module FastSerializer::Serializer

Models can include this module to define themselves as serializers. A serializer is used to wrap an object and output a hash version of that object suitable for serialization to JSON or other formats.

To define what fields to serialize on the wrapped object, the serializer class must call the serialize class method:

class PersonSerializer
  include FastSerializer::Serializer
  serialize :id, :name
end

This sample serializer will output an object as a hash with keys {:id, :name}. The values for each field is gotten by calling the corresponding method on the serializer object. By default, each serialized field will automatically define a method that simply delegates to the wrapped object. So if you need provide special handling for a field or serialize a virtual field that doesn't exist on the parent object, you just need to implement the method on the serializer.

class PersonSerializer
  include FastSerializer::Serializer
  serialize :id, :name

  def name
    "#{object.first_name} #{object.last_name}"
  end
end

Serializers can implement their own options for controlling details about how to serialize the object.

class PersonSerializer
  include FastSerializer::Serializer
  serialize :id, :name

  def name
    if option(:last_first)
      "#{object.last_name}, #{object.first_name}"
    else
      "#{object.first_name} #{object.last_name}"
    end
  end
end

serializer = PersonSerializer.new(person, :last_first => true)

All serializers will honor options for :include (include optional fields), :exclude (exclude fields).

Serializer can also be specified as cacheable. Cacheable serializer will store and fetch the serialized value from a cache. In order to user caching you must set the cache implementation. This can either be done on a global level (FastSerializer.cache) class level, or instance level (:cache option). Then you can specify serializers to be cacheable. This can be done on a class level with the cacheable directive or on an instance level with the :cacheable option. A time to live can also be set at the same levels using cache_ttl.

Serializers are designed to be reusable and must never have any internal state associated with them. Calling as_json on a serializer multiple times must always return the same value.

Serializing a nil object will result in nil rather than an empty hash.

Attributes

object[R]

Return the wrapped object that is being serialized.

options[R]

Return the options hash (if any) that specified optional details about how to serialize the object.

Public Class Methods

included(base) click to toggle source
# File lib/fast_serializer/serializer.rb, line 61
def self.included(base)
  base.extend(ClassMethods)
  base.extend(ArrayHelper) unless base.is_a?(FastSerializer::ArraySerializer)
end
new(object, options = nil) click to toggle source

Create a new serializer for the specified object.

Options can be passed in to control how the object is serialized. Options supported by all Serializers:

  • :include - Field or array of optional field names that should be included in the serialized object.

  • :exclude - Field or array of field names that should be excluded from the serialized object.

  • :cacheable - Override the cacheable behavior set on the class.

  • :cache_ttl - Override the cache ttl set on the class.

  • :cache - Override the cache implementation set on the class.

# File lib/fast_serializer/serializer.rb, line 285
def initialize(object, options = nil)
  @object = object
  @options = options
  @cache = options[:cache] if options
  if @cache && defined?(ActiveSupport::Cache::Store) && cache.is_a?(ActiveSupport::Cache::Store)
    @cache = Cache::ActiveSupportCache.new(@cache)
  end
  @_serialized = nil
end

Public Instance Methods

as_json(*args) click to toggle source

Serialize the wrapped object into a format suitable for passing to a JSON parser.

# File lib/fast_serializer/serializer.rb, line 296
def as_json(*args)
  return nil unless object
  unless @_serialized
    @_serialized = (cacheable? ? load_from_cache : load_hash).freeze
  end
  @_serialized
end
Also aliased as: to_hash, to_h
cache() click to toggle source

Return the cache implementation where this serializer can be stored.

# File lib/fast_serializer/serializer.rb, line 331
def cache
  @cache || self.class.cache
end
cache_key() click to toggle source

Returns a array of the elements that make this serializer unique. The key is an array made up of the serializer class name, wrapped object, and serialization options hash.

# File lib/fast_serializer/serializer.rb, line 343
def cache_key
  object_cache_key = (object.respond_to?(:cache_key) ? object.cache_key : object)
  [self.class.name, object_cache_key, options_cache_key(options)]
end
cache_ttl() click to toggle source

Return the time to live in seconds this serializer can be cached for.

# File lib/fast_serializer/serializer.rb, line 336
def cache_ttl
  option(:cache_ttl) || self.class.cache_ttl
end
cacheable?() click to toggle source

Return true if this serializer is cacheable.

# File lib/fast_serializer/serializer.rb, line 326
def cacheable?
  option(:cacheable) || self.class.cacheable?
end
option(name) click to toggle source

Fetch the specified option from the options hash.

# File lib/fast_serializer/serializer.rb, line 317
def option(name)
  @options[name] if @options
end
scope() click to toggle source
# File lib/fast_serializer/serializer.rb, line 321
def scope
  option(:scope)
end
to_h(*args)
Alias for: as_json
to_hash(*args)
Alias for: as_json
to_json(options = {}) click to toggle source

Convert the wrapped object to JSON format.

# File lib/fast_serializer/serializer.rb, line 308
def to_json(options = {})
  if defined?(MultiJson)
    MultiJson.dump(as_json, options)
  else
    JSON.dump(as_json)
  end
end