Ticket #17186: invert.f-2.patch

tests/modeltests/expressions/tests.py

@@ -22 +22 @@
             ceo=Employee.objects.create(firstname="Max", lastname="Mustermann")
         )
 
+        # mark acttive employees when their companys have num_chairs great that 3
+        employee_qs = Employee.objects.filter(is_active=False)
+        self.assertEqual(employee_qs.count(), 3)
+
+        Employee.objects.filter(company_ceo_set__num_chairs__gte=3)\
+            .update(is_active=~F("is_active"))
+
+        employee_qs = Employee.objects.filter(is_active=False)
+        self.assertEqual(employee_qs.count(), 1)
+
         company_query = Company.objects.values(
             "name", "num_employees", "num_chairs"
         ).order_by(

tests/modeltests/expressions/models.py

@@ -8 +8 @@
 class Employee(models.Model):
     firstname = models.CharField(max_length=50)
     lastname = models.CharField(max_length=50)
+    is_active = models.BooleanField(default=False)
 
     def __unicode__(self):
         return u'%s %s' % (self.firstname, self.lastname)
@@ -26 +27 @@
 
     def __unicode__(self):
         return self.name
+
+

django/db/models/expressions.py

@@ -98 +98 @@
     """
     An expression representing the value of the given field.
     """
+
+    _invert = False
+
     def __init__(self, name):
         super(F, self).__init__(None, None, False)
         self.name = name
@@ -107 +110 @@
         obj.name = self.name
         return obj
 
+    def __invert__(self):
+        self._invert = True
+        return self
+
     def prepare(self, evaluator, query, allow_joins):
         return evaluator.prepare_leaf(self, query, allow_joins)
 
     def evaluate(self, evaluator, qn, connection):
-        return evaluator.evaluate_leaf(self, qn, connection)
+        evresult = list(evaluator.evaluate_leaf(self, qn, connection))
+        if self._invert:
+            evresult[0] = "NOT %s" % evresult[0]
+        return tuple(evresult)
 
+
 class DateModifierNode(ExpressionNode):
     """
     Node that implements the following syntax: