BigDecimal string wrapping in JSON serialization can now be opted-out, fixes #6033

activesupport/CHANGELOG.md

@@ -32,6 +32,9 @@
 
 *    Unicode database updated to 6.1.0.
 
+*    Adds `encode_big_decimal_as_string` option to force JSON serialization of BigDecimals as numeric instead
+     of wrapping them in strings for safety.
+
 
 ## Rails 3.2.2 (March 1, 2012) ##
 

activesupport/lib/active_support/json/encoding.rb

@@ -17,6 +17,7 @@ module ActiveSupport
   class << self
     delegate :use_standard_json_time_format, :use_standard_json_time_format=,
       :escape_html_entities_in_json, :escape_html_entities_in_json=,
+      :encode_big_decimal_as_string, :encode_big_decimal_as_string=,
       :to => :'ActiveSupport::JSON::Encoding'
   end
 
@@ -104,6 +105,9 @@ module ActiveSupport
         # If true, use ISO 8601 format for dates and times. Otherwise, fall back to the Active Support legacy format.
         attr_accessor :use_standard_json_time_format
 
+        # If false, serializes BigDecimal objects as numeric instead of wrapping them in a string
+        attr_accessor :encode_big_decimal_as_string
+
         attr_accessor :escape_regex
         attr_reader :escape_html_entities_in_json
 
@@ -133,6 +137,7 @@ module ActiveSupport
 
       self.use_standard_json_time_format = true
       self.escape_html_entities_in_json  = false
+      self.encode_big_decimal_as_string  = true
     end
   end
 end
@@ -197,7 +202,15 @@ class BigDecimal
   # 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) finite? ? to_s : NilClass::AS_JSON end #:nodoc:
+  #
+  # Use ActiveSupport.use_standard_json_big_decimal_format = true to override this behaviour
+  def as_json(options = nil) #:nodoc:
+    if finite?
+      ActiveSupport.encode_big_decimal_as_string ? to_s : self
+    else
+      NilClass::AS_JSON
+    end
+  end
 end
 
 class Regexp

activesupport/test/json/encoding_test.rb

@@ -274,6 +274,17 @@ class TestJSONEncoding < ActiveSupport::TestCase
                  JSON.parse(json_string_and_date))
   end
 
+  def test_opt_out_big_decimal_string_serialization
+    big_decimal = BigDecimal('2.5')
+
+    begin
+      ActiveSupport.encode_big_decimal_as_string = false
+      assert_equal big_decimal.to_s, big_decimal.to_json
+    ensure
+      ActiveSupport.encode_big_decimal_as_string = true
+    end
+  end
+
   protected
 
     def object_keys(json_object)