3 files changed, 30 insertions, 8 deletions
diff --git a/activerecord/lib/active_record/type/decimal.rb b/activerecord/lib/active_record/type/decimal.rb
index a9db51c6ba..d10778eeb6 100644
--- a/activerecord/lib/active_record/type/decimal.rb
+++ b/activerecord/lib/active_record/type/decimal.rb
@@ -14,10 +14,25 @@ module ActiveRecord
       private
 
       def cast_value(value)
-        if value.respond_to?(:to_d)
-          value.to_d
+        case value
+        when ::Float
+          BigDecimal(value, float_precision)
+        when ::Numeric, ::String
+          BigDecimal(value, precision.to_i)
         else
-          value.to_s.to_d
+          if value.respond_to?(:to_d)
+            value.to_d
+          else
+            cast_value(value.to_s)
+          end
+        end
+      end
+
+      def float_precision
+        if precision.to_i > ::Float::DIG + 1
+          ::Float::DIG + 1
+        else
+          precision.to_i
         end
       end
     end
diff --git a/activerecord/lib/active_record/type/serialized.rb b/activerecord/lib/active_record/type/serialized.rb
index 42bbed7103..abeea769c4 100644
--- a/activerecord/lib/active_record/type/serialized.rb
+++ b/activerecord/lib/active_record/type/serialized.rb
@@ -12,7 +12,7 @@ module ActiveRecord
       end
 
       def type_cast_from_database(value)
-        if is_default_value?(value)
+        if default_value?(value)
           value
         else
           coder.load(super)
@@ -21,7 +21,7 @@ module ActiveRecord
 
       def type_cast_for_database(value)
         return if value.nil?
-        unless is_default_value?(value)
+        unless default_value?(value)
           super coder.dump(value)
         end
       end
@@ -43,7 +43,7 @@ module ActiveRecord
 
       private
 
-      def is_default_value?(value)
+      def default_value?(value)
         value == coder.load(nil)
       end
     end
diff --git a/activerecord/lib/active_record/type/value.rb b/activerecord/lib/active_record/type/value.rb
index e0a783fb45..9456a4a56c 100644
--- a/activerecord/lib/active_record/type/value.rb
+++ b/activerecord/lib/active_record/type/value.rb
@@ -69,13 +69,20 @@ module ActiveRecord
       end
 
       # Determines whether the mutable value has been modified since it was
-      # read. Returns +false+ by default. This method should not need to be
-      # overriden directly. Types which return a mutable value should include
+      # read. Returns +false+ by default. This method should not be overridden
+      # directly. Types which return a mutable value should include
       # +Type::Mutable+, which will define this method.
       def changed_in_place?(*)
         false
       end
 
+      def ==(other)
+        self.class == other.class &&
+          precision == other.precision &&
+          scale == other.scale &&
+          limit == other.limit
+      end
+
       private
 
       def type_cast(value)