Forum: Ruby on Rails Listing of Category error

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haneef5k (Guest)
on 2009-04-24 18:52
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Im trying to see posts index page, In tat im showing category list, im
using collect method it show error..

ActiveRecord::StatementInvalid in Posts#index
Showing app/views/posts/index.html.erb where line #19 raised:

Mysql::Error: Unknown column 'categories_posts.category_id' in 'on
clause': SELECT `categories`.* FROM `categories`  INNER JOIN
`categories_posts` ON `categories`.id =
`categories_posts`.category_id    WHERE ((`categories_posts`.post_id =

Extracted source (around line #19):

16:     <td><%= post.created_at.strftime('%m/%d/%y %I:%m %p') %></td>
17:     <td><%= h(post.title) %></td>
18:     <td><%= h( if %></td>
19:     <td><%= post.categories.collect {|cat| [] }.join(",")
20:     <td><%= h(post.status) %></td>
21:     <td><%= post.comments_count %>

pls help me,, im new to RoR..??
Franco C. (Guest)
on 2009-04-24 20:13
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You must declare a has_many :categories in the Post model and a
belongs_to :post in the Category model (if the category table has a
post_id column, if not keep reading). If you don't do that, you need
to create a categories_posts table with two columns: category_id and a


Franco C..
haneef5k (Guest)
on 2009-04-24 22:21
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Im new to Ror,  i want to do some userful website can u tell me ur
advice and wat steps i should to take basically in Ruby on Rails..??
then im trying to understand tat ( models, controller, action ) it
pls help me..

Franco C. (Guest)
on 2009-04-24 22:35
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You can read the Agile Web D. With Rails (http://, is a very good book. It explains step
by step the framework and a very common (but usefull) workflow.


Franco C..
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