Keep wildcard keys when a mapped value is null or empty

CHANGELOG.rst

@@ -46,6 +46,7 @@ Bug Fixes
 ::
 
    * Adjust field tests for Python 3.14 (``staticmethod`` around ``functools.partial`` used as a class attribute). [python-restx]
+   * Keep later wildcard keys when a mapped value is null or an empty list (#409, #283) [Cherith1222]
 
 .. _section-1.3.1:
 1.3.1

flask_restx/fields.py

@@ -819,9 +819,13 @@ class Wildcard(Raw):
     _obj = None
     _cache = set()
     _last = None
+    # True once output() has no further matching key. A mapped value of
+    # None or [] is still a real value and must not set this.
+    _exhausted = False
 
     def __init__(self, cls_or_instance, **kwargs):
         super(Wildcard, self).__init__(**kwargs)
+        self._exhausted = False
         error_msg = "The type of the wildcard elements must be a subclass of fields.Raw"
         if isinstance(cls_or_instance, type):
             if not issubclass(cls_or_instance, Raw):
@@ -866,9 +870,11 @@ def reset(self):
         self._obj = None
         self._cache = set()
         self._last = None
+        self._exhausted = False
 
     def output(self, key, obj, ordered=False):
         value = None
+        found = False
         reg = fnmatch.translate(key)
 
         if self._flatten(obj):
@@ -889,12 +895,16 @@ def output(self, key, obj, ordered=False):
                         and re.match(reg, objkey, re.IGNORECASE)
                     ):
                         value = val
+                        found = True
                         self._cache.add(objkey)
                         self._last = objkey
                         break
                 except IndexError:
                     break
 
+        # None and [] are valid mapped values. Only "no remaining key"
+        # ends the wildcard scan (see marshalling.marshal).
+        self._exhausted = not found
         if value is None:
             if self.default is not None:
                 return self.container.format(self.default)

flask_restx/marshalling.py

@@ -82,11 +82,9 @@ def _append(k, v):
 
                     key = field.key or dkey
                     _append(key, value)
-                    while True:
+                    while not field._exhausted:
                         value = field.output(dkey, data, ordered=ordered)
-                        if value is None or value == field.container.format(
-                            field.default
-                        ):
+                        if field._exhausted:
                             break
                         key = field.key
                         _append(key, value)

tests/test_marshalling.py

@@ -93,6 +93,51 @@ def test_marshal_wildcard_with_skip_none(self):
         output = marshal(marshal_dict, model, skip_none=True)
         assert output == {"baz": "biz"}
 
+    def test_marshal_wildcard_keeps_null_and_later_keys(self):
+        # A null value used to end the scan, dropping every key not yet visited.
+        wild = fields.Wildcard(fields.String)
+        model = {"*": wild}
+        data = {"a": 1, "b": "2", "c": None, "d": 20, "e": "e"}
+        assert marshal(data, model) == {
+            "a": "1",
+            "b": "2",
+            "c": None,
+            "d": "20",
+            "e": "e",
+        }
+        assert marshal(data, model, skip_none=True) == {
+            "a": "1",
+            "b": "2",
+            "d": "20",
+            "e": "e",
+        }
+        ordered = marshal(data, model, ordered=True)
+        assert list(ordered) == ["a", "b", "c", "d", "e"]
+
+    def test_marshal_wildcard_keeps_empty_lists(self):
+        # List.format(None) is [], so an empty list compared equal to the
+        # "no more keys" sentinel and stopped the scan.
+        wild = fields.Wildcard(fields.List(fields.String))
+        model = {"*": wild}
+        data = {"a": ["1"], "b": [], "c": ["3"]}
+        assert marshal(data, model) == {"a": ["1"], "b": [], "c": ["3"]}
+
+        nested = {"id": fields.String(), "name": fields.String()}
+        wild_list = fields.Wildcard(fields.List(fields.Nested(nested)))
+        payload = {
+            "listMap": {
+                "key7": [{"id": "1", "name": "Guido"}],
+                "key8": [],
+                "key9": [{"id": "3", "name": "Linus"}],
+            }
+        }
+        output = marshal(payload, {"listMap": fields.Nested({"*": wild_list})})
+        assert output["listMap"] == {
+            "key7": [{"id": "1", "name": "Guido"}],
+            "key8": [],
+            "key9": [{"id": "3", "name": "Linus"}],
+        }
+
     def test_marshal_decorator(self):
         model = OrderedDict([("foo", fields.Raw)])