5.x: propagate null_check to maps in lists (#1128)

When calling `model.serialize(null_check=False)`, we were propagating `null_check=False` to maps (and maps nested in maps), but not maps nested in lists.

Backport of #1127 to 5.x branch.

.github/workflows/test.yaml

@@ -8,7 +8,7 @@ on:
 jobs:
   test:
 
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-20.04
     strategy:
       matrix:
         python-version: ['3.6', '3.7', '3.8', 'pypy-3.6']

docs/release_notes.rst

@@ -3,6 +3,11 @@
 Release Notes
 =============
 
+v5.3.4
+----------
+* Make serialization :code:`null_check=False` propagate to maps inside lists (#1128).
+
+
 v5.3.3
 ----------
 * Fix :py:class:`~pynamodb.pagination.PageIterator` and :py:class:`~pynamodb.pagination.ResultIterator`

pynamodb/__init__.py

@@ -7,4 +7,4 @@
 """
 __author__ = 'Jharrod LaFon'
 __license__ = 'MIT'
-__version__ = '5.3.3'
+__version__ = '5.3.4'

pynamodb/attributes.py

@@ -352,7 +352,7 @@ def _container_serialize(self, null_check: bool = True) -> Dict[str, Dict[str, A
                 raise
 
             if value is not None:
-                if isinstance(attr, MapAttribute):
+                if isinstance(attr, (ListAttribute, MapAttribute)):
                     attr_value = attr.serialize(value, null_check=null_check)
                 else:
                     attr_value = attr.serialize(value)
@@ -1123,7 +1123,7 @@ def __init__(
                 raise ValueError("'of' must be a subclass of Attribute")
             self.element_type = of
 
-    def serialize(self, values):
+    def serialize(self, values, *, null_check: bool = True):
         """
         Encode the given list of objects into a list of AttributeValue types.
         """
@@ -1133,7 +1133,10 @@ def serialize(self, values):
             if self.element_type and v is not None and not isinstance(attr_class, self.element_type):
                 raise ValueError("List elements must be of type: {}".format(self.element_type.__name__))
             attr_type = attr_class.attr_type
-            attr_value = attr_class.serialize(v)
+            if isinstance(attr_class, (ListAttribute, MapAttribute)):
+                attr_value = attr_class.serialize(v, null_check=null_check)
+            else:
+                attr_value = attr_class.serialize(v)
             if attr_value is None:
                 # When attribute values serialize to "None" (e.g. empty sets) we store {"NULL": True} in DynamoDB.
                 attr_type = NULL

tests/test_model.py

@@ -391,29 +391,29 @@ class Meta:
     is_human = BooleanAttribute()
 
 
-class TreeLeaf2(MapAttribute):
+class TreeLeaf(MapAttribute):
     value = NumberAttribute()
 
 
-class TreeLeaf1(MapAttribute):
+class TreeNode2(MapAttribute):
     value = NumberAttribute()
-    left = TreeLeaf2()
-    right = TreeLeaf2()
+    left = TreeLeaf()
+    right = TreeLeaf()
 
 
-class TreeLeaf(MapAttribute):
+class TreeNode1(MapAttribute):
     value = NumberAttribute()
-    left = TreeLeaf1()
-    right = TreeLeaf1()
+    left = TreeNode2()
+    right = TreeNode2()
 
 
 class TreeModel(Model):
     class Meta:
         table_name = 'TreeModelTable'
 
     tree_key = UnicodeAttribute(hash_key=True)
-    left = TreeLeaf()
-    right = TreeLeaf()
+    left = TreeNode1()
+    right = TreeNode1()
 
 
 class ExplicitRawMapModel(Model):
@@ -2911,41 +2911,61 @@ def test_deserializing_new_style_bool_true_works(self):
             self.assertTrue(item.is_human)
 
     def test_serializing_map_with_null_check(self):
-        item = TreeModel(
+        class TreeModelWithList(TreeModel):
+            leaves = ListAttribute(of=TreeLeaf)
+
+        item = TreeModelWithList(
             tree_key='test',
-            left=TreeLeaf(
+            left=TreeNode1(
                 value=42,
-                left=TreeLeaf1(
+                left=TreeNode2(
                     value=42,
-                    left=TreeLeaf2(value=42),
-                    right=TreeLeaf2(value=42),
+                    left=TreeLeaf(value=42),
+                    right=TreeLeaf(value=42),
                 ),
-                right=TreeLeaf1(
+                right=TreeNode2(
                     value=42,
-                    left=TreeLeaf2(value=42),
-                    right=TreeLeaf2(value=42),
+                    left=TreeLeaf(value=42),
+                    right=TreeLeaf(value=42),
                 ),
             ),
-            right=TreeLeaf(
+            right=TreeNode1(
                 value=42,
-                left=TreeLeaf1(
+                left=TreeNode2(
                     value=42,
-                    left=TreeLeaf2(value=42),
-                    right=TreeLeaf2(value=42),
+                    left=TreeLeaf(value=42),
+                    right=TreeLeaf(value=42),
                 ),
-                right=TreeLeaf1(
+                right=TreeNode2(
                     value=42,
-                    left=TreeLeaf2(value=42),
-                    right=TreeLeaf2(value=42),
+                    left=TreeLeaf(value=42),
+                    right=TreeLeaf(value=42),
                 ),
             ),
+            leaves=[
+                TreeLeaf(value=42),
+            ],
         )
         item.serialize(null_check=False)
 
         # now let's nullify an attribute a few levels deep to test that `null_check` propagates
         item.left.left.left.value = None
         item.serialize(null_check=False)
 
+        # now with null check
+        with pytest.raises(Exception, match="Attribute 'left.value' cannot be None"):
+            item.serialize(null_check=True)
+
+        # now let's nullify an attribute of a map in a list to test that `null_check` propagates
+        item.left.left.left.value = 42
+        item.leaves[0].value = None
+        item.serialize(null_check=False)
+
+        # now with null check
+        with pytest.raises(Exception, match=r"Attribute 'value' cannot be None"):
+            item.serialize(null_check=True)
+
+
     def test_deserializing_map_four_layers_deep_works(self):
         fake_db = self.database_mocker(TreeModel,
                                        TREE_MODEL_TABLE_DATA,
@@ -3401,8 +3421,8 @@ def test_subclassed_map_attribute_with_map_attributes_member_with_dict_init(self
     def test_subclassed_map_attribute_with_map_attribute_member_with_initialized_instance_init(self):
         left = self._get_bin_tree()
         right = self._get_bin_tree(multiplier=2)
-        left_instance = TreeLeaf(**left)
-        right_instance = TreeLeaf(**right)
+        left_instance = TreeNode1(**left)
+        right_instance = TreeNode1(**right)
         actual = TreeModel(tree_key='key', left=left_instance, right=right_instance)
         self.assertEqual(actual.left.left.right.value, left_instance.left.right.value)
         self.assertEqual(actual.left.left.value, left_instance.left.value)