Nested allow_none=True implementation

marshmallow_jsonschema/base.py

@@ -241,7 +241,7 @@ def _from_nested_schema(self, obj, field):
  self._nested_schema_classes.update(wrapped_nested._nested_schema_classes)
 
  # and the schema is just a reference to the def
- schema = {"type": "object", "$ref": "#/definitions/{}".format(name)}
+ schema = {"$ref": "#/definitions/{}".format(name)}
 
  # NOTE: doubled up to maintain backwards compatibility
  metadata = field.metadata.get("metadata", {})
@@ -252,6 +252,14 @@ def _from_nested_schema(self, obj, field):
  continue
  schema[md_key] = md_val
 
+ if field.allow_none:
+ schema = {
+ "anyOf": [
+ schema, 
+ {"type": "null"}
+ ]
+ }
+
  if field.many:
  schema = {
  "type": "array" if field.required else ["array", "null"],

tests/test_dump.py

@@ -102,7 +102,6 @@ class TestSchema(Schema):
 
  nested_def = dumped["definitions"]["TestNamedNestedSchema"]
  nested_dmp = dumped["definitions"]["TestSchema"]["properties"]["nested"]
- assert nested_dmp["type"] == "object"
  assert nested_def["properties"]["foo"]["format"] == "integer"
 
 
@@ -416,6 +415,27 @@ class TestSchema(Schema):
  }
 
 
+def test_allow_none_on_nested():
+ """A Nested field with allow_none set to True should result in anyOf"""
+ class ChildSchema(Schema):
+ id = fields.Integer(required=True)
+
+ class TestSchema(Schema):
+ id = fields.Integer(required=True)
+ nested_fld = fields.Nested(ChildSchema, allow_none=True)
+
+ schema = TestSchema()
+
+ dumped = validate_and_dump(schema)
+
+ assert dumped["definitions"]["TestSchema"]["properties"]["nested_fld"] == {
+ "anyOf": [
+ {'$ref': '#/definitions/ChildSchema'},
+ {"type": "null"}
+ ]
+ }
+
+
 def test_dumps_iterable_enums():
  mapping = {"a": 0, "b": 1, "c": 2}