If you have the following model:

class Location(models.Model)
	continent = models.ForeignKey(Continent)
	country = models.ForeignKey(Country)
	area = models.ForeignKey(Area)
	city = models.CharField(max_length=50)
	street = models.CharField(max_length=100)

And you want that if you select a continent only the countries are available that are located on this continent and the same for areas you can do the following:

from smart_selects.db_fields import ChainedForeignKey 

class Location(models.Model)
	continent = models.ForeignKey(Continent)
	country = ChainedForeignKey(
		Country, 
		chained_field="continent",
		chained_model_field="continent", 
		show_all=False, 
		auto_choose=True
	)
	area = ChainedForeignKey(Area, chained_field="country", chained_model_field="country")
	city = models.CharField(max_length=50)
	street = models.CharField(max_length=100)

This example asumes that the Country Model has a "continent" field and that the Area model has "country" field.

• The chained field is the field on the same model the field should be chained too.
• The chained model field is the field of the chained model that corresponds to the model linked too by the chained field.
• show_all indicates if only the filtered results should be shown or if you also want to display the other results further down.
• auto_choose indicates that if there is only one option if it should be autoselected.

If you have the following model:

class Location(models.Model)
	continent = models.ForeignKey(Continent)
	country = models.ForeignKey(Country)

And you want that all countries are grouped by the Continent and that Groups are used in the select change to the following:

from smart_selects.db_fields import GroupedForeignKey

class Location(models.Model)
	continent = models.ForeignKey(Continent)
	country = models.GroupedForeignKey(Country, "continent")

This example assumes that the Country Model has a foreignKey to Continent named "continent" finished.

1. Add "smart_selects" to your INSTALLED_APPS
2. Bind the smart_selects urls.py into your main urls.py with something like: url(r'^chaining/', include('smart_selects.urls')), This is needed for the chained-selects.
3. Profit

USE_DJANGO_JQUERY : By default, smart_selects will use the bundled jQuery from Django 1.2's admin area. Set USE_DJANGO_JQUERY = False to disable this behaviour.

JQUERY_URL : By default, jQuery will be loaded from Google's CDN. If you would prefer to use a different version put the full URL here.