check_box selection

[MikeShank]

I'm using the check_box form helper and trying to do the following:
I have an array @collections I want to provide checkboxes for.
And I also have an @articles object that contains a "collections" method.
I want to have collections that an article belongs to selected.

I've been trying different variations of this to no avail:
from my controller

   def new
     @article = Article.new
     @collections = Collection.find(:all)
   end 

snipped from my form

 <% for collection in @collections %>
   <tr><td align="right"><%= check_box 'collection', 'id' %></td><td><%= collection.name %></td></tr>
 <% end %> 

[Fenrir2]

<% for @collection in @collections %>
   <tr><td align="right"><%= check_box 'collection', 'id' %></td><td><%= @collection.name %></td></tr>
<% end %>

Note the @collection.

[MikeShank]

Hi Fenrir2,
Thanks. That checks all of the items of @collections.
What I'm trying to do is only check or select only the items of @collections that happen to be in @article.collections
so If @collections contains ["a", "b", "c", "d"] and @article.collections contains ["a", "b"] I only want a and b checked

[Fenrir2]

Then this won't work ;-).

Maybe:

<% for collection in @collections %>
   <%= check_box_tag "collections", collection.id, @article.collections.include?(collection) %> <%= @collection.name %>
<% end %>

[MikeShank]

Fenrir2, that did work. Thanks.

But I'm confused as to why it works, what's the difference between check_box_tag and check_box?

[Luke Redpath]

check_box is designed to work with your active record model attributes where as check_box_tag is a plain jane tag generating helper.