From b881bde5027ba3f49f010afc633b48aaf53aa272 Mon Sep 17 00:00:00 2001
From: "T. Franzel" <tfranzel@users.noreply.github.com>
Date: Thu, 10 Jun 2021 22:57:42 +0200
Subject: [PATCH] serializer field deprecation #415

---
 drf_spectacular/openapi.py |  3 +++
 drf_spectacular/utils.py   |  4 ++++
 tests/test_regressions.py  | 18 ++++++++++++++++++
 3 files changed, 25 insertions(+)

diff --git a/drf_spectacular/openapi.py b/drf_spectacular/openapi.py
index 971a3ba8..66bf3cf8 100644
--- a/drf_spectacular/openapi.py
+++ b/drf_spectacular/openapi.py
@@ -771,6 +771,9 @@ def _map_basic_serializer(self, serializer, direction):
 
             self._map_field_validators(field, schema)
 
+            if field.field_name in get_override(serializer, 'deprecate_fields', []):
+                schema['deprecated'] = True
+
             properties[field.field_name] = safe_ref(schema)
 
         if is_patched_serializer(serializer, direction):
diff --git a/drf_spectacular/utils.py b/drf_spectacular/utils.py
index a10b2c89..24cf2db2 100644
--- a/drf_spectacular/utils.py
+++ b/drf_spectacular/utils.py
@@ -392,6 +392,7 @@ def decorator(f):
 def extend_schema_serializer(
         many: Optional[bool] = None,
         exclude_fields: Optional[List[str]] = None,
+        deprecate_fields: Optional[List[str]] = None,
         examples: Optional[List[OpenApiExample]] = None,
 ):
     """
@@ -402,6 +403,7 @@ def extend_schema_serializer(
         heuristic to acknowledge a non-list serializer.
     :param exclude_fields: fields to ignore while processing the serializer. only affects the
         schema. fields will still be exposed through the API.
+    :param deprecate_fields: fields to mark as deprecated while processing the serializer.
     :param examples: define example data to serializer.
     """
     def decorator(klass):
@@ -409,6 +411,8 @@ def decorator(klass):
             set_override(klass, 'many', many)
         if exclude_fields:
             set_override(klass, 'exclude_fields', exclude_fields)
+        if deprecate_fields:
+            set_override(klass, 'deprecate_fields', deprecate_fields)
         if examples:
             set_override(klass, 'examples', examples)
         return klass
diff --git a/tests/test_regressions.py b/tests/test_regressions.py
index c5795a72..f75acceb 100644
--- a/tests/test_regressions.py
+++ b/tests/test_regressions.py
@@ -1992,3 +1992,21 @@ class XViewset(viewsets.ReadOnlyModelViewSet):
         'items': {'type': 'array', 'items': {'type': 'integer'}, 'readOnly': True},
         'readOnly': True
     }
+
+
+def test_extend_schema_serializer_field_deprecation(no_warnings):
+    @extend_schema_serializer(deprecate_fields=['old'])
+    class XSerializer(serializers.Serializer):
+        old = serializers.IntegerField()
+        new = serializers.IntegerField()
+
+    class XView(generics.ListCreateAPIView):
+        serializer_class = XSerializer
+
+    schema = generate_schema('/x', view=XView)
+    assert schema['components']['schemas']['X']['properties']['new'] == {
+        'type': 'integer',
+    }
+    assert schema['components']['schemas']['X']['properties']['old'] == {
+        'type': 'integer', 'deprecated': True
+    }