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# Defaults

Defaults are a handy way to avoid typing too much. Defaults are handled by sqlkit.db.defaults.Default class:

    from sqlkit.db  import defaults
    def_visita = defaults.Defaults('cliente_visita', metadata=db.metadata, local=False)
    def_visita.set_defaults( {'data' : def_visita.now, 'telefonata' : True})
    def_visita.set_default( title='Write a title...', duration=90)
    def_visita.fk('director_id', 'first_name', 'Olmi')

Defaults class requires a table name and a metaclass to know where to autoload/read table definition.

Defaults can be local to a sqlwidget or global to the application.

## set_default

The main method is `set_defaults` that requires a dictionary as argument with field_name as keys and field defaults as value. Alternatively `set_default` accepts keyword args.

## fk

Default in foreign key are set literally via `fk`. It will follow the reference and find the correct value

## now & today

attributes `now` and `today` will be substituted appropriately when creating the field

## SA defaults & server defaults

At the moment Sqlalchemy defaults are handled only in case of a fixed value (not a callable) nor defaults defined in the server. Adding a new record with an unhandled default will result in an empty value.

## Defaults local to the application

Sqlwidgets have an attribute called `defaults` that is an instance of `sqlwidget.db.defaults.Defaults` already correctly instantiated that allows to set defaults local only to the instance of sqlwidget they belong to.

You can use such a default in any of the following ways:

    m = SqlMask('movie', ...)
    m.defaults.set_default(actor=False)
    m.defaults.set_defaults( {'title' : 'write your preferred...'} )
    m.defaults.fk('director_id', 'first_name', 'Fellini')