1 files changed, 19 insertions, 7 deletions
diff --git a/activemodel/lib/active_model/errors.rb b/activemodel/lib/active_model/errors.rb
index 8326853879..e35ed03e74 100644
--- a/activemodel/lib/active_model/errors.rb
+++ b/activemodel/lib/active_model/errors.rb
@@ -3,6 +3,7 @@
 require 'active_support/core_ext/array/conversions'
 require 'active_support/core_ext/string/inflections'
 require 'active_support/core_ext/object/deep_dup'
+require 'active_support/core_ext/string/filters'
 
 module ActiveModel
   # == Active \Model \Errors
@@ -33,11 +34,11 @@ module ActiveModel
   #       send(attr)
   #     end
   #
-  #     def Person.human_attribute_name(attr, options = {})
+  #     def self.human_attribute_name(attr, options = {})
   #       attr
   #     end
   #
-  #     def Person.lookup_ancestors
+  #     def self.lookup_ancestors
   #       [self]
   #     end
   #   end
@@ -123,9 +124,9 @@ module ActiveModel
 
     # Set messages for +key+ to +value+.
     #
-    #   person.errors.get(:name) # => ["cannot be nil"]
+    #   person.errors[:name] # => ["cannot be nil"]
     #   person.errors.set(:name, ["can't be nil"])
-    #   person.errors.get(:name) # => ["can't be nil"]
+    #   person.errors[:name] # => ["can't be nil"]
     def set(key, value)
       ActiveSupport::Deprecation.warn(<<-MESSAGE.squish)
         ActiveModel::Errors#set is deprecated and will be removed in Rails 5.1.
@@ -138,12 +139,12 @@ module ActiveModel
 
     # Delete messages for +key+. Returns the deleted messages.
     #
-    #   person.errors.get(:name)    # => ["cannot be nil"]
+    #   person.errors[:name]    # => ["cannot be nil"]
     #   person.errors.delete(:name) # => ["cannot be nil"]
-    #   person.errors.get(:name)    # => []
+    #   person.errors[:name]    # => []
     def delete(key)
-      messages.delete(key)
       details.delete(key)
+      messages.delete(key)
     end
 
     # When passed a symbol or a name of a method, returns an array of errors
@@ -524,4 +525,15 @@ module ActiveModel
   #   # => ActiveModel::StrictValidationFailed: Name can't be blank
   class StrictValidationFailed < StandardError
   end
+
+  # Raised when unknown attributes are supplied via mass assignment.
+  class UnknownAttributeError < NoMethodError
+    attr_reader :record, :attribute
+
+    def initialize(record, attribute)
+      @record = record
+      @attribute = attribute
+      super("unknown attribute '#{attribute}' for #{@record.class}.")
+    end
+  end
 end