From: Thufir <hawat.thufir@...>
Date: 2009-11-15T18:04:31+09:00
Subject: edit related record

There's a one-to-one relation between the base model "item" and the 
associated model "page," but the page table is empty and the structure 
seems wrong (no fk):

mysql>  
mysql> describe rss2mysql.pages;
+-------+---------+------+-----+---------+----------------+
| Field | Type    | Null | Key | Default | Extra          |
+-------+---------+------+-----+---------+----------------+
| id    | int(11) | NO   | PRI | NULL    | auto_increment | 
| html  | text    | YES  |     | NULL    |                | 
+-------+---------+------+-----+---------+----------------+
2 rows in set (0.00 sec)

mysql> Aborted
thufir@ARRAKIS:~/projects/rss2mysql$ 


It's necessary to use "through" so that the pages table will hold the fk 
for the id of the "item" to which a given page is associated with?

More importantly, *how* do you forge the link between a specific item and 
the page of which it has_one?  If it already has a page, probably I would 
want nothing done.  However, if it doesn't yet have a page, then I want 
to do something like:

page = Page.new
page = f.readlines.join
#somehow connect this page to the id of the current item
page.save

except that every example I see (of a rails controller) is using instance 
variables, and, presumably, using rails magic to establish the link 
between objects.


thufir@ARRAKIS:~/projects/rss2mysql$ 
thufir@ARRAKIS:~/projects/rss2mysql$ nl item.rb 
     1	require 'rubygems'
     2	require 'activerecord'
       
     3	class Item <  ActiveRecord::Base
     4	  has_one                 :page
     5	end
       
thufir@ARRAKIS:~/projects/rss2mysql$ nl page.rb 
     1	require 'rubygems'
     2	require 'activerecord'
       
     3	class Page <  ActiveRecord::Base
     4	  belongs_to              :item
     5	end
thufir@ARRAKIS:~/projects/rss2mysql$ 
thufir@ARRAKIS:~/projects/rss2mysql$ nl scrape.rb 
     1	require 'rubygems'
     2	require 'activerecord'
     3	require 'yaml'
     4	require 'item'
     5	require 'open-uri'
     6	require 'pp'
       
       
     7	db = YAML::load(File.open('database.yml'))
       
     8	ActiveRecord::Base.establish_connection(
     9	:adapter  => db["development"]["adapter"],
    10	:host   => db["development"]["host"],
    11	:username => db["development"]["username"],
    12	:password => db["development"]["password"],
    13	:database => db["development"]["database"])
       
       
    14	items = Item.find(:all)
       
    15	items.each do |item|
    16	  open(item.url,
    17	  "User-Agent" => "Mozilla/5.0 (X11; U; Linux i686; en-US; 
rv:1.9.0.15) Gecko/2009102815 Ubuntu/9.04 (jaunty) Firefox/3.0.15"){|f|
       
    18	    #@item.page = @page   ?why use instance vars?
       
       
    19	    item.page.html = f.readlines.join
    20	    item.save}
    21	end
thufir@ARRAKIS:~/projects/rss2mysql$ 




thanks,  

Thufir