Add messages_for

1 files changed, 7 insertions, 1 deletions

diff --git a/activemodel/lib/active_model/errors.rb b/activemodel/lib/active_model/errors.rb
index 805d042cac..bb64bc6264 100644
--- a/activemodel/lib/active_model/errors.rb
+++ b/activemodel/lib/active_model/errors.rb
@@ -65,6 +65,8 @@ module ActiveModel
 
     extend Forwardable
     def_delegators :@errors, :size, :clear, :blank?, :empty?
+    # TODO: forward all enumerable methods after `each` deprecation is removed.
+    def_delegators :@errors, :count
 
     LEGACY_ATTRIBUTES = [:messages, :details].freeze
 
@@ -199,7 +201,7 @@ module ActiveModel
     #   person.errors[:name]  # => ["cannot be nil"]
     #   person.errors['name'] # => ["cannot be nil"]
     def [](attribute)
-      where(attribute.to_sym).map { |error| error.message }
+      messages_for(attribute)
     end
 
     # Iterates through each error key, value pair in the error messages hash.
@@ -604,6 +606,10 @@ module ActiveModel
       def deprecation_removal_warning(method_name)
         ActiveSupport::Deprecation.warn("ActiveModel::Errors##{method_name} is deprecated and will be removed in Rails 6.1")
       end
+
+      def deprecation_rename_warning(old_method_name, new_method_name)
+        ActiveSupport::Deprecation.warn("ActiveModel::Errors##{old_method_name} is deprecated. Please call ##{new_method_name} instead.")
+      end
   end
 
   # Raised when a validation cannot be corrected by end users and are considered