Refs #11964 -- Made Q objects deconstructible.

django/db/models/query_utils.py

@@ -56,7 +56,9 @@ class Q(tree.Node):
     default = AND
 
     def __init__(self, *args, **kwargs):
-        super().__init__(children=list(args) + list(kwargs.items()))
+        connector = kwargs.pop('_connector', None)
+        negated = kwargs.pop('_negated', False)
+        super().__init__(children=list(args) + list(kwargs.items()), connector=connector, negated=negated)
 
     def _combine(self, other, conn):
         if not isinstance(other, Q):
@@ -86,6 +88,19 @@ class Q(tree.Node):
         query.promote_joins(joins)
         return clause
 
+    def deconstruct(self):
+        path = '%s.%s' % (self.__class__.__module__, self.__class__.__name__)
+        args, kwargs = (), {}
+        if len(self.children) == 1 and not isinstance(self.children[0], Q):
+            child = self.children[0]
+            kwargs = {child[0]: child[1]}
+        else:
+            args = tuple(self.children)
+            kwargs = {'_connector': self.connector}
+        if self.negated:
+            kwargs['_negated'] = True
+        return path, args, kwargs
+
 
 class DeferredAttribute:
     """

django/utils/tree.py

@@ -63,6 +63,13 @@ class Node:
         """Return True if 'other' is a direct child of this instance."""
         return other in self.children
 
+    def __eq__(self, other):
+        if self.__class__ != other.__class__:
+            return False
+        if (self.connector, self.negated) == (other.connector, other.negated):
+            return self.children == other.children
+        return False
+
     def add(self, data, conn_type, squash=True):
         """
         Combine this tree and the data represented by data using the

tests/queries/test_q.py

@@ -0,0 +1,76 @@
+from django.db.models import F, Q
+from django.test import SimpleTestCase
+
+
+class QTests(SimpleTestCase):
+    def test_deconstruct(self):
+        q = Q(price__gt=F('discounted_price'))
+        path, args, kwargs = q.deconstruct()
+        self.assertEqual(path, 'django.db.models.query_utils.Q')
+        self.assertEqual(args, ())
+        self.assertEqual(kwargs, {'price__gt': F('discounted_price')})
+
+    def test_deconstruct_negated(self):
+        q = ~Q(price__gt=F('discounted_price'))
+        path, args, kwargs = q.deconstruct()
+        self.assertEqual(path, 'django.db.models.query_utils.Q')
+        self.assertEqual(args, ())
+        self.assertEqual(kwargs, {
+            'price__gt': F('discounted_price'),
+            '_negated': True,
+        })
+
+    def test_deconstruct_or(self):
+        q1 = Q(price__gt=F('discounted_price'))
+        q2 = Q(price=F('discounted_price'))
+        q = q1 | q2
+        path, args, kwargs = q.deconstruct()
+        self.assertEqual(path, 'django.db.models.query_utils.Q')
+        self.assertEqual(args, (
+            ('price__gt', F('discounted_price')),
+            ('price', F('discounted_price')),
+        ))
+        self.assertEqual(kwargs, {'_connector': 'OR'})
+
+    def test_deconstruct_and(self):
+        q1 = Q(price__gt=F('discounted_price'))
+        q2 = Q(price=F('discounted_price'))
+        q = q1 & q2
+        path, args, kwargs = q.deconstruct()
+        self.assertEqual(path, 'django.db.models.query_utils.Q')
+        self.assertEqual(args, (
+            ('price__gt', F('discounted_price')),
+            ('price', F('discounted_price')),
+        ))
+        self.assertEqual(kwargs, {'_connector': 'AND'})
+
+    def test_deconstruct_nested(self):
+        q = Q(Q(price__gt=F('discounted_price')))
+        path, args, kwargs = q.deconstruct()
+        self.assertEqual(path, 'django.db.models.query_utils.Q')
+        self.assertEqual(args, (Q(price__gt=F('discounted_price')),))
+        self.assertEqual(kwargs, {'_connector': 'AND'})
+
+    def test_reconstruct(self):
+        q = Q(price__gt=F('discounted_price'))
+        path, args, kwargs = q.deconstruct()
+        self.assertEqual(Q(*args, **kwargs), q)
+
+    def test_reconstruct_negated(self):
+        q = ~Q(price__gt=F('discounted_price'))
+        path, args, kwargs = q.deconstruct()
+        self.assertEqual(Q(*args, **kwargs), q)
+
+    def test_reconstruct_or(self):
+        q1 = Q(price__gt=F('discounted_price'))
+        q2 = Q(price=F('discounted_price'))
+        q = q1 | q2
+        path, args, kwargs = q.deconstruct()
+        self.assertEqual(Q(*args, **kwargs), q)
+
+    def test_reconstruct_and(self):
+        q1 = Q(price__gt=F('discounted_price'))
+        q2 = Q(price=F('discounted_price'))
+        q = q1 & q2
+        path, args, kwargs = q.deconstruct()
+        self.assertEqual(Q(*args, **kwargs), q)

tests/utils_tests/test_tree.py

@@ -55,3 +55,19 @@ class NodeTests(unittest.TestCase):
         node5 = copy.deepcopy(self.node1)
         self.assertIs(self.node1.children, node4.children)
         self.assertIsNot(self.node1.children, node5.children)
+
+    def test_eq_children(self):
+        node = Node(self.node1_children)
+        self.assertEqual(node, self.node1)
+        self.assertNotEqual(node, self.node2)
+
+    def test_eq_connector(self):
+        new_node = Node(connector='NEW')
+        default_node = Node(connector='DEFAULT')
+        self.assertEqual(default_node, self.node2)
+        self.assertNotEqual(default_node, new_node)
+
+    def test_eq_negated(self):
+        node = Node(negated=False)
+        negated = Node(negated=True)
+        self.assertNotEqual(negated, node)