From dc1db5d498c04c4a7dc92383747fabf68c01e6a6 Mon Sep 17 00:00:00 2001
From: Mike Reiss <mreiss@teikametrics.com>
Date: Fri, 12 Mar 2021 13:48:05 -0500
Subject: [PATCH] Skip response fields where value is None

---
 flask_accepts/decorators/decorators.py      | 16 ++++++++
 flask_accepts/decorators/decorators_test.py | 43 +++++++++++++++++++++
 2 files changed, 59 insertions(+)

diff --git a/flask_accepts/decorators/decorators.py b/flask_accepts/decorators/decorators.py
index 4b0bf89..c6f334b 100644
--- a/flask_accepts/decorators/decorators.py
+++ b/flask_accepts/decorators/decorators.py
@@ -207,6 +207,7 @@ def responds(
     validate: bool = False,
     description: str = None,
     use_swagger: bool = True,
+    skip_none: bool = False,
 ):
     """
     Serialize the output of a function using the Marshmallow schema to dump the results.
@@ -285,6 +286,21 @@ def inner(*args, **kwargs):
             if envelope:
                 serialized = OrderedDict([(envelope, serialized)]) if ordered else {envelope: serialized}
 
+            if skip_none:
+                def remove_none(obj):
+                    if isinstance(obj, list):
+                        return [remove_none(entry) for entry in obj if entry is not None]
+                    if isinstance(obj, dict):
+                        result = {}
+                        for key, value in obj.items():
+                            value = remove_none(value)
+                            if key is not None and value is not None:
+                                result[key] = value
+                        return result
+                    return obj
+
+                serialized = remove_none(serialized)
+
             if not _is_method(func):
                 # Regular route, need to manually create Response
                 return jsonify(serialized), status_code
diff --git a/flask_accepts/decorators/decorators_test.py b/flask_accepts/decorators/decorators_test.py
index ce239ab..8e3da83 100644
--- a/flask_accepts/decorators/decorators_test.py
+++ b/flask_accepts/decorators/decorators_test.py
@@ -626,6 +626,49 @@ def get(self):
         assert resp.status_code == 200
         assert resp.json == {'test-data': {'_id': 42, 'name': 'Jon Snow'}}
 
+
+def test_responds_skips_none_false(app, client):
+    class TestSchema(Schema):
+        _id = fields.Integer()
+        name = fields.String()
+
+    api = Api(app)
+
+    @api.route("/test")
+    class TestResource(Resource):
+        @responds(schema=TestSchema, api=api)
+        def get(self):
+            return {"_id": 42, "name": None}
+
+    with client as cl:
+        resp = cl.get("/test")
+        assert resp.status_code == 200
+        assert resp.json == {'_id': 42, 'name': None}
+
+
+def test_responds_with_nested_skips_none_true(app, client):
+    class NestSchema(Schema):
+        _id = fields.Integer()
+        name = fields.String()
+
+    class TestSchema(Schema):
+        name = fields.String()
+        child = fields.Nested(NestSchema)
+
+    api = Api(app)
+
+    @api.route("/test")
+    class TestResource(Resource):
+        @responds(schema=TestSchema, api=api, skip_none=True, many=True)
+        def get(self):
+            return [{"name": None, "child": {"_id": 42, "name": None}}]
+
+    with client as cl:
+        resp = cl.get("/test")
+        assert resp.status_code == 200
+        assert resp.json == [{"child": {'_id': 42}}]
+
+
 def test_accepts_with_nested_schema(app, client):  # noqa
     class TestSchema(Schema):
         _id = fields.Integer()