Rails - Jul 2006 - model navigation problem with foreign key

Hi,
I have a table like this in schema.rb

  create_table "ac_rooms", :force => true do |t|
    t.column "roomname", :string, :limit => 50, :default =>
"", :null =>
false
    t.column "updated", :float, :default => 0.0, :null => false
    t.column "lines", :integer, :limit => 8, :default => 0,
:null =>
false
    t.column "created_at", :datetime
  end

and another in migration like this

  def self.up
    create_table :line_msgs do |t|
      t.column :sender_nick, :string
      t.column :content, :string
      t.column :room_id,  :integer, :null => false
      t.column :send_at, :timestamp
    end

    execute "alter table line_msgs
                      add constraint fk_line_msg_rooms
                      foreign key (room_id) references ac_rooms(id)"
  end

and i added the belongs_to :ac_room in line_msg.rb and has_many: 
:line_msgs to ac_room.rb in the model, but when i did

room = AcRoom.find(...)
<%= render(:partial => "line_msg", :collection =>
room.line_msgs) %>

but i get error

Mysql::Error: #42S22Unknown column ''line_msgs.ac_room_id'' in
''where
clause'': SELECT * FROM line_msgs WHERE (line_msgs.ac_room_id = 6)

my question is why rails make it into line_msgs.ac_room_id but not 
line_msgs.room_id, is there some stupid things i did, thanks.
Excuse me for my poor english




-- 
Posted via http://www.ruby-forum.com/.

Jia Liu wrote:
>   def self.up
>     create_table :line_msgs do |t|
>       t.column :sender_nick, :string
>       t.column :content, :string
>       t.column :room_id,  :integer, :null => false
>       t.column :send_at, :timestamp
>     end
> 
>     execute "alter table line_msgs
>                       add constraint fk_line_msg_rooms
>                       foreign key (room_id) references ac_rooms(id)"
>   end
> 
> and i added the belongs_to :ac_room in line_msg.rb and has_many: 
> :line_msgs to ac_room.rb in the model, but when i did
> 
> room = AcRoom.find(...)
> <%= render(:partial => "line_msg", :collection =>
room.line_msgs) %>
> 
> but i get error
> 
> Mysql::Error: #42S22Unknown column ''line_msgs.ac_room_id''
in ''where
> clause'': SELECT * FROM line_msgs WHERE (line_msgs.ac_room_id = 6)
> 
> my question is why rails make it into line_msgs.ac_room_id but not 
> line_msgs.room_id, is there some stupid things i did, thanks.
> Excuse me for my poor english
If you want Rails to use room_id as the foreign key, rather than
the default ac_room_id, you have to write the belongs_to as:

belongs_to :ac_room, :foreign_key => ''room_id''


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