check for required properties before put

src/google/cloud/ndb/model.py

@@ -614,8 +614,12 @@ def _entity_to_ds_entity(entity, set_key=True):
 
     Returns:
         google.cloud.datastore.entity.Entity: The converted entity.
+
+    Raises:
+        ndb.exceptions.BadValueError: If entity has uninitialized properties.
     """
     data = {}
+    uninitialized = []
     exclude_from_indexes = []
 
     for cls in type(entity).mro():
@@ -630,6 +634,9 @@ def _entity_to_ds_entity(entity, set_key=True):
             ):
                 continue
 
+            if not prop._is_initialized(entity):
+                uninitialized.append(prop._name)
+
             value = prop._get_base_value_unwrapped_as_list(entity)
             if not prop._repeated:
                 value = value[0]
@@ -638,6 +645,12 @@ def _entity_to_ds_entity(entity, set_key=True):
             if not prop._indexed:
                 exclude_from_indexes.append(prop._name)
 
+    if uninitialized:
+        names = ", ".join(uninitialized)
+        raise exceptions.BadValueError(
+            "Entity has uninitialized properties: {}".format(names)
+        )
+
     ds_entity = None
     if set_key:
         key = entity._key

tests/system/test_crud.py

@@ -600,3 +600,14 @@ class SomeKind(ndb.Model):
     assert isinstance(retrieved.updated_at, datetime.datetime)
 
     dispose_of(key._key)
+
+
+@pytest.mark.usefixtures("client_context")
+def test_uninitialized_property(dispose_of):
+    class SomeKind(ndb.Model):
+        foo = ndb.StringProperty(required=True)
+
+    entity = SomeKind()
+
+    with pytest.raises(ndb.exceptions.BadValueError):
+        entity.put()

tests/unit/test_model.py

@@ -4542,6 +4542,17 @@ class ThisKind(ThatKind):
         assert pickle.loads(e_values[1].blob_value) == dill
         assert "__key__" not in entity_pb.properties
 
+    @staticmethod
+    @pytest.mark.usefixtures("in_context")
+    def test_uninitialized_property():
+        class ThisKind(model.Model):
+            foo = model.StringProperty(required=True)
+
+        entity = ThisKind()
+
+        with pytest.raises(exceptions.BadValueError):
+            model._entity_to_protobuf(entity)
+
 
 class TestExpando:
     @staticmethod