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).

Constant Summary collapse

EXTRACT_FROM_QUERY = 
->(p, controller) {
  return Set[] if p.blank?
  (
    controller.request&.query_parameters&.[](p).presence&.split(",")&.map { |x|
      x.strip.presence
    }&.compact || []
  ).to_set
}

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 18

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.klass if @many && @object.is_a?(ActiveRecord::Relation)
  @model ||= @object.first.class if @many &&
    @object.is_a?(Enumerable) &&
    @object.first.is_a?(ActiveRecord::Base)

  @model ||= @controller.class.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 404

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

.[]=(key, value) ⇒ Object 



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# File 'lib/rest_framework/serializers/native_serializer.rb', line 409

def self.[]=(key, value)
  @_nested_config ||= self.new.get_serializer_config
  @_nested_config[key] = value
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 393

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

#[]=(key, value) ⇒ Object 



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# File 'lib/rest_framework/serializers/native_serializer.rb', line 398

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

#_build_association_config(model, fields, nested) ⇒ Object

Recursively translate an association's fields into a serializable_hash config (only/methods/include). Columns go to only and plain methods to methods; a field that is itself an association is recursed into (as a nested include) only when it has its own entry in nested (the per-field config: map). Otherwise it falls through to a method and serializes as before (its full as_json), so deeper nesting is opt-in and never narrows the output.



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# File 'lib/rest_framework/serializers/native_serializer.rb', line 177

def _build_association_config(model, fields, nested)
  nested ||= {}
  only = []
  methods = []
  includes = {}

  fields.each do |sf|
    sf = sf.to_s
    sub_field_config = nested[sf.to_sym] || nested[sf]

    if sf.in?(model.column_names)
      only << sf
    elsif sub_field_config && (ref = model.reflect_on_association(sf.to_sym)) && !ref.polymorphic?
      sub_spec = RESTFramework::Utils.normalize_field_spec(sub_field_config[:fields])
      sub_fields = RESTFramework::Utils.resolve_field_names(
        sub_spec, RESTFramework::Utils.association_fields_for(ref)
      )
      includes[sf] = self._build_association_config(ref.klass, sub_fields, sub_spec[:config])
    elsif model.method_defined?(sf)
      methods << sf
    else
      only << sf
    end
  end

  config = { only: only, methods: methods }
  config[:include] = includes if includes.any?
  config
end

#_effective_association_fields(association_name, ref, field_config) ⇒ Object

The fields to serialize for association f, honoring a consumer's ?<prefix>.<f>.fields= request bounded by the allowlist. Only active when the feature is enabled.



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# File 'lib/rest_framework/serializers/native_serializer.rb', line 142

def _effective_association_fields(association_name, ref, field_config)
  default_fields = field_config[:fields]
  return default_fields unless @controller&.class&.enable_association_queries
  return default_fields if ref.polymorphic? # no single target class to bound the request

  requested = self._requested_association_fields(association_name)
  return default_fields if requested.blank?

  # The primary key is always kept so records stay identifiable. `_valid_association_field?` is
  # the last line of defense against leaking a non-serializable or nested-association field.
  allowed = (default_fields + (field_config[:requestable_fields] || [])).uniq
  valid = (requested & allowed).select { |sf| self._valid_association_field?(ref, sf) }
  (Array(ref.klass.primary_key).map(&:to_s) + valid).uniq
end

#_effective_association_limit(association_name, field_config) ⇒ Object

The record cap for a collection association (nil = unlimited). The default is applied even when the feature is off, so responses are always bounded. key? (not ||) reads the field_config override so an explicit nil there means unlimited/uncapped rather than falling back to the controller default.



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# File 'lib/rest_framework/serializers/native_serializer.rb', line 105

def _effective_association_limit(association_name, field_config)
  klass = @controller&.class

  default = field_config.key?(:limit) ? field_config[:limit] : klass&.association_limit
  return default unless klass&.enable_association_queries

  requested = self._requested_association_limit(association_name)
  return default if requested.nil?

  max = field_config.key?(:limit_max) ? field_config[:limit_max] : klass.association_limit_max

  # `all` means "as many as allowed" — the cap, or unlimited when the cap is `nil`.
  return max if requested == :all

  max ? [ requested, max ].min : requested
end

#_get_controller_serializer_config ⇒ 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 208

def _get_controller_serializer_config
  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

  self.fields.each do |f|
    field_config = @controller.class.field_configuration[f]
    next if field_config[:write_only]

    if f.in?(column_names)
      columns << f
    elsif ref = reflections[f]
      # A polymorphic `belongs_to` has no single target class to introspect, so serialize it via a
      # method that emits the `type` (from the `*_type` column) and id, a label when the target
      # has one, and any other configured `fields` the target responds to. Consumer-driven
      # field/limit requests don't apply (they need one target class; see the serializer method).
      if ref.polymorphic?
        foreign_type = ref.foreign_type
        fields = field_config[:fields]
        serializer_methods[f] = f
        includes_map[f] = f.to_sym
        self.define_singleton_method(f) do |record|
          next nil unless target = record.send(f)

          RESTFramework::Utils.serialize_polymorphic(target, record.send(foreign_type), fields)
        end

        next
      end

      effective_fields = self._effective_association_fields(f, ref, field_config)
      sub_config = self._build_association_config(
        ref.klass, effective_fields, field_config[:field_config]
      )

      # Apply certain rules regarding collection associations.
      if ref.collection?
        # A finite limit needs a per-record `.limit` query, since eager `includes` can't cap rows
        # per parent; an unlimited (`nil`) association falls through to `includes` preloading.
        if limit = self._effective_association_limit(f, field_config)
          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.class.include_association_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.class.include_association_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 @controller.class.enable_action_text && 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 @controller.class.enable_active_storage && 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|
          attached = record.send(f)
          next attached.attachment ? {
            filename: attached.filename,
            signed_id: attached.signed_id,
            url: attached.url,
          } : nil
        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 { |a|
            {
              filename: a.filename,
              signed_id: a.signed_id,
              url: a.url,
            }
          }
        end
      end
    elsif @model.method_defined?(f)
      methods << f
    else
      # Assume anything else is a virtual column.
      columns << f
    end
  end

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

#_requested_association_fields(association_name) ⇒ Object

Only a plain scalar string is honored, so a nested-hash/array param can't reach where/split.



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# File 'lib/rest_framework/serializers/native_serializer.rb', line 158

def _requested_association_fields(association_name)
  return nil unless prefix = @controller.class.association_query_prefix.presence

  raw = @controller.request&.query_parameters&.[]("#{prefix}.#{association_name}.fields")
  return nil unless raw.is_a?(String)

  raw.split(",").map { |x| x.strip.presence }.compact
end

#_requested_association_limit(association_name) ⇒ Object

all, none, and 0 all mean "no limit" — 0 is free to reuse as a sentinel since an association is dropped via except, not limit=0. Anything else must be a plain positive integer, so a nested/array param or junk can't drive the query.



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# File 'lib/rest_framework/serializers/native_serializer.rb', line 125

def _requested_association_limit(association_name)
  return nil unless prefix = @controller.class.association_query_prefix.presence

  raw = @controller.request&.query_parameters&.[]("#{prefix}.#{association_name}.limit")
  return nil unless raw.is_a?(String)

  raw = raw.strip
  return :all if raw.in?(%w[all none])
  return nil unless raw.match?(/\A\d+\z/)

  # The regex guarantees a non-negative integer, so anything but zero is a positive limit.
  limit = raw.to_i
  limit.zero? ? :all : limit
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 363

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.
  record.serializable_hash(config).merge(
    serializer_methods&.map { |m, k| [ k.to_sym, self.send(m, record) ] }.to_h,
  )
end

#_valid_association_field?(ref, field) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/rest_framework/serializers/native_serializer.rb', line 167

def _valid_association_field?(ref, field)
  field.in?(ref.klass.column_names) ||
    (ref.klass.method_defined?(field) && !ref.klass.reflect_on_association(field.to_sym))
end

#action ⇒ Object 



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# File 'lib/rest_framework/serializers/native_serializer.rb', line 39

def action
  @action ||= @controller&.action_name&.to_sym
end

#fields ⇒ Object 



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# File 'lib/rest_framework/serializers/native_serializer.rb', line 43

def fields
  return @fields if defined?(@fields)
  return nil unless base_fields = @controller&.get_fields

  only_param = @controller.class.only_query_param
  except_param = @controller.class.except_query_param
  include_param = @controller.class.include_query_param
  exclude_param = @controller.class.exclude_query_param

  only = EXTRACT_FROM_QUERY.call(only_param, @controller)
  except = EXTRACT_FROM_QUERY.call(except_param, @controller)
  include = EXTRACT_FROM_QUERY.call(include_param, @controller)
  exclude = EXTRACT_FROM_QUERY.call(exclude_param, @controller)

  field_configuration = @controller.class.field_configuration
  @fields = base_fields.select do |f|
    cfg = field_configuration[f]

    # We never serialize write-only fields.
    next false if cfg[:write_only]

    # We never serialize `hidden_from_index` fields for collections as this is a performance
    # option.
    next false if cfg[:hidden_from_index] && @many

    # Explicitly excluded fields should never be serialized.
    next false if f.in?(except) || f.in?(exclude)

    # Hidden fields must be in `only` or `include` to be serialized; for non-hidden fields, either
    # `only` must be empty, or the field must be in `only` or `include`.
    if cfg[:hidden]
      next true if f.in?(only) || f.in?(include)
    elsif only.empty? || f.in?(only) || f.in?(include)
      next true
    end

    next false
  end

  @fields
end

#get_local_native_serializer_config ⇒ Object 



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# File 'lib/rest_framework/serializers/native_serializer.rb', line 85

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

    return cfg[action] if cfg[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.
  self.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 342

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

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

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

#get_serializer_config ⇒ Object

Get a configuration passable to serializable_hash for the object.



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# File 'lib/rest_framework/serializers/native_serializer.rb', line 358

def get_serializer_config
  self.get_raw_serializer_config
end

#serialize(*args) ⇒ Object 



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# File 'lib/rest_framework/serializers/native_serializer.rb', line 375

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

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