Any ideas on why this is? The quantity field in mysql is INT, but I get back a string? This is preventing me from using the increment method.

>> @cart = Cart.new
=> #<Cart:0x2730f40 @new_record=true, @attributes={}>
>> @cart.items << Item.find(:first)
=> [#<Item:0x272d6ec @attributes={"vendor_id"=>"1", "updated_at"=>"2006-09-26 12:00:38", "catalog_id"=>"8050", "price"=>"185", "created_by"=>"Unit Tests", "unit"=>"ea", "updated_by"=>nil, "id"=>"1", "description"=>"CAP analog for SP6 MegaScript kit", "created_at"=>nil}>]
>> @cart.save
=> true
>> @cart.items.find(1).quantity
=> "1"
>> @cart.items.find(1).increment!(:quantity)
TypeError: can't convert Fixnum into String
        from /usr/local//lib/ruby/gems/1.8/gems/activerecord-1.14.4/lib/active_record/base.rb:1445:in `+'
        from /usr/local//lib/ruby/gems/1.8/gems/activerecord-1.14.4/lib/active_record/base.rb:1445:in `increment'
        from /usr/local//lib/ruby/gems/1.8/gems/activerecord-1.14.4/lib/active_record/base.rb:1451:in `increment!'
        from (irb):8

Using
-----
Rails 1.1.6
Mac OS 10.4.7
mysql Ver 14.7 Distrib 4.1.20, for apple-darwin8.5.1 (i686) using readline 4.3


mysql> desc carts_items;
+----------+---------+------+-----+---------+-------+
| Field    | Type    | Null | Key | Default | Extra |
+----------+---------+------+-----+---------+-------+
| cart_id  | int(11) |      |     | 0       |       |
| item_id  | int(11) |      |     | 0       |       |
| quantity | int(11) |      |     | 1       |       |
+----------+---------+------+-----+---------+-------+
3 rows in set (0.10 sec)


mysql> desc carts;
+-------+---------+------+-----+---------+----------------+
| Field | Type    | Null | Key | Default | Extra          |
+-------+---------+------+-----+---------+----------------+
| id    | int(11) |      | PRI | NULL    | auto_increment |
+-------+---------+------+-----+---------+----------------+
1 row in set (0.00 sec)

mysql> desc items;
+-------------+--------------+------+-----+---------+----------------+
| Field       | Type         | Null | Key | Default | Extra          |
+-------------+--------------+------+-----+---------+----------------+
| id          | int(11)      |      | PRI | NULL    | auto_increment |
| vendor_id   | int(11)      | YES  |     | NULL    |                |
| catalog_id  | varchar(255) | YES  |     | NULL    |                |
| description | varchar(255) | YES  |     | NULL    |                |
| unit        | varchar(255) | YES  |     | NULL    |                |
| price       | float        | YES  |     | NULL    |                |
| created_at  | datetime     | YES  |     | NULL    |                |
| updated_at  | datetime     | YES  |     | NULL    |                |
| created_by  | varchar(255) | YES  |     | NULL    |                |
| updated_by  | varchar(255) | YES  |     | NULL    |                |
+-------------+--------------+------+-----+---------+----------------+
10 rows in set (0.00 sec)

cart.rb
class Cart < ActiveRecord::Base
  has_and_belongs_to_many :items
end

item.rb
class Item < ActiveRecord::Base
  has_and_belongs_to_many :carts
end