Fixed #31410 -- Added check for fields of UniqueConstraints.

django/db/models/base.py

@@ -1926,6 +1926,9 @@ def _check_constraints(cls, databases):
                         id='models.W038',
                     )
                 )
+            for constraint in cls._meta.constraints:
+                if isinstance(constraint, UniqueConstraint):
+                    errors.extend(cls._check_local_fields(constraint.fields, "unique_constraint"))
         return errors
 
 

tests/invalid_models_tests/test_models.py

@@ -1414,6 +1414,68 @@ class Meta:
                 constraints = [models.CheckConstraint(check=models.Q(age__gte=18), name='is_adult')]
         self.assertEqual(Model.check(databases=self.databases), [])
 
+    def test_unique_constraint_pointing_to_missing_field(self):
+        class Model(models.Model):
+            class Meta:
+                constraints = [models.UniqueConstraint(fields=['missing_field'], name='name')]
+
+        self.assertEqual(Model.check(databases=self.databases), [
+            Error(
+                "'unique_constraint' refers to the nonexistent field 'missing_field'.",
+                obj=Model,
+                id='models.E012',
+            ),
+        ])
+
+    def test_unique_constraint_pointing_to_m2m_field(self):
+        class Model(models.Model):
+            m2m = models.ManyToManyField('self')
+
+            class Meta:
+                constraints = [models.UniqueConstraint(fields=['m2m'], name='name1')]
+
+        self.assertEqual(Model.check(databases=self.databases), [
+            Error(
+                "'unique_constraint' refers to a ManyToManyField 'm2m', but "
+                "ManyToManyFields are not permitted in 'unique_constraint'.",
+                obj=Model,
+                id='models.E013',
+            ),
+        ])
+
+    def test_unique_constraint_pointing_to_non_local_field(self):
+        class Foo(models.Model):
+            field1 = models.IntegerField()
+
+        class Bar(Foo):
+            field2 = models.IntegerField()
+
+            class Meta:
+                constraints = [models.UniqueConstraint(fields=['field2', 'field1'], name='name1')]
+
+        self.assertEqual(Bar.check(databases=self.databases), [
+            Error(
+                "'unique_constraint' refers to field 'field1' which is not local to "
+                "model 'Bar'.",
+                hint='This issue may be caused by multi-table inheritance.',
+                obj=Bar,
+                id='models.E016',
+            ),
+        ])
+
+    def test_unique_constraint_pointing_to_fk(self):
+        class Foo(models.Model):
+            pass
+
+        class Bar(models.Model):
+            foo_1 = models.ForeignKey(Foo, on_delete=models.CASCADE, related_name='bar_1')
+            foo_2 = models.ForeignKey(Foo, on_delete=models.CASCADE, related_name='bar_2')
+
+            class Meta:
+                constraints = [models.UniqueConstraint(fields=['foo_1_id', 'foo_2'], name='name1')]
+
+        self.assertEqual(Bar.check(databases=self.databases), [])
+
     def test_unique_constraint_with_condition(self):
         class Model(models.Model):
             age = models.IntegerField()