  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  
  .. method:: pre_save(self, model_instance, add)
  
  This method is called just prior to :meth:`get_db_prep_save` and should return
  the value of the appropriate attribute from ``model_instance`` for this field.
  The attribute name is in ``self.attname`` (this is set up by
  :class:`~django.db.models.Field`). If the model is being saved to the database
  for the first time, the ``add`` parameter will be ``True``, otherwise it will be
  ``False``.
 
</s> remove .. method:: pre_save(self, model_instance, add)
 </s> add .. method:: Field.pre_save(self, model_instance, add) </s> remove parameters (which is implemented by ``get_db_prep_value``).
 </s> add parameters (which is implemented by :meth:`.get_db_prep_value`). </s> remove This is the reverse of :meth:`to_python` when working with the
 </s> add This is the reverse of :meth:`.to_python` when working with the </s> remove The :meth:`db_type` method is only called by Django when the framework
constructs the ``CREATE TABLE`` statements for your application -- that is, when
you first create your tables. It's not called at any other time, so it can
afford to execute slightly complex code, such as the ``connection.settings_dict``
check in the above example.
 </s> add The :meth:`.db_type` method is only called by Django when the framework
constructs the ``CREATE TABLE`` statements for your application -- that is,
when you first create your tables. It's not called at any other time, so it can
afford to execute slightly complex code, such as the
``connection.settings_dict`` check in the above example. </s> remove ``get_db_prep_value``, you shouldn't need to implement this method
 </s> add :meth:`.get_db_prep_value`, you shouldn't need to implement this method
This method is called just prior to :meth:`.get_db_prep_save` and should return
  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  
  .. method:: pre_save(self, model_instance, add)
  
This method is called just prior to :meth:`.get_db_prep_save` and should return
  the value of the appropriate attribute from ``model_instance`` for this field.
  The attribute name is in ``self.attname`` (this is set up by
  :class:`~django.db.models.Field`). If the model is being saved to the database
  for the first time, the ``add`` parameter will be ``True``, otherwise it will be
  ``False``.
keep keep keep keep replace keep keep keep keep keep
 Fixed #15308 -- Sphinx/reST fixes for the Custom Model Fields docs.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@15547 bcc190cf-cafb-0310-a4f2-bffc1f526a37 
docs/howto/custom-model-fields.txt