Hi everyone, I've tried posting the same question to the list last Friday but somehow did not see it being posted.. I've just started with Rails and Ruby. I just started to play one of those RPG and to get my feet wet I'm writing an app to keep track of item fusions. So the scoop is that item can be fused with another items to create a higher level item. The higher level items can be fused to create even higher level items ... etc. I'm using MySQL to store the data. Here is how I have setup the database: CREATE TABLE `items` ( `id` INTEGER(11) NOT NULL AUTO_INCREMENT, `name` VARCHAR(255) , `cat_id` INTEGER(11), `rank` INTEGER , PRIMARY KEY(`id`) ); CREATE TABLE `cats` ( `id` INTEGER(11) NOT NULL AUTO_INCREMENT, `name` VARCHAR(255), PRIMARY KEY(`id`) ); CREATE TABLE `fusions` ( `id` INTEGER(11) NOT NULL AUTO_INCREMENT, `item1_id` INTEGER(11), `item2_id` INTEGER(11) , `product_id` INTEGER(11), PRIMARY KEY(`id`) ); Now... Creating one-to-many relationship for item/category is cake. How do I set up my model for item and fusion so I can have something like below in my view? <% for fusion in @item.fusions %> <%= fusion.item1.name %> + <%= fusion.item2.name %> <% end %> BTW I've tried CREATE TABLE `fusions` ( `item1_id` INTEGER(11), `item2_id` INTEGER(11) , `product_id` INTEGER(11), PRIMARY KEY(`item1_id`,`item2_id`) ); to have has_and_belongs_to_many relationship but it did not work. I think it has to do with join table having only the id's for the items that are joined. I've also tried to use info from http://wiki.rubyonrails.org/rails/pages/HowToUseMa... but was unsuccessful. Because I was unable to come up with a good model for item/fusion and to limit my database usage, I'm resorting to having controller send fusions and items ordered by id and doing the following in my view. <% for fusion in @fusions %> <% item1 = @Items[fusion.item1_id.to_i - 1] <% item2 = @Items[fusion.item2_id.to_i - 1] <%= item1.name %> + <%= item2.name %> <% end %> Any ideas? Marcin
on 2005-12-19 17:32
on 2005-12-19 18:42
forgive me if i don't understand correctly, but i think habtm is the answer, using self-referential joins. http://wiki.rubyonrails.com/rails/pages/HowToCreat... down to 2nd half of page "A Slight Alternative")
on 2005-12-22 01:09
Thanks Chirs, Unless I'm doing something wrong I getting the following error Showing app/views/item/show.rhtml where line #32 raised: undefined method `product' for #<Item:0x39460c8> Extracted source (around line #32): 29: <% for f in @item.fusions %> 30: <tr> 31: <td> <%= h f.id -%> </td> 32: <td> <%= h f.product_id -%> <%= h f.product.name -%> </td> 33: <td> <%= h f.item1_id -%> </td> 34: <td> <%= h f.item2_id -%> </td> 35: </tr> My item.rb: class Item < ActiveRecord::Base has_and_belongs_to_many :fusions, :class_name => 'Item', :join_table => 'fusions', :foreign_key => 'product_id', :association_foreign_key => 'id' end How do I associate item1_id, item2_id and product_id in the fusions table to Item? I don't get the error when I update line 32 of show.rhtml to: 32: <td> <%= h f.product_id -%> </td> I've also experimented with creating habtm table with Item_id and fusion_id and fusions table that only has id, item1_id and item2_id. I found that using http://wiki.rubyonrails.com/rails/pages/HowToCreat... I'm displaying only portions of fusions (only once where fusion_id is less than max item_id) Any ideas?