f)
    next if field_config[:write_only]

    if f.in?(column_names)
      columns << f
    elsif ref = reflections[f]
      sub_columns = []
      sub_methods = []
      field_config[:sub_fields].each do |sf|
        if !ref.polymorphic? && sf.in?(ref.klass.column_names)
          sub_columns << sf
        else
          sub_methods << sf
        end
      end
      sub_config = {only: sub_columns, methods: sub_methods}

      # Apply certain rules regarding collection associations.
      if ref.collection?
        # If we need to limit the number of serialized association records, then dynamically add a
        # serializer method to do so.
        if limit = self._get_associations_limit
          serializer_methods[f] = f
          self.define_singleton_method(f) do |record|
            next record.send(f).limit(limit).as_json(**sub_config)
          end

          # Disable this for now, as it's not clear if this improves performance of count.
          #
          # # Even though we use a serializer method, if the count will later be added, then put
          # # this field into the includes_map.
          # if @controller.native_serializer_include_associations_count
          #   includes_map[f] = f.to_sym
          # end
        else
          includes[f] = sub_config
          includes_map[f] = f.to_sym
        end

        # If we need to include the association count, then add it here.
        if @controller.native_serializer_include_associations_count
          method_name = "#{f}.count"
          serializer_methods[method_name] = method_name
          self.define_singleton_method(method_name) do |record|
            next record.send(f).count
          end
        end
      else
        includes[f] = sub_config
        includes_map[f] = f.to_sym
      end
    elsif ref = reflections["rich_text_#{f}"]
      # ActionText Integration: Define rich text serializer method.
      includes_map[f] = :"rich_text_#{f}"
      serializer_methods[f] = f
      self.define_singleton_method(f) do |record|
        next record.send(f).to_s
      end
    elsif ref = attachment_reflections[f]
      # ActiveStorage Integration: Define attachment serializer method.
      if ref.macro == :has_one_attached
        serializer_methods[f] = f
        includes_map[f] = {"#{f}_attachment": :blob}
        self.define_singleton_method(f) do |record|
          next record.send(f).attachment&.url
        end
      elsif ref.macro == :has_many_attached
        serializer_methods[f] = f
        includes_map[f] = {"#{f}_attachments": :blob}
        self.define_singleton_method(f) do |record|
          # Iterating the collection yields attachment objects.
          next record.send(f).map(&:url)
        end
      end
    elsif @model.method_defined?(f)
      methods << f
    end
  end

  return {
    only: columns,
    include: includes,
    methods: methods,
    serializer_methods: serializer_methods,
    includes_map: includes_map,
  }
end

#_serialize(record, config, serializer_methods) ⇒ Object

Serialize a single record and merge results of ‘serializer_methods`.



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# File 'lib/rest_framework/serializers/native_serializer.rb', line 315

def _serialize(record, config, serializer_methods)
  # Ensure serializer_methods is either falsy, or a hash.
  if serializer_methods && !serializer_methods.is_a?(Hash)
    serializer_methods = [serializer_methods].flatten.map { |m| [m, m] }.to_h
  end

  # Merge serialized record with any serializer method results.
  return record.serializable_hash(config).merge(
    serializer_methods&.map { |m, k| [k.to_sym, self.send(m, record)] }.to_h,
  )
end

#filter_from_request(cfg) ⇒ Object

Filter out configuration properties based on the :except/:only query parameters.



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# File 'lib/rest_framework/serializers/native_serializer.rb', line 114

def filter_from_request(cfg)
  return cfg unless @controller

  except_param = @controller.try(:native_serializer_except_query_param)
  only_param = @controller.try(:native_serializer_only_query_param)
  if except_param && except = @controller.request&.query_parameters&.[](except_param).presence
    if except = except.split(",").map(&:strip).map(&:to_sym).presence
      # Filter `only`, `except` (additive), `include`, `methods`, and `serializer_methods`.
      if cfg[:only]
        cfg[:only] = self.class.filter_subcfg(cfg[:only], fields: except)
      elsif cfg[:except]
        cfg[:except] = self.class.filter_subcfg(cfg[:except], fields: except, add: true)
      else
        cfg[:except] = except
      end

      cfg[:include] = self.class.filter_subcfg(cfg[:include], fields: except)
      cfg[:methods] = self.class.filter_subcfg(cfg[:methods], fields: except)
      cfg[:serializer_methods] = self.class.filter_subcfg(
        cfg[:serializer_methods], fields: except
      )
      cfg[:includes_map] = self.class.filter_subcfg(cfg[:includes_map], fields: except)
    end
  elsif only_param && only = @controller.request&.query_parameters&.[](only_param).presence
    if only = only.split(",").map(&:strip).map(&:to_sym).presence
      # Filter `only`, `include`, and `methods`. Adding anything to `except` is not needed,
      # because any configuration there takes precedence over `only`.
      if cfg[:only]
        cfg[:only] = self.class.filter_subcfg(cfg[:only], fields: only, only: true)
      else
        cfg[:only] = only
      end

      cfg[:include] = self.class.filter_subcfg(cfg[:include], fields: only, only: true)
      cfg[:methods] = self.class.filter_subcfg(cfg[:methods], fields: only, only: true)
      cfg[:serializer_methods] = self.class.filter_subcfg(
        cfg[:serializer_methods], fields: only, only: true
      )
      cfg[:includes_map] = self.class.filter_subcfg(cfg[:includes_map], fields: only, only: true)
    end
  end

  return cfg
end

#get_action ⇒ Object

Get controller action, if possible.



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# File 'lib/rest_framework/serializers/native_serializer.rb', line 30

def get_action
  return @controller&.action_name&.to_sym
end

#get_controller_native_serializer_config ⇒ Object

Get a native serializer configuration from the controller.



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# File 'lib/rest_framework/serializers/native_serializer.rb', line 54

def get_controller_native_serializer_config
  return nil unless @controller

  if @many == true
    controller_serializer = @controller.try(:native_serializer_plural_config)
  elsif @many == false
    controller_serializer = @controller.try(:native_serializer_singular_config)
  end

  return controller_serializer || @controller.try(:native_serializer_config)
end

#get_local_native_serializer_config ⇒ Object

Get a locally defined native serializer configuration, if one is defined.



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# File 'lib/rest_framework/serializers/native_serializer.rb', line 35

def get_local_native_serializer_config
  action = self.get_action

  if action && self.action_config
    # Index action should use :list serializer config if :index is not provided.
    action = :list if action == :index && !self.action_config.key?(:index)

    return self.action_config[action] if self.action_config[action]
  end

  # No action_config, so try singular/plural config if explicitly instructed to via @many.
  return self.plural_config if @many == true && self.plural_config
  return self.singular_config if @many == false && self.singular_config

  # Lastly, try returning the default config, or singular/plural config in that order.
  return self.config || self.singular_config || self.plural_config
end

#get_raw_serializer_config ⇒ Object

Get the raw serializer config, prior to any adjustments from the request.

Use ‘deep_dup` on any class mutables (array, hash, etc) to avoid mutating class state.



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# File 'lib/rest_framework/serializers/native_serializer.rb', line 289

def get_raw_serializer_config
  # Return a locally defined serializer config if one is defined.
  if local_config = self.get_local_native_serializer_config
    return local_config.deep_dup
  end

  # Return a serializer config if one is defined on the controller.
  if serializer_config = self.get_controller_native_serializer_config
    return serializer_config.deep_dup
  end

  # If the config wasn't determined, build a serializer config from controller fields.
  if @model && fields = @controller&.get_fields
    return self._get_controller_serializer_config(fields.deep_dup)
  end

  # By default, pass an empty configuration, using the default Rails serializer.
  return {}
end

#get_serializer_config ⇒ Object

Get a configuration passable to ‘serializable_hash` for the object, filtered if required.



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# File 'lib/rest_framework/serializers/native_serializer.rb', line 310

def get_serializer_config
  return self.filter_from_request(self.get_raw_serializer_config)
end

#serialize(*args) ⇒ Object 



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# File 'lib/rest_framework/serializers/native_serializer.rb', line 327

def serialize(*args)
  config = self.get_serializer_config
  serializer_methods = config.delete(:serializer_methods)
  includes_map = config.delete(:includes_map)

  if @object.respond_to?(:to_ary)
    # Preload associations using `includes` to avoid N+1 queries. For now this also allows filter
    # backends to use associated data; perhaps it may be wise to have a system in place for
    # filters to preload their own associations?
    @object = @object.includes(*includes_map.values) if includes_map.present?

    return @object.map { |r| self._serialize(r, config, serializer_methods) }
  end

  return self._serialize(@object, config, serializer_methods)
end