SET_NULL [source] Set the ForeignKey null; this is only possible if null

ForeignKey.swappable Controls the migration framework’s reaction if this ForeignKey is pointing at a swappable

delete() Performs an SQL delete query on all rows in the QuerySet and returns the number of objects deleted and

Field.is_relation Boolean flag that indicates if a field contains references to one or more other models for its functionality

Field.help_text Extra “help” text to be displayed with the form widget. It’s useful for documentation even if your field isn’t

prefetch_related(*lookups) Returns a QuerySet that will automatically retrieve, in a single batch, related objects

ForeignKey.related_name The name to use for the relation from the related object back to this one. It’s also the default value

count() Returns an integer representing the number of objects in the database matching the QuerySet. The count()

ForeignKey.on_delete When an object referenced by a ForeignKey is deleted, Django will emulate the behavior of

class Aggregate(expression, output_field=None, **extra) [source]