From d58604f273485d0a44d5f32c419d3ce5807813f6 Mon Sep 17 00:00:00 2001
From: Melvin Koh <melvinkcx@gmail.com>
Date: Mon, 23 Dec 2024 05:54:48 -0500
Subject: [PATCH] Add support for dynamic serializer fields (#109)

---
 drf_excel/renderers.py       |  4 ++--
 tests/test_viewset_mixin.py  | 16 ++++++++++++++++
 tests/testapp/serializers.py | 12 ++++++++++++
 tests/testapp/views.py       | 29 +++++++++++++++++++++++++++--
 tests/urls.py                |  8 +++++++-
 5 files changed, 64 insertions(+), 5 deletions(-)

diff --git a/drf_excel/renderers.py b/drf_excel/renderers.py
index ba29313..002d7ba 100644
--- a/drf_excel/renderers.py
+++ b/drf_excel/renderers.py
@@ -241,7 +241,7 @@ def _check_validation_data(self, data):
 
     def _serializer_fields(self, serializer, parent_key="", key_sep="."):
         _fields_dict = {}
-        for k, v in serializer.get_fields().items():
+        for k, v in serializer.fields.items():
             new_key = f"{parent_key}{key_sep}{k}" if parent_key else k
             if isinstance(v, Serializer):
                 _fields_dict.update(self._serializer_fields(v, new_key, key_sep))
@@ -274,7 +274,7 @@ def _get_label(parent_label, label_sep, obj):
                 return False
 
         _header_dict = {}
-        _fields = serializer.get_fields()
+        _fields = serializer.fields
         for k, v in _fields.items():
             new_key = f"{parent_key}{key_sep}{k}" if parent_key else k
             # Skip headers we want to ignore
diff --git a/tests/test_viewset_mixin.py b/tests/test_viewset_mixin.py
index 7799258..31b2911 100644
--- a/tests/test_viewset_mixin.py
+++ b/tests/test_viewset_mixin.py
@@ -110,3 +110,19 @@ def test_secret_field_viewset(api_client, workbook_reader):
     # Check that the secret field is not included in the header or data
     assert [col.value for col in header] == ["title"]
     assert [col.value for col in data] == ["foo"]
+
+
+def test_dynamic_field_viewset(api_client, workbook_reader):
+    response = api_client.get("/dynamic-field/")
+    assert response.status_code == 200
+
+    wb = workbook_reader(response.content)
+    sheet = wb.worksheets[0]
+
+    header, data = list(sheet.rows)
+
+    header_values = [cell.value for cell in header]
+    assert header_values == ["field_1", "field_2", "field_99", "field_98"]
+
+    row_1_values = [cell.value for cell in data]
+    assert row_1_values == ["YUL", "CDG", "YYZ", "MAR"]
diff --git a/tests/testapp/serializers.py b/tests/testapp/serializers.py
index e433822..e3f70b6 100644
--- a/tests/testapp/serializers.py
+++ b/tests/testapp/serializers.py
@@ -33,3 +33,15 @@ class Meta:
         fields = ("title", "secret", "secret_external")
 
         extra_kwargs = {"secret": {"write_only": True}}
+
+
+class DynamicFieldSerializer(serializers.Serializer):
+    field_1 = serializers.CharField()
+    field_2 = serializers.CharField()
+
+    def __init__(self, *args, **kwargs):
+        super().__init__(*args, **kwargs)
+
+        # Fields can be added dynamically
+        self.fields["field_99"] = serializers.CharField()
+        self.fields["field_98"] = serializers.CharField()
diff --git a/tests/testapp/views.py b/tests/testapp/views.py
index 71b7038..77c43a8 100644
--- a/tests/testapp/views.py
+++ b/tests/testapp/views.py
@@ -1,10 +1,16 @@
-from rest_framework.viewsets import ReadOnlyModelViewSet
+from rest_framework.response import Response
+from rest_framework.viewsets import GenericViewSet, ReadOnlyModelViewSet
 
 from drf_excel.mixins import XLSXFileMixin
 from drf_excel.renderers import XLSXRenderer
 
 from .models import AllFieldsModel, ExampleModel, SecretFieldModel
-from .serializers import AllFieldsSerializer, ExampleSerializer, SecretFieldSerializer
+from .serializers import (
+    AllFieldsSerializer,
+    DynamicFieldSerializer,
+    ExampleSerializer,
+    SecretFieldSerializer,
+)
 
 
 class ExampleViewSet(XLSXFileMixin, ReadOnlyModelViewSet):
@@ -26,3 +32,22 @@ class SecretFieldViewSet(XLSXFileMixin, ReadOnlyModelViewSet):
     serializer_class = SecretFieldSerializer
     renderer_classes = (XLSXRenderer,)
     filename = "secret.xlsx"
+
+
+class DynamicFieldViewSet(XLSXFileMixin, GenericViewSet):
+    serializer_class = DynamicFieldSerializer
+    renderer_classes = (XLSXRenderer,)
+    filename = "dynamic_field.xlsx"
+
+    def list(self, request, *args, **kwargs):
+        serializer = self.get_serializer(
+            data={
+                "field_1": "YUL",
+                "field_2": "CDG",
+                "field_55": "LHR",
+                "field_98": "MAR",
+                "field_99": "YYZ",
+            }
+        )
+        serializer.is_valid(raise_exception=True)
+        return Response(serializer.data)
diff --git a/tests/urls.py b/tests/urls.py
index d875c66..8eadca0 100644
--- a/tests/urls.py
+++ b/tests/urls.py
@@ -1,10 +1,16 @@
 from rest_framework import routers
 
-from .testapp.views import AllFieldsViewSet, ExampleViewSet, SecretFieldViewSet
+from .testapp.views import (
+    AllFieldsViewSet,
+    DynamicFieldViewSet,
+    ExampleViewSet,
+    SecretFieldViewSet,
+)
 
 router = routers.SimpleRouter()
 router.register(r"examples", ExampleViewSet)
 router.register(r"all-fields", AllFieldsViewSet)
 router.register(r"secret-field", SecretFieldViewSet)
+router.register(r"dynamic-field", DynamicFieldViewSet, basename="dynamic-field")
 
 urlpatterns = router.urls