Fixed #470 -- Added support for database defaults on fields.

Special thanks to Hannes Ljungberg for finding multiple implementation
gaps.

Thanks also to Simon Charette, Adam Johnson, and Mariusz Felisiak for
reviews.

1 files changed, 44 insertions, 0 deletions

diff --git a/tests/field_defaults/models.py b/tests/field_defaults/models.py
index b95005192a..5f9c38a5a4 100644
--- a/tests/field_defaults/models.py
+++ b/tests/field_defaults/models.py
@@ -12,6 +12,8 @@ field.
 from datetime import datetime
 
 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):
@@ -20,3 +22,45 @@ class Article(models.Model):
 
     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())
+
+    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
+    )