title: Setting the value of a form field from a Query
body: <p>I have a form field where one of the values has a default value defined in a an application settings table. The user would see the default value upon display of the create form, but could change it to another value if they wanted prior to saving the new row.</p>
  
  <p>I don't see any way in the field defaults to specify that the default value is the result of an SQL query (e.g. select default_rate from app_defaults where row_key = 1).</p>
  
  <p>Surely this has to be possible, but how?</p>