rails HABTM joins and inconveniences

Question

I have a working HABTM association between the models

Posts and Users... the posts_users table is as advertised and both have the necessary has_and_belongs_to_many in their model.rb

And if I use User.find(1).posts it will find all the posts with the valid username

My question is how to deal with this situation.

I want to use

user.posts.find(1234) or really from the controller the eq:

current_user.posts.find(params[:id])

To protect myself from other users jumping around. However this usage has some strange results. It does work, but instead of the id being a valid id for a particular post or all the posts, it returns the id of 1 instead of say, the real one of 1234. So further joins such as:

user.posts.find(1234).comments

don't work or are invalid.

I tried throwing in all a few places for good measure, as that has sometimes worked for other awkward situations in the past. With a few stranger encounters still.

user.posts.all.first works and returns the correct ID!, but using first isn't really helpful. user.posts.all.find(6933) returns #<Enumerable::Enumerator:0x105343630>

Also tried various combination with (:post_id => 1234) returning an id of always 1.

Any ideas?

I think the issue is that because it's an association, you will always see an array/enumerable returned. — Toby Hede, Feb 23 '10 at 04:15
Also: if you know the post_id, why do you need to map through the user at all? — Toby Hede, Feb 23 '10 at 04:16

score 1 · Accepted Answer · answered Feb 23 '10 at 08:05

1

This is most likely because your join table posts_users has an id column. In your migration your join table should look like this:

create_table :posts_users, :id => false do |t|
  t.references :posts
  t.references :users
end

answered Feb 23 '10 at 08:05

Ben Marini

2,633
1
21
13

That works perfectly thanks! Except if I attempt to use find() with a friendly_id instead of an ID, friendly_id returns the correct record but with the friendly_id's ID and not the posts. – holden Feb 23 '10 at 12:11
Not sure what your exact problem is there, but I have gotten around some of these issues before with an explicit `:select => 'tablename.*'` in the find method to ensure only one table's columns were pulled back. – Ben Marini Feb 23 '10 at 17:03

score 0 · Answer 2 · answered Feb 23 '10 at 05:33

0

How about user has many comments through posts. Then something like user.comments.find(:all, :conditions => { :post_id => 1234 }

answered Feb 23 '10 at 05:33

Gordon Isnor

2,065
1
19
32

rails HABTM joins and inconveniences

2 Answers2