mirror of
https://github.com/django/django.git
synced 2024-11-25 07:59:34 +01:00
797957fb48
CAST() must be wrapped in parentheses to be recognized as an expression on SQLite.
Regression in 7414704e88.
71 lines
2.2 KiB
Python
71 lines
2.2 KiB
Python
"""
|
|
Callable defaults
|
|
|
|
You can pass callable objects as the ``default`` parameter to a field. When
|
|
the object is created without an explicit value passed in, Django will call
|
|
the method to determine the default value.
|
|
|
|
This example uses ``datetime.datetime.now`` as the default for the ``pub_date``
|
|
field.
|
|
"""
|
|
|
|
from datetime import datetime
|
|
from decimal import Decimal
|
|
|
|
from django.db import models
|
|
from django.db.models.functions import Coalesce, ExtractYear, Now, Pi
|
|
from django.db.models.lookups import GreaterThan
|
|
|
|
|
|
class Article(models.Model):
|
|
headline = models.CharField(max_length=100, default="Default headline")
|
|
pub_date = models.DateTimeField(default=datetime.now)
|
|
|
|
def __str__(self):
|
|
return self.headline
|
|
|
|
|
|
class DBArticle(models.Model):
|
|
"""
|
|
Values or expressions can be passed as the db_default parameter to a field.
|
|
When the object is created without an explicit value passed in, the
|
|
database will insert the default value automatically.
|
|
"""
|
|
|
|
headline = models.CharField(max_length=100, db_default="Default headline")
|
|
pub_date = models.DateTimeField(db_default=Now())
|
|
cost = models.DecimalField(
|
|
max_digits=3, decimal_places=2, db_default=Decimal("3.33")
|
|
)
|
|
|
|
class Meta:
|
|
required_db_features = {"supports_expression_defaults"}
|
|
|
|
|
|
class DBDefaults(models.Model):
|
|
both = models.IntegerField(default=1, db_default=2)
|
|
null = models.FloatField(null=True, db_default=1.1)
|
|
|
|
|
|
class DBDefaultsFunction(models.Model):
|
|
number = models.FloatField(db_default=Pi())
|
|
year = models.IntegerField(db_default=ExtractYear(Now()))
|
|
added = models.FloatField(db_default=Pi() + 4.5)
|
|
multiple_subfunctions = models.FloatField(db_default=Coalesce(4.5, Pi()))
|
|
case_when = models.IntegerField(
|
|
db_default=models.Case(models.When(GreaterThan(2, 1), then=3), default=4)
|
|
)
|
|
|
|
class Meta:
|
|
required_db_features = {"supports_expression_defaults"}
|
|
|
|
|
|
class DBDefaultsPK(models.Model):
|
|
language_code = models.CharField(primary_key=True, max_length=2, db_default="en")
|
|
|
|
|
|
class DBDefaultsFK(models.Model):
|
|
language_code = models.ForeignKey(
|
|
DBDefaultsPK, db_default="fr", on_delete=models.CASCADE
|
|
)
|