title: Active Record Model Default Mapping
body: <p>I am fairly new to Rails, and one thing I don't understand is where in the rails official documentation it says that the database defaults map to the models.</p>
  <p>For example, if I put a default value on a column in a migration, I would expect that the default value is inserted for a particular record when it is saved to the database. However I have noticed that when I do <code>Record.new</code> the model attributes already have those defaults that were set in the database! This is useful because it means I don't have to explicitly set it when instantiating a new model object, but where in the docs does it say this automatic setting of default on new objects happens?</p>