title: undefined method on ActiveRecord::Relation object
body: <p>the following code</p>
  
  <pre><code>fieldvalue = Admin::FieldValue.where(:item_id =&gt; @admin_item.id, :field_id =&gt; key)
  fieldvalue.update_attributes(:value =&gt; value)
  </code></pre>
  
  <p>raise the following error</p>
  
  <pre><code>NoMethodError (undefined method `update_attributes' for #&lt;ActiveRecord::Relation:0x00000102dfc868&gt;):
  </code></pre>
  
  <p>why is it a <code>Relation</code> object and not a <code>FieldValue</code> object, what's the right way to manage this </p>