Fix TopoJson non-collection geometries

folium/features.py

@@ -1053,9 +1053,12 @@ def recursive_get(data, keys):
             else:
                 return data
 
-        geometries = recursive_get(self.data, self.object_path.split("."))[
-            "geometries"
-        ]  # noqa
+        geometry = recursive_get(self.data, self.object_path.split("."))
+        geometries = (
+            geometry["geometries"]
+            if geometry["type"] == "GeometryCollection"
+            else [geometry]
+        )
         for feature in geometries:
             feature.setdefault("properties", {}).setdefault("style", {}).update(
                 self.style_function(feature)

tests/test_features.py

@@ -17,6 +17,27 @@
 from folium.utilities import JsCode
 
 
+@pytest.mark.parametrize("geometry_type", ["Polygon", "MultiPolygon"])
+def test_topojson_non_collection_geometry(geometry_type):
+    """TopoJson supports objects that are not GeometryCollections."""
+    topology = {
+        "type": "Topology",
+        "objects": {
+            "shape": {
+                "type": geometry_type,
+                "arcs": [[0]] if geometry_type == "Polygon" else [[[0]]],
+            }
+        },
+        "arcs": [[[0, 0], [1, 0], [0, 1], [-1, -1]]],
+        "transform": {"scale": [1, 1], "translate": [0, 0]},
+    }
+
+    map_ = folium.Map()
+    folium.TopoJson(topology, "objects.shape").add_to(map_)
+
+    assert "topojson.feature" in map_.get_root().render()
+
+
 @pytest.fixture
 def tmpl():
     yield ("""