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POAttribute in Rails model appears to be nil when it's not
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  1. POAttribute in Rails model appears to be nil when it's not
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    copied!<p>I have a very annoying and hard to figure out bug in my rails project.</p> <p>After having created a bunch of models and their relations, I want to list them.</p> <p>But I keep getting an Error "can't dup NilClass". That is, until I restart the server. Then I can list them just fine.</p> <p>Debugging this issue, it turns out that the Error gets raised in a method in one of the models when I try to return the value of one of its attributes. I have a breakpoint in the method, and this is what I get in the debugger:</p> <pre> (rdb:5) self #&lt;Bar id: 1037, foo: 2237, created_at: "2009-06-09 19:52:11", updated_at: "2009-06-09 19:52:47"&gt; (rdb:5) foo TypeError Exception: can't dup NilClass (rdb:5) attributes[:foo] nil (rdb:5) attributes["foo"] 2237 </pre> <p>I doesn't matter if I reload the page. I get the same error until I restart the server.</p> <p>My model basically looks like this (the error occurs in method baz):</p> <pre><code>class FooBar &lt; ActiveRecord::Base belongs_to :foo, :class_name =&gt; "BarFoo", :foreign_key =&gt; "foo", :dependent =&gt; :destroy belongs_to :bar, :class_name =&gt; "BarFoo", :foreign_key =&gt; "bar", :dependent =&gt; :destroy validates_presence_of :foo, :on =&gt; :create def baz [foo, bar].compact end end </code></pre> <p>My schema looks like this:</p> <pre><code>create_table "foo_bar", :force =&gt; true do |t| t.integer "foo" t.integer "bar" t.datetime "created_at" t.datetime "updated_at" end </code></pre> <p><strong>Update:</strong></p> <p>Before I get any more answers pointing out that :foo and "foo" are not the same: I'm aware that they are not equal, but that is not the issue here. </p> <p>And, I just confirmed that read_attribute("foo") does return the same as read_attribute(:foo). And so does self[:foo] and self["foo"]. None of these return nil. They do however all return the id of foo, instead of foo itself.</p>
 

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