Merge pull request #2204 from Pacu2/2203/ability-to-compare-q-objects

Add __eq__ to Q and Q operations

AUTHORS

@@ -252,3 +252,4 @@ that much better:
  * Paulo Amaral (https://github.com/pauloAmaral)
  * Gaurav Dadhania (https://github.com/GVRV)
  * Yurii Andrieiev (https://github.com/yandrieiev)
+ * Filip Kucharczyk (https://github.com/Pacu2)

docs/changelog.rst

@@ -23,6 +23,7 @@ Development
 - Switch from nosetest to pytest as test runner #2114
 - The codebase is now formatted using ``black``. #2109
 - In bulk write insert, the detailed error message would raise in exception.
+- Added ability to compare Q and Q operations #2204
 
 Changes in 0.18.2
 =================

mongoengine/queryset/visitor.py

@@ -96,9 +96,11 @@ class QNode(object):
         """Combine this node with another node into a QCombination
         object.
         """
+        # If the other Q() is empty, ignore it and just use `self`.
         if getattr(other, "empty", True):
             return self
 
+        # Or if this Q is empty, ignore it and just use `other`.
         if self.empty:
             return other
 
@@ -146,6 +148,13 @@ class QCombination(QNode):
     def empty(self):
         return not bool(self.children)
 
+    def __eq__(self, other):
+        return (
+            self.__class__ == other.__class__
+            and self.operation == other.operation
+            and self.children == other.children
+        )
+
 
 class Q(QNode):
     """A simple query object, used in a query tree to build up more complex
@@ -164,3 +173,6 @@ class Q(QNode):
     @property
     def empty(self):
         return not bool(self.query)
+
+    def __eq__(self, other):
+        return self.__class__ == other.__class__ and self.query == other.query

tests/document/test_instance.py

@@ -3644,7 +3644,7 @@ class TestInstance(MongoDBTestCase):
             User.objects().select_related()
 
     def test_embedded_document_failed_while_loading_instance_when_it_is_not_a_dict(
-        self
+        self,
     ):
         class LightSaber(EmbeddedDocument):
             color = StringField()

tests/queryset/test_visitor.py

@@ -374,6 +374,39 @@ class TestQ(unittest.TestCase):
             == 2
         )
 
+    def test_equality(self):
+        assert Q(name="John") == Q(name="John")
+        assert Q() == Q()
+
+    def test_inequality(self):
+        assert Q(name="John") != Q(name="Ralph")
+
+    def test_operation_equality(self):
+        q1 = Q(name="John") | Q(title="Sir") & Q(surname="Paul")
+        q2 = Q(name="John") | Q(title="Sir") & Q(surname="Paul")
+        assert q1 == q2
+
+    def test_operation_inequality(self):
+        q1 = Q(name="John") | Q(title="Sir")
+        q2 = Q(title="Sir") | Q(name="John")
+        assert q1 != q2
+
+    def test_combine_and_empty(self):
+        q = Q(x=1)
+        assert q & Q() == q
+        assert Q() & q == q
+
+    def test_combine_and_both_empty(self):
+        assert Q() & Q() == Q()
+
+    def test_combine_or_empty(self):
+        q = Q(x=1)
+        assert q | Q() == q
+        assert Q() | q == q
+
+    def test_combine_or_both_empty(self):
+        assert Q() | Q() == Q()
+
 
 if __name__ == "__main__":
     unittest.main()