From 9cec57e09267747b1d2ec66c3d1e23ab5f3b57d5 Mon Sep 17 00:00:00 2001
From: Rob van Diepen <rob.vandiepen@agriplace.com>
Date: Wed, 4 Oct 2023 12:24:43 +0200
Subject: [PATCH 1/2] Support nullable ListFields with django-rest-framework

---
 drf_excel/fields.py | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drf_excel/fields.py b/drf_excel/fields.py
index 2cbd16c..4caca58 100644
--- a/drf_excel/fields.py
+++ b/drf_excel/fields.py
@@ -159,7 +159,9 @@ def __init__(self, list_sep, **kwargs):
         super().__init__(**kwargs)
 
     def prep_value(self) -> Any:
-        if len(self.value) > 0 and isinstance(self.value[0], Iterable):
+        if self.value is None:
+            return super().prep_value()
+        elif len(self.value) > 0 and isinstance(self.value[0], Iterable):
             # array of array; write as json
             return json.dumps(self.value, ensure_ascii=False)
         else:

From 65e8874e12b64d653376d27f32599c3f9842d653 Mon Sep 17 00:00:00 2001
From: Bruno Alla <alla.brunoo@gmail.com>
Date: Fri, 11 Oct 2024 20:59:24 +0100
Subject: [PATCH 2/2] Expand test suite to cover null and empty list values in
 XLSXListField

---
 tests/test_fields.py | 30 ++++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)

diff --git a/tests/test_fields.py b/tests/test_fields.py
index 0789d00..112e09c 100644
--- a/tests/test_fields.py
+++ b/tests/test_fields.py
@@ -444,6 +444,36 @@ def test_cell_complex_types(self, style: XLSXStyle, worksheet: Worksheet):
         assert isinstance(cell, Cell)
         assert cell.value == '[{"a": 1}, {"b": 2}]'
 
+    def test_cell_with_empty_list(self, style: XLSXStyle, worksheet: Worksheet):
+        f = XLSXListField(
+            list_sep=None,
+            key="objs",
+            value=[],
+            field=ListField(),
+            style=style,
+            mapping="",
+            cell_style=style,
+        )
+        assert f.original_value == f.value == []
+        cell = f.cell(worksheet, 1, 1)
+        assert isinstance(cell, Cell)
+        assert cell.value == ""
+
+    def test_cell_with_null_value(self, style: XLSXStyle, worksheet: Worksheet):
+        f = XLSXListField(
+            list_sep=None,
+            key="objs",
+            value=None,
+            field=ListField(allow_null=True),
+            style=style,
+            mapping="",
+            cell_style=style,
+        )
+        assert f.original_value is f.value is None
+        cell = f.cell(worksheet, 1, 1)
+        assert isinstance(cell, Cell)
+        assert cell.value is None
+
 
 class TestXLSXBooleanField:
     @pytest.mark.parametrize("value", [True, False])