Fix inspect with non-primary key id attribute

The `read_attribute` method always returns the primary key when asked to
read the `id` attribute, even if the primary key isn't named `id`, and
even if another attribute named `id` exists.

For the `inspect`, `attribute_for_inspect` and `pretty_print` methods,
this behaviour is undesirable, as they're used to examine the internal
state of the record. By using `_read_attribute` instead, we'll get the
real value of the `id` attribute.

1 files changed, 4 insertions, 0 deletions

diff --git a/activerecord/test/models/topic.rb b/activerecord/test/models/topic.rb
index 4aad6a4498..03430154db 100644
--- a/activerecord/test/models/topic.rb
+++ b/activerecord/test/models/topic.rb
@@ -138,6 +138,10 @@ class BlankTopic < Topic
   end
 end
 
+class TitlePrimaryKeyTopic < Topic
+  self.primary_key = :title
+end
+
 module Web
   class Topic < ActiveRecord::Base
     has_many :replies, dependent: :destroy, foreign_key: "parent_id", class_name: "Web::Reply"