Sinatra activerecord initialize - ruby

Question

I got a strange situation.Could somebody give me advise ?
I am developing an App with
Ruby1.8.7
Sinatra 1.4.4
Activerecord 3.2.14
Mysql 5.6.19
I almost finish developing but at the last moment I got stack.
I have two tables in MySQL.
CREATE TABLE items(
id INT PRIMARY KEY AUTO_INCREMENT NOT NULL,
type text,
keyword text,
postid INT,
created_at datetime NOT NULL);
CREATE TABLE comments(
id INT PRIMARY KEY AUTO_INCREMENT NOT NULL,
comment text,
yourname INT,
postid INT,
created_at datetime NOT
NULL);
In Sinatra app , I declared class.
class Comment < ActiveRecord::Base end
class Item < ActiveRecord::Base end
For debugging purpose , I wrote this code and run.
get "/l" do
# New comment and set initial value.
y={:yourname =>"3",:comment =>"commenttest"}
com = Comment.new(y)
p com.attribute_names()
p com
# New items and set initial value.
kensaku = {:type=>"000"}
k = Item.new(kensaku)
p k.attribute_names()
p k
k.type="555"
p k
end
So now I found very interesting things on console.
Comment class succeeded to new with initial value.
But Item class succeeded to new but it is not set initial value.
I wonder why it happens ?
#-- Comment class
["postid", "id", "comment", "created_at", "yourname"]
#<Comment id: nil, comment: "commenttest", yourname: 3, postid: nil, created_at: nil>
#-- Item class
["type", "postid", "id", "keyword", "created_at"]
#<Item id: nil, type: nil, keyword: nil, postid: nil, created_at: nil>
#<Item id: nil, type: "555", keyword: nil, postid: nil, created_at: nil>

Answer 1

The column name type is a reserved word in ActiveRecord:
While these column names are optional, they are in fact reserved by
Active Record. Steer clear of reserved keywords unless you want the
extra functionality. For example, type is a reserved keyword used to
designate a table using Single Table Inheritance (STI). If you are not
using STI, try an analogous keyword like "context", that may still
accurately describe the data you are modeling.