1 files changed, 50 insertions, 0 deletions
diff --git a/activerecord/lib/active_record/coders/yaml_column.rb b/activerecord/lib/active_record/coders/yaml_column.rb
new file mode 100644
index 0000000000..11559141c7
--- /dev/null
+++ b/activerecord/lib/active_record/coders/yaml_column.rb
@@ -0,0 +1,50 @@
+# frozen_string_literal: true
+
+require "yaml"
+
+module ActiveRecord
+  module Coders # :nodoc:
+    class YAMLColumn # :nodoc:
+      attr_accessor :object_class
+
+      def initialize(attr_name, object_class = Object)
+        @attr_name = attr_name
+        @object_class = object_class
+        check_arity_of_constructor
+      end
+
+      def dump(obj)
+        return if obj.nil?
+
+        assert_valid_value(obj, action: "dump")
+        YAML.dump obj
+      end
+
+      def load(yaml)
+        return object_class.new if object_class != Object && yaml.nil?
+        return yaml unless yaml.is_a?(String) && /^---/.match?(yaml)
+        obj = YAML.load(yaml)
+
+        assert_valid_value(obj, action: "load")
+        obj ||= object_class.new if object_class != Object
+
+        obj
+      end
+
+      def assert_valid_value(obj, action:)
+        unless obj.nil? || obj.is_a?(object_class)
+          raise SerializationTypeMismatch,
+            "can't #{action} `#{@attr_name}`: was supposed to be a #{object_class}, but was a #{obj.class}. -- #{obj.inspect}"
+        end
+      end
+
+      private
+
+        def check_arity_of_constructor
+          load(nil)
+        rescue ArgumentError
+          raise ArgumentError, "Cannot serialize #{object_class}. Classes passed to `serialize` must have a 0 argument constructor."
+        end
+    end
+  end
+end