3 files changed, 14 insertions, 2 deletions
diff --git a/activerecord/CHANGELOG.md b/activerecord/CHANGELOG.md
index c95e80755d..81ff2923ce 100644
--- a/activerecord/CHANGELOG.md
+++ b/activerecord/CHANGELOG.md
@@ -1,3 +1,9 @@
+*   `update_all` will now pass its values to `Type#cast` before passing them to
+    `Type#serialize`. This means that `update_all(foo: 'true')` will properly
+    persist a boolean.
+
+    *Sean Griffin*
+
 *   Add new error class `StatementTimeout` which will be raised
     when statement timeout exceeded.
 
diff --git a/activerecord/lib/active_record/sanitization.rb b/activerecord/lib/active_record/sanitization.rb
index 1c3099f55c..90cc3373fb 100644
--- a/activerecord/lib/active_record/sanitization.rb
+++ b/activerecord/lib/active_record/sanitization.rb
@@ -110,7 +110,8 @@ module ActiveRecord
         def sanitize_sql_hash_for_assignment(attrs, table) # :doc:
           c = connection
           attrs.map do |attr, value|
-            value = type_for_attribute(attr.to_s).serialize(value)
+            type = type_for_attribute(attr.to_s)
+            value = type.serialize(type.cast(value))
             "#{c.quote_table_name_for_assignment(table, attr)} = #{c.quote(value)}"
           end.join(", ")
         end
diff --git a/activerecord/test/cases/relation_test.rb b/activerecord/test/cases/relation_test.rb
index 8362722e12..a71d8de521 100644
--- a/activerecord/test/cases/relation_test.rb
+++ b/activerecord/test/cases/relation_test.rb
@@ -288,13 +288,18 @@ module ActiveRecord
         :string
       end
 
+      def cast(value)
+        raise value unless value == "value from user"
+        "cast value"
+      end
+
       def deserialize(value)
         raise value unless value == "type cast for database"
         "type cast from database"
       end
 
       def serialize(value)
-        raise value unless value == "value from user"
+        raise value unless value == "cast value"
         "type cast for database"
       end
     end