Ticket #17186: invert.f.patch

db/models/expressions.py

@@ -98 +98 @@
     """
     An expression representing the value of the given field.
     """
+
+    self._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: