Move writing unknown column exception to null attribute

Making this change revealed several subtle bugs related to models with
no primary key, and anonymous classes. These have been fixed as well,
with regression tests added.

5 files changed, 9 insertions, 11 deletions

diff --git a/activerecord/lib/active_record/attribute.rb b/activerecord/lib/active_record/attribute.rb
index 33c20bb5cc..6d38224830 100644
--- a/activerecord/lib/active_record/attribute.rb
+++ b/activerecord/lib/active_record/attribute.rb
@@ -90,6 +90,11 @@ module ActiveRecord
       def value
         nil
       end
+
+      def with_value_from_database(value)
+        raise ActiveModel::MissingAttributeError, "can't write unknown attribute `#{name}`"
+      end
+      alias_method :with_value_from_user, :with_value_from_database
     end
 
     class Uninitialized < Attribute # :nodoc:
diff --git a/activerecord/lib/active_record/attribute_methods/primary_key.rb b/activerecord/lib/active_record/attribute_methods/primary_key.rb
index 1c81a5b71b..cadad60ddd 100644
--- a/activerecord/lib/active_record/attribute_methods/primary_key.rb
+++ b/activerecord/lib/active_record/attribute_methods/primary_key.rb
@@ -83,12 +83,9 @@ module ActiveRecord
         end
 
         def get_primary_key(base_name) #:nodoc:
-          return 'id' if base_name.blank?
-
-          case primary_key_prefix_type
-          when :table_name
+          if base_name && primary_key_prefix_type == :table_name
             base_name.foreign_key(false)
-          when :table_name_with_underscore
+          elsif base_name && primary_key_prefix_type == :table_name_with_underscore
             base_name.foreign_key
           else
             if ActiveRecord::Base != self && table_exists?
diff --git a/activerecord/lib/active_record/attribute_methods/write.rb b/activerecord/lib/active_record/attribute_methods/write.rb
index 94fce2db60..b3c8209a74 100644
--- a/activerecord/lib/active_record/attribute_methods/write.rb
+++ b/activerecord/lib/active_record/attribute_methods/write.rb
@@ -70,10 +70,6 @@ module ActiveRecord
         attr_name = attr_name.to_s
         attr_name = self.class.primary_key if attr_name == 'id' && self.class.primary_key
 
-        unless has_attribute?(attr_name) || self.class.columns_hash.key?(attr_name)
-          raise ActiveModel::MissingAttributeError, "can't write unknown attribute `#{attr_name}'"
-        end
-
         if should_type_cast
           @attributes.write_from_user(attr_name, value)
         else
diff --git a/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb b/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb
index 3ef8878ad1..def04dbed2 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb
@@ -381,7 +381,7 @@ module ActiveRecord
       end
 
       def table_exists?(name)
-        return false unless name
+        return false unless name.present?
         return true if tables(nil, nil, name).any?
 
         name          = name.to_s
diff --git a/activerecord/lib/active_record/core.rb b/activerecord/lib/active_record/core.rb
index c434b0d40a..3321e268d5 100644
--- a/activerecord/lib/active_record/core.rb
+++ b/activerecord/lib/active_record/core.rb
@@ -521,7 +521,7 @@ module ActiveRecord
 
     def init_internals
       pk = self.class.primary_key
-      unless @attributes.include?(pk)
+      if pk && !@attributes.include?(pk)
         @attributes.write_from_database(pk, nil)
       end