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PORails - How to associate models in one direction only
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  1. PORails - How to associate models in one direction only
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    copied!<p>Ahoy guys,</p> <p>I'm new to Rails, and I feel like I'm definitely missing something crucial here, because it seems like this should be an easily solvable problem.</p> <p>I've set up a <code>Page</code> model and a <code>Coord</code> model (with help from the getting started tutorial), and <code>Coord</code> successfully <code>belongs_to</code> <code>Page</code>. I'm trying to apply similar logic to make another model, <code>Comment</code>, belong to <code>Coord</code>, and only belong to <code>Page</code> via <code>Coord</code>.</p> <p>Do I use <code>:through</code> for an association that (I think) only needs to link in one direction? As in Page &lt; Coord &lt; Comment? At the moment I have:</p> <pre><code>class Page &lt; ActiveRecord::Base attr_accessible :description, :name has_many :coords has_many :comments, :through =&gt; :coords end </code></pre> <p>Coord model:</p> <pre><code>class Coord &lt; ActiveRecord::Base belongs_to :page has_many :comments attr_accessible :coordinates, :x, :y validates :x, :presence =&gt; true validates :y, :presence =&gt; true end </code></pre> <p>Then the Comment model:</p> <pre><code>class Comment &lt; ActiveRecord::Base belongs_to :coord belongs_to :page attr_accessible :body end </code></pre> <p>I still keep getting errors about <code>comments</code> being an undefined method, or an association not being defined. Apologies if this is a common question, I don't personally know anyone who knows Rails, and the documentation only has examples too far removed from mine (to my knowledge). Thanks</p> <p><strong>Edit: added DB schema</strong></p> <pre><code>ActiveRecord::Schema.define(:version =&gt; 20120712170243) do create_table "comments", :force =&gt; true do |t| t.text "body" t.integer "coord_id" t.integer "page_id" t.datetime "created_at", :null =&gt; false t.datetime "updated_at", :null =&gt; false end add_index "comments", ["coord_id"], :name =&gt; "index_comments_on_coord_id" add_index "comments", ["page_id"], :name =&gt; "index_comments_on_page_id" create_table "coords", :force =&gt; true do |t| t.string "coordinates" t.integer "x" t.integer "y" t.integer "page_id" t.datetime "created_at", :null =&gt; false t.datetime "updated_at", :null =&gt; false end add_index "coords", ["page_id"], :name =&gt; "index_coords_on_page_id" create_table "pages", :force =&gt; true do |t| t.string "name" t.string "description" t.datetime "created_at", :null =&gt; false t.datetime "updated_at", :null =&gt; false end end </code></pre>
 

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