Merge pull request #30941 from toptal/introduce-custom-serializers-to-activejob-arguments

Introduce custom serializers to ActiveJob arguments

16 files changed, 454 insertions, 14 deletions

diff --git a/activejob/CHANGELOG.md b/activejob/CHANGELOG.md
index ec99b5d975..e4768eb3d4 100644
--- a/activejob/CHANGELOG.md
+++ b/activejob/CHANGELOG.md
@@ -1,3 +1,6 @@
+*   Add support to define custom argument serializers.
+
+    *Evgenii Pecherkin*, *Rafael Mendonça França*
 
 
 Please check [5-2-stable](https://github.com/rails/rails/blob/5-2-stable/activejob/CHANGELOG.md) for previous changes.
diff --git a/activejob/lib/active_job.rb b/activejob/lib/active_job.rb
index 626abaa767..01fab4d918 100644
--- a/activejob/lib/active_job.rb
+++ b/activejob/lib/active_job.rb
@@ -33,6 +33,7 @@ module ActiveJob
 
   autoload :Base
   autoload :QueueAdapters
+  autoload :Serializers
   autoload :ConfiguredJob
   autoload :TestCase
   autoload :TestHelper
diff --git a/activejob/lib/active_job/arguments.rb b/activejob/lib/active_job/arguments.rb
index de11e7fcb1..e6ada163e8 100644
--- a/activejob/lib/active_job/arguments.rb
+++ b/activejob/lib/active_job/arguments.rb
@@ -44,13 +44,24 @@ module ActiveJob
     end
 
     private
+
       # :nodoc:
       GLOBALID_KEY = "_aj_globalid".freeze
       # :nodoc:
       SYMBOL_KEYS_KEY = "_aj_symbol_keys".freeze
       # :nodoc:
       WITH_INDIFFERENT_ACCESS_KEY = "_aj_hash_with_indifferent_access".freeze
-      private_constant :GLOBALID_KEY, :SYMBOL_KEYS_KEY, :WITH_INDIFFERENT_ACCESS_KEY
+      # :nodoc:
+      OBJECT_SERIALIZER_KEY = "_aj_serialized"
+
+      # :nodoc:
+      RESERVED_KEYS = [
+        GLOBALID_KEY, GLOBALID_KEY.to_sym,
+        SYMBOL_KEYS_KEY, SYMBOL_KEYS_KEY.to_sym,
+        OBJECT_SERIALIZER_KEY, OBJECT_SERIALIZER_KEY.to_sym,
+        WITH_INDIFFERENT_ACCESS_KEY, WITH_INDIFFERENT_ACCESS_KEY.to_sym,
+      ]
+      private_constant :RESERVED_KEYS
 
       def serialize_argument(argument)
         case argument
@@ -70,7 +81,7 @@ module ActiveJob
           result[SYMBOL_KEYS_KEY] = symbol_keys
           result
         else
-          raise SerializationError.new("Unsupported argument type: #{argument.class.name}")
+          Serializers.serialize(argument)
         end
       end
 
@@ -85,6 +96,8 @@ module ActiveJob
         when Hash
           if serialized_global_id?(argument)
             deserialize_global_id argument
+          elsif custom_serialized?(argument)
+            Serializers.deserialize(argument)
           else
             deserialize_hash(argument)
           end
@@ -101,6 +114,10 @@ module ActiveJob
         GlobalID::Locator.locate hash[GLOBALID_KEY]
       end
 
+      def custom_serialized?(hash)
+        hash.key?(OBJECT_SERIALIZER_KEY)
+      end
+
       def serialize_hash(argument)
         argument.each_with_object({}) do |(key, value), hash|
           hash[serialize_hash_key(key)] = serialize_argument(value)
@@ -117,14 +134,6 @@ module ActiveJob
         result
       end
 
-      # :nodoc:
-      RESERVED_KEYS = [
-        GLOBALID_KEY, GLOBALID_KEY.to_sym,
-        SYMBOL_KEYS_KEY, SYMBOL_KEYS_KEY.to_sym,
-        WITH_INDIFFERENT_ACCESS_KEY, WITH_INDIFFERENT_ACCESS_KEY.to_sym,
-      ]
-      private_constant :RESERVED_KEYS
-
       def serialize_hash_key(key)
         case key
         when *RESERVED_KEYS
diff --git a/activejob/lib/active_job/base.rb b/activejob/lib/active_job/base.rb
index ae112abb2c..6194f89956 100644
--- a/activejob/lib/active_job/base.rb
+++ b/activejob/lib/active_job/base.rb
@@ -59,6 +59,7 @@ module ActiveJob #:nodoc:
   # * SerializationError - Error class for serialization errors.
   class Base
     include Core
+    include Serializers
     include QueueAdapter
     include QueueName
     include QueuePriority
diff --git a/activejob/lib/active_job/railtie.rb b/activejob/lib/active_job/railtie.rb
index 7b0742a6d2..427ad1e3af 100644
--- a/activejob/lib/active_job/railtie.rb
+++ b/activejob/lib/active_job/railtie.rb
@@ -7,11 +7,17 @@ module ActiveJob
   # = Active Job Railtie
   class Railtie < Rails::Railtie # :nodoc:
     config.active_job = ActiveSupport::OrderedOptions.new
+    config.active_job.custom_serializers = []
 
     initializer "active_job.logger" do
       ActiveSupport.on_load(:active_job) { self.logger = ::Rails.logger }
     end
 
+    initializer "active_job.custom_serializers" do |app|
+      custom_serializers = app.config.active_job.delete(:custom_serializers)
+      ActiveJob::Serializers.add_serializers custom_serializers
+    end
+
     initializer "active_job.set_configs" do |app|
       options = app.config.active_job
       options.queue_adapter ||= :async
diff --git a/activejob/lib/active_job/serializers.rb b/activejob/lib/active_job/serializers.rb
new file mode 100644
index 0000000000..d9a130fa73
--- /dev/null
+++ b/activejob/lib/active_job/serializers.rb
@@ -0,0 +1,62 @@
+# frozen_string_literal: true
+
+require "set"
+
+module ActiveJob
+  # The <tt>ActiveJob::Serializers</tt> module is used to store a list of known serializers
+  # and to add new ones. It also has helpers to serialize/deserialize objects
+  module Serializers
+    extend ActiveSupport::Autoload
+    extend ActiveSupport::Concern
+
+    autoload :ObjectSerializer
+    autoload :SymbolSerializer
+    autoload :DurationSerializer
+    autoload :DateSerializer
+    autoload :TimeSerializer
+    autoload :DateTimeSerializer
+
+    mattr_accessor :_additional_serializers
+    self._additional_serializers = Set.new
+
+    class << self
+      # Returns serialized representative of the passed object.
+      # Will look up through all known serializers.
+      # Raises `ActiveJob::SerializationError` if it can't find a proper serializer.
+      def serialize(argument)
+        serializer = serializers.detect { |s| s.serialize?(argument) }
+        raise SerializationError.new("Unsupported argument type: #{argument.class.name}") unless serializer
+        serializer.serialize(argument)
+      end
+
+      # Returns deserialized object.
+      # Will look up through all known serializers.
+      # If no serializers found will raise `ArgumentError`
+      def deserialize(argument)
+        serializer_name = argument[Arguments::OBJECT_SERIALIZER_KEY]
+        raise ArgumentError, "Serializer name is not present in the argument: #{argument.inspect}" unless serializer_name
+
+        serializer = serializer_name.safe_constantize
+        raise ArgumentError, "Serializer #{serializer_name} is not know" unless serializer
+
+        serializer.deserialize(argument)
+      end
+
+      # Returns list of known serializers
+      def serializers
+        self._additional_serializers
+      end
+
+      # Adds a new serializer to a list of known serializers
+      def add_serializers(*new_serializers)
+        self._additional_serializers += new_serializers
+      end
+    end
+
+    add_serializers SymbolSerializer,
+      DurationSerializer,
+      DateTimeSerializer,
+      DateSerializer,
+      TimeSerializer
+  end
+end
diff --git a/activejob/lib/active_job/serializers/date_serializer.rb b/activejob/lib/active_job/serializers/date_serializer.rb
new file mode 100644
index 0000000000..e995d30faa
--- /dev/null
+++ b/activejob/lib/active_job/serializers/date_serializer.rb
@@ -0,0 +1,21 @@
+# frozen_string_literal: true
+
+module ActiveJob
+  module Serializers
+    class DateSerializer < ObjectSerializer # :nodoc:
+      def serialize(date)
+        super("value" => date.iso8601)
+      end
+
+      def deserialize(hash)
+        Date.iso8601(hash["value"])
+      end
+
+      private
+
+        def klass
+          Date
+        end
+    end
+  end
+end
diff --git a/activejob/lib/active_job/serializers/date_time_serializer.rb b/activejob/lib/active_job/serializers/date_time_serializer.rb
new file mode 100644
index 0000000000..fe780a1978
--- /dev/null
+++ b/activejob/lib/active_job/serializers/date_time_serializer.rb
@@ -0,0 +1,21 @@
+# frozen_string_literal: true
+
+module ActiveJob
+  module Serializers
+    class DateTimeSerializer < ObjectSerializer # :nodoc:
+      def serialize(time)
+        super("value" => time.iso8601)
+      end
+
+      def deserialize(hash)
+        DateTime.iso8601(hash["value"])
+      end
+
+      private
+
+        def klass
+          DateTime
+        end
+    end
+  end
+end
diff --git a/activejob/lib/active_job/serializers/duration_serializer.rb b/activejob/lib/active_job/serializers/duration_serializer.rb
new file mode 100644
index 0000000000..715fe27a5c
--- /dev/null
+++ b/activejob/lib/active_job/serializers/duration_serializer.rb
@@ -0,0 +1,24 @@
+# frozen_string_literal: true
+
+module ActiveJob
+  module Serializers
+    class DurationSerializer < ObjectSerializer # :nodoc:
+      def serialize(duration)
+        super("value" => duration.value, "parts" => Arguments.serialize(duration.parts))
+      end
+
+      def deserialize(hash)
+        value = hash["value"]
+        parts = Arguments.deserialize(hash["parts"])
+
+        klass.new(value, parts)
+      end
+
+      private
+
+        def klass
+          ActiveSupport::Duration
+        end
+    end
+  end
+end
diff --git a/activejob/lib/active_job/serializers/object_serializer.rb b/activejob/lib/active_job/serializers/object_serializer.rb
new file mode 100644
index 0000000000..9f59e8236f
--- /dev/null
+++ b/activejob/lib/active_job/serializers/object_serializer.rb
@@ -0,0 +1,54 @@
+# frozen_string_literal: true
+
+module ActiveJob
+  module Serializers
+    # Base class for serializing and deserializing custom times.
+    #
+    # Example
+    #
+    #     class MoneySerializer < ActiveJob::Serializers::ObjectSerializer
+    #       def serialize(money)
+    #         super("cents" => money.cents, "currency" => money.currency)
+    #       end
+    #
+    #       def deserialize(hash)
+    #         Money.new(hash["cents"], hash["currency"])
+    #       end
+    #
+    #       private
+    #
+    #         def klass
+    #           Money
+    #         end
+    #     end
+    class ObjectSerializer
+      include Singleton
+
+      class << self
+        delegate :serialize?, :serialize, :deserialize, to: :instance
+      end
+
+      # Determines if an argument should be serialized by a serializer.
+      def serialize?(argument)
+        argument.is_a?(klass)
+      end
+
+      # Serializes an argument to a JSON primitive type.
+      def serialize(hash)
+        { Arguments::OBJECT_SERIALIZER_KEY => self.class.name }.merge!(hash)
+      end
+
+      # Deserilizes an argument form a JSON primiteve type.
+      def deserialize(_argument)
+        raise NotImplementedError
+      end
+
+      protected
+
+        # The class of the object that will be serialized.
+        def klass
+          raise NotImplementedError
+        end
+    end
+  end
+end
diff --git a/activejob/lib/active_job/serializers/symbol_serializer.rb b/activejob/lib/active_job/serializers/symbol_serializer.rb
new file mode 100644
index 0000000000..7e1f9553a2
--- /dev/null
+++ b/activejob/lib/active_job/serializers/symbol_serializer.rb
@@ -0,0 +1,21 @@
+# frozen_string_literal: true
+
+module ActiveJob
+  module Serializers
+    class SymbolSerializer < ObjectSerializer # :nodoc:
+      def serialize(argument)
+        super("value" => argument.to_s)
+      end
+
+      def deserialize(argument)
+        argument["value"].to_sym
+      end
+
+      private
+
+        def klass
+          Symbol
+        end
+    end
+  end
+end
diff --git a/activejob/lib/active_job/serializers/time_serializer.rb b/activejob/lib/active_job/serializers/time_serializer.rb
new file mode 100644
index 0000000000..fe20772f35
--- /dev/null
+++ b/activejob/lib/active_job/serializers/time_serializer.rb
@@ -0,0 +1,21 @@
+# frozen_string_literal: true
+
+module ActiveJob
+  module Serializers
+    class TimeSerializer < ObjectSerializer # :nodoc:
+      def serialize(time)
+        super("value" => time.iso8601)
+      end
+
+      def deserialize(hash)
+        Time.iso8601(hash["value"])
+      end
+
+      private
+
+        def klass
+          Time
+        end
+    end
+  end
+end
diff --git a/activejob/test/cases/argument_serialization_test.rb b/activejob/test/cases/argument_serialization_test.rb
index 7e7f854da0..ff6ac6fc43 100644
--- a/activejob/test/cases/argument_serialization_test.rb
+++ b/activejob/test/cases/argument_serialization_test.rb
@@ -12,7 +12,10 @@ class ArgumentSerializationTest < ActiveSupport::TestCase
   end
 
   [ nil, 1, 1.0, 1_000_000_000_000_000_000_000,
-    "a", true, false, BigDecimal(5),
+    "a", true, false, BigDecimal.new(5),
+    :a, 1.day, Date.new(2001, 2, 3), Time.new(2002, 10, 31, 2, 2, 2, "+02:00"),
+    DateTime.new(2001, 2, 3, 4, 5, 6, "+03:00"),
+    ActiveSupport::TimeWithZone.new(Time.utc(1999, 12, 31, 23, 59, 59), ActiveSupport::TimeZone["UTC"]),
     [ 1, "a" ],
     { "a" => 1 }
   ].each do |arg|
@@ -21,7 +24,7 @@ class ArgumentSerializationTest < ActiveSupport::TestCase
     end
   end
 
-  [ :a, Object.new, self, Person.find("5").to_gid ].each do |arg|
+  [ Object.new, self, Person.find("5").to_gid ].each do |arg|
     test "does not serialize #{arg.class}" do
       assert_raises ActiveJob::SerializationError do
         ActiveJob::Arguments.serialize [ arg ]
@@ -46,6 +49,49 @@ class ArgumentSerializationTest < ActiveSupport::TestCase
     assert_arguments_roundtrip([a: 1, "b" => 2])
   end
 
+  test "serialize a hash" do
+    symbol_key = { a: 1 }
+    string_key = { "a" => 1 }
+    indifferent_access = { a: 1 }.with_indifferent_access
+
+    assert_equal(
+      { "a" => 1, "_aj_symbol_keys" => ["a"] },
+      ActiveJob::Arguments.serialize([symbol_key]).first
+    )
+    assert_equal(
+      { "a" => 1, "_aj_symbol_keys" => [] },
+      ActiveJob::Arguments.serialize([string_key]).first
+    )
+    assert_equal(
+      { "a" => 1, "_aj_hash_with_indifferent_access" => true },
+      ActiveJob::Arguments.serialize([indifferent_access]).first
+    )
+  end
+
+  test "deserialize a hash" do
+    symbol_key = { "a" => 1, "_aj_symbol_keys" => ["a"] }
+    string_key = { "a" => 1, "_aj_symbol_keys" => [] }
+    another_string_key = { "a" => 1 }
+    indifferent_access = { "a" => 1, "_aj_hash_with_indifferent_access" => true }
+
+    assert_equal(
+      { a: 1 },
+      ActiveJob::Arguments.deserialize([symbol_key]).first
+    )
+    assert_equal(
+      { "a" => 1 },
+      ActiveJob::Arguments.deserialize([string_key]).first
+    )
+    assert_equal(
+      { "a" => 1 },
+      ActiveJob::Arguments.deserialize([another_string_key]).first
+    )
+    assert_equal(
+      { "a" => 1 },
+      ActiveJob::Arguments.deserialize([indifferent_access]).first
+    )
+  end
+
   test "should maintain hash with indifferent access" do
     symbol_key = { a: 1 }
     string_key = { "a" => 1 }
diff --git a/activejob/test/cases/serializers_test.rb b/activejob/test/cases/serializers_test.rb
new file mode 100644
index 0000000000..a86f168d03
--- /dev/null
+++ b/activejob/test/cases/serializers_test.rb
@@ -0,0 +1,98 @@
+# frozen_string_literal: true
+
+require "helper"
+require "active_job/serializers"
+
+class SerializersTest < ActiveSupport::TestCase
+  class DummyValueObject
+    attr_accessor :value
+
+    def initialize(value)
+      @value = value
+    end
+
+    def ==(other)
+      self.value == other.value
+    end
+  end
+
+  class DummySerializer < ActiveJob::Serializers::ObjectSerializer
+    def serialize(object)
+      super({ "value" => object.value })
+    end
+
+    def deserialize(hash)
+      DummyValueObject.new(hash["value"])
+    end
+
+    private
+
+      def klass
+        DummyValueObject
+      end
+  end
+
+  setup do
+    @value_object = DummyValueObject.new 123
+    @original_serializers = ActiveJob::Serializers.serializers
+  end
+
+  teardown do
+    ActiveJob::Serializers._additional_serializers = @original_serializers
+  end
+
+  test "can't serialize unknown object" do
+    assert_raises ActiveJob::SerializationError do
+      ActiveJob::Serializers.serialize @value_object
+    end
+  end
+
+  test "will serialize objects with serializers registered" do
+    ActiveJob::Serializers.add_serializers DummySerializer
+
+    assert_equal(
+      { "_aj_serialized" => "SerializersTest::DummySerializer", "value" => 123 },
+      ActiveJob::Serializers.serialize(@value_object)
+    )
+  end
+
+  test "won't deserialize unknown hash" do
+    hash = { "_dummy_serializer" => 123, "_aj_symbol_keys" => [] }
+    error = assert_raises(ArgumentError) do
+      ActiveJob::Serializers.deserialize(hash)
+    end
+    assert_equal(
+      'Serializer name is not present in the argument: {"_dummy_serializer"=>123, "_aj_symbol_keys"=>[]}',
+      error.message
+    )
+  end
+
+  test "won't deserialize unknown serializer" do
+    hash = { "_aj_serialized" => "DoNotExist", "value" => 123 }
+    error = assert_raises(ArgumentError) do
+      ActiveJob::Serializers.deserialize(hash)
+    end
+    assert_equal(
+      "Serializer DoNotExist is not know",
+      error.message
+    )
+  end
+
+  test "will deserialize know serialized objects" do
+    ActiveJob::Serializers.add_serializers DummySerializer
+    hash = { "_aj_serialized" => "SerializersTest::DummySerializer", "value" => 123 }
+    assert_equal DummyValueObject.new(123), ActiveJob::Serializers.deserialize(hash)
+  end
+
+  test "adds new serializer" do
+    ActiveJob::Serializers.add_serializers DummySerializer
+    assert ActiveJob::Serializers.serializers.include?(DummySerializer)
+  end
+
+  test "can't add serializer with the same key twice" do
+    ActiveJob::Serializers.add_serializers DummySerializer
+    assert_no_difference(-> { ActiveJob::Serializers.serializers.size }) do
+      ActiveJob::Serializers.add_serializers DummySerializer
+    end
+  end
+end
diff --git a/guides/source/active_job_basics.md b/guides/source/active_job_basics.md
index 914ef2c327..92a04c585f 100644
--- a/guides/source/active_job_basics.md
+++ b/guides/source/active_job_basics.md
@@ -339,8 +339,23 @@ UserMailer.welcome(@user).deliver_later # Email will be localized to Esperanto.
 ```
 
 
-GlobalID
---------
+Supported types for arguments
+----------------------------
+
+ActiveJob supports the following types of arguments by default:
+
+  - Basic types (`NilClass`, `String`, `Integer`, `Fixnum`, `Bignum`, `Float`, `BigDecimal`, `TrueClass`, `FalseClass`)
+  - `Symbol
+  - `ActiveSupport::Duration`
+  - `Date`
+  - `Time`
+  - `DateTime`
+  - `ActiveSupport::TimeWithZone`
+  - `Hash`. Keys should be of `String` or `Symbol` type
+  - `ActiveSupport::HashWithIndifferentAccess`
+  - `Array`
+
+### GlobalID
 
 Active Job supports GlobalID for parameters. This makes it possible to pass live
 Active Record objects to your job instead of class/id pairs, which you then have
@@ -368,6 +383,41 @@ end
 This works with any class that mixes in `GlobalID::Identification`, which
 by default has been mixed into Active Record classes.
 
+### Serializers
+
+You can extend list of supported types for arguments. You just need to define your own serializer.
+
+```ruby
+class MoneySerializer < ActiveJob::Serializers::ObjectSerializer
+    # Check if this object should be serialized using this serializer.
+    def serialize?(argument)
+      argument.is_a? Money
+    end
+
+    # Convert an object to a simpler representative using supported object types.
+    # The recommended representative is a Hash with a specific key. Keys can be of basic types only.
+    # You should call `super` to add the custom serializer type to the hash
+    def serialize(object)
+      super(
+        "cents" => object.cents,
+        "currency" => object.currency
+      )
+    end
+
+    # Convert serialized value into a proper object
+    def deserialize(hash)
+      Money.new hash["cents"], hash["currency"]
+    end
+  end
+end
+```
+
+And now you just need to add this serializer to a list:
+
+```ruby
+Rails.application.config.active_job.custom_serializers << MySpecialSerializer
+```
+
 
 Exceptions
 ----------
diff --git a/guides/source/configuring.md b/guides/source/configuring.md
index b0f39e7ab5..fd747c1686 100644
--- a/guides/source/configuring.md
+++ b/guides/source/configuring.md
@@ -741,6 +741,8 @@ There are a few configuration options available in Active Support:
 
 * `config.active_job.logger` accepts a logger conforming to the interface of Log4r or the default Ruby Logger class, which is then used to log information from Active Job. You can retrieve this logger by calling `logger` on either an Active Job class or an Active Job instance. Set to `nil` to disable logging.
 
+* `config.active_job.custom_serializers` allows to set custom argument serializers. Defaults to `[]`.
+
 ### Configuring Action Cable
 
 * `config.action_cable.url` accepts a string for the URL for where