1 files changed, 228 insertions, 0 deletions
diff --git a/activesupport/lib/active_support/core_ext/object/json.rb b/activesupport/lib/active_support/core_ext/object/json.rb
new file mode 100644
index 0000000000..416059d17b
--- /dev/null
+++ b/activesupport/lib/active_support/core_ext/object/json.rb
@@ -0,0 +1,228 @@
+# frozen_string_literal: true
+
+# Hack to load json gem first so we can overwrite its to_json.
+require "json"
+require "bigdecimal"
+require "uri/generic"
+require "pathname"
+require "active_support/core_ext/big_decimal/conversions" # for #to_s
+require "active_support/core_ext/hash/except"
+require "active_support/core_ext/hash/slice"
+require "active_support/core_ext/object/instance_variables"
+require "time"
+require "active_support/core_ext/time/conversions"
+require "active_support/core_ext/date_time/conversions"
+require "active_support/core_ext/date/conversions"
+
+#--
+# The JSON gem adds a few modules to Ruby core classes containing :to_json definition, overwriting
+# their default behavior. That said, we need to define the basic to_json method in all of them,
+# otherwise they will always use to_json gem implementation, which is backwards incompatible in
+# several cases (for instance, the JSON implementation for Hash does not work) with inheritance
+# and consequently classes as ActiveSupport::OrderedHash cannot be serialized to json.
+#
+# On the other hand, we should avoid conflict with ::JSON.{generate,dump}(obj). Unfortunately, the
+# JSON gem's encoder relies on its own to_json implementation to encode objects. Since it always
+# passes a ::JSON::State object as the only argument to to_json, we can detect that and forward the
+# calls to the original to_json method.
+#
+# It should be noted that when using ::JSON.{generate,dump} directly, ActiveSupport's encoder is
+# bypassed completely. This means that as_json won't be invoked and the JSON gem will simply
+# ignore any options it does not natively understand. This also means that ::JSON.{generate,dump}
+# should give exactly the same results with or without active support.
+
+module ActiveSupport
+  module ToJsonWithActiveSupportEncoder # :nodoc:
+    def to_json(options = nil)
+      if options.is_a?(::JSON::State)
+        # Called from JSON.{generate,dump}, forward it to JSON gem's to_json
+        super(options)
+      else
+        # to_json is being invoked directly, use ActiveSupport's encoder
+        ActiveSupport::JSON.encode(self, options)
+      end
+    end
+  end
+end
+
+[Object, Array, FalseClass, Float, Hash, Integer, NilClass, String, TrueClass, Enumerable].reverse_each do |klass|
+  klass.prepend(ActiveSupport::ToJsonWithActiveSupportEncoder)
+end
+
+class Object
+  def as_json(options = nil) #:nodoc:
+    if respond_to?(:to_hash)
+      to_hash.as_json(options)
+    else
+      instance_values.as_json(options)
+    end
+  end
+end
+
+class Struct #:nodoc:
+  def as_json(options = nil)
+    Hash[members.zip(values)].as_json(options)
+  end
+end
+
+class TrueClass
+  def as_json(options = nil) #:nodoc:
+    self
+  end
+end
+
+class FalseClass
+  def as_json(options = nil) #:nodoc:
+    self
+  end
+end
+
+class NilClass
+  def as_json(options = nil) #:nodoc:
+    self
+  end
+end
+
+class String
+  def as_json(options = nil) #:nodoc:
+    self
+  end
+end
+
+class Symbol
+  def as_json(options = nil) #:nodoc:
+    to_s
+  end
+end
+
+class Numeric
+  def as_json(options = nil) #:nodoc:
+    self
+  end
+end
+
+class Float
+  # Encoding Infinity or NaN to JSON should return "null". The default returns
+  # "Infinity" or "NaN" which are not valid JSON.
+  def as_json(options = nil) #:nodoc:
+    finite? ? self : nil
+  end
+end
+
+class BigDecimal
+  # A BigDecimal would be naturally represented as a JSON number. Most libraries,
+  # however, parse non-integer JSON numbers directly as floats. Clients using
+  # those libraries would get in general a wrong number and no way to recover
+  # other than manually inspecting the string with the JSON code itself.
+  #
+  # That's why a JSON string is returned. The JSON literal is not numeric, but
+  # if the other end knows by contract that the data is supposed to be a
+  # BigDecimal, it still has the chance to post-process the string and get the
+  # real value.
+  def as_json(options = nil) #:nodoc:
+    finite? ? to_s : nil
+  end
+end
+
+class Regexp
+  def as_json(options = nil) #:nodoc:
+    to_s
+  end
+end
+
+module Enumerable
+  def as_json(options = nil) #:nodoc:
+    to_a.as_json(options)
+  end
+end
+
+class IO
+  def as_json(options = nil) #:nodoc:
+    to_s
+  end
+end
+
+class Range
+  def as_json(options = nil) #:nodoc:
+    to_s
+  end
+end
+
+class Array
+  def as_json(options = nil) #:nodoc:
+    map { |v| options ? v.as_json(options.dup) : v.as_json }
+  end
+end
+
+class Hash
+  def as_json(options = nil) #:nodoc:
+    # create a subset of the hash by applying :only or :except
+    subset = if options
+      if attrs = options[:only]
+        slice(*Array(attrs))
+      elsif attrs = options[:except]
+        except(*Array(attrs))
+      else
+        self
+      end
+    else
+      self
+    end
+
+    Hash[subset.map { |k, v| [k.to_s, options ? v.as_json(options.dup) : v.as_json] }]
+  end
+end
+
+class Time
+  def as_json(options = nil) #:nodoc:
+    if ActiveSupport::JSON::Encoding.use_standard_json_time_format
+      xmlschema(ActiveSupport::JSON::Encoding.time_precision)
+    else
+      %(#{strftime("%Y/%m/%d %H:%M:%S")} #{formatted_offset(false)})
+    end
+  end
+end
+
+class Date
+  def as_json(options = nil) #:nodoc:
+    if ActiveSupport::JSON::Encoding.use_standard_json_time_format
+      strftime("%Y-%m-%d")
+    else
+      strftime("%Y/%m/%d")
+    end
+  end
+end
+
+class DateTime
+  def as_json(options = nil) #:nodoc:
+    if ActiveSupport::JSON::Encoding.use_standard_json_time_format
+      xmlschema(ActiveSupport::JSON::Encoding.time_precision)
+    else
+      strftime("%Y/%m/%d %H:%M:%S %z")
+    end
+  end
+end
+
+class URI::Generic #:nodoc:
+  def as_json(options = nil)
+    to_s
+  end
+end
+
+class Pathname #:nodoc:
+  def as_json(options = nil)
+    to_s
+  end
+end
+
+class Process::Status #:nodoc:
+  def as_json(options = nil)
+    { exitstatus: exitstatus, pid: pid }
+  end
+end
+
+class Exception
+  def as_json(options = nil)
+    to_s
+  end
+end