1 files changed, 8 insertions, 13 deletions
diff --git a/activemodel/lib/active_model/deprecated_error_methods.rb b/activemodel/lib/active_model/deprecated_error_methods.rb
index e0cbd9ba29..433de8931a 100644
--- a/activemodel/lib/active_model/deprecated_error_methods.rb
+++ b/activemodel/lib/active_model/deprecated_error_methods.rb
@@ -1,18 +1,18 @@
 module ActiveModel
   module DeprecatedErrorMethods
     def on(attribute)
-      ActiveSupport::Deprecation.warn "Errors#on have been deprecated, use Errors#[] instead"
-      self[attribute]
+      message = "Errors#on have been deprecated, use Errors#[] instead.\n"
+      message << "Also note that the behaviour of Errors#[] has changed. Errors#[] now always returns an Array. An empty Array is "
+      message << "returned when there are no errors on the specified attribute."
+      ActiveSupport::Deprecation.warn(message)
+
+      errors = self[attribute]
+      errors.size < 2 ? errors.first : errors
     end
 
     def on_base
       ActiveSupport::Deprecation.warn "Errors#on_base have been deprecated, use Errors#[:base] instead"
-      on(:base)
-    end
-
-    def add(attribute, msg = Errors.default_error_messages[:invalid])
-      ActiveSupport::Deprecation.warn "Errors#add(attribute, msg) has been deprecated, use Errors#[attribute] << msg instead"
-      self[attribute] << msg
+      ActiveSupport::Deprecation.silence { on(:base) }
     end
 
     def add_to_base(msg)
@@ -25,11 +25,6 @@ module ActiveModel
       self[attribute].any?
     end
 
-    def full_messages
-      ActiveSupport::Deprecation.warn "Errors#full_messages has been deprecated, use Errors#to_a instead"
-      to_a
-    end
-
     def each_full
       ActiveSupport::Deprecation.warn "Errors#each_full has been deprecated, use Errors#to_a.each instead"
       to_a.each { |error| yield error }