If you have the following model:

class Continent(models.Model):
    	name = models.CharField(max_length=255)

class Country(models.Model):
    	continent = models.ForeignKey(Continent)
    	name = models.CharField(max_length=255)

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)

The chained_field indicates the field on the same model that should be chained to. In the Continent, Country, Location example, chained_field is the name of the field continent in model Location.

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

The chained_model_field indicates the field of the chained model that corresponds to the model linked to by the chained_field. In the Continent, Country, Location example, chained_model_field is the name of field continent in Model Country.

class Country(models.Model):
    	continent = models.ForeignKey(Continent)

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 if auto select the choice when there is only one available choice.

Similar to Chained Selects, but behaves like ManyToManyField. For example:

class Publication(models.Model):
	name = models.CharField(max_length=255)

class Writer(models.Model):
    	name = models.CharField(max_length=255)
    	publications = models.ManyToManyField('Publication', blank=True, null=True)

class Book(models.Model):
    	publication = models.ForeignKey(Publication)
    	writer = ChainedManyToManyField(
        	Writer,
        	chained_field="publication",
        	chained_model_field="publications",
        	)
    	name = models.CharField(max_length=255)

The chained_field indicates the field on the same model that should be chained to. In the Publication, Writer, Book example, chained_field is the name of the field publication in model Book.

class Book(models.Model):
    	publication = models.ForeignKey(Publication)

The chained_model_field indicates the field of the chained model that corresponds to the model linked to by the chained_field. In the Publication, Writer, Book example, chained_model_field is the name of field publications in Model Writer.

class Writer(models.Model):
    	publications = models.ManyToManyField('Publication', blank=True, null=True)

auto_choose indicates if auto select the choice when there is only one available choice.

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 = 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 into your project's urls.py. This is needed for the Chained Selects and Chained ManyToMany Selects. For example:

urlpatterns = patterns('',
    url(r'^admin/', include(admin.site.urls)),
    url(r'^chaining/', include('smart_selects.urls')),
)

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.