Fix GeoJsonTooltip/GeoJsonPopup on a single Feature or null properties

folium/features.py

@@ -1191,12 +1191,24 @@ def __init__(
             # noqa outside of type checking.
             self.style = style
 
+    def _geojson_features(self) -> list:
+        """Return the parent GeoJson's features, whatever form its data has."""
+        assert isinstance(self._parent, GeoJson)
+        data = self._parent.data
+        if data.get("type") == "FeatureCollection":
+            return data["features"]
+        if "geometry" in data:
+            # A single Feature.
+            return [data]
+        # A bare geometry has no properties.
+        return []
+
     def warn_for_geometry_collections(self) -> None:
         """Checks for GeoJson GeometryCollection features to warn user about incompatibility."""
         assert isinstance(self._parent, GeoJson)
         geom_collections = [
             feature.get("properties") if feature.get("properties") is not None else key
-            for key, feature in enumerate(self._parent.data["features"])
+            for key, feature in enumerate(self._geojson_features())
             if feature["geometry"]
             and feature["geometry"]["type"] == "GeometryCollection"
         ]
@@ -1212,10 +1224,9 @@ def render(self, **kwargs):
         """Renders the HTML representation of the element."""
         figure = self.get_root()
         if isinstance(self._parent, GeoJson):
+            features = self._geojson_features()
             keys = tuple(
-                self._parent.data["features"][0]["properties"].keys()
-                if self._parent.data["features"]
-                else []
+                (features[0].get("properties") or {}).keys() if features else []
             )
             self.warn_for_geometry_collections()
         elif isinstance(self._parent, TopoJson):

tests/test_features.py

@@ -86,6 +86,39 @@ def test_topojson_non_collection_geometry_detail(detail_type):
     assert "name" in map_.get_root().render()
 
 
+@pytest.mark.parametrize("detail_type", [folium.GeoJsonPopup, folium.GeoJsonTooltip])
+@pytest.mark.parametrize(
+    "properties, fields",
+    [({"name": "A"}, ["name"]), (None, [])],
+    ids=["properties", "null-properties"],
+)
+def test_geojson_single_feature_detail(detail_type, properties, fields):
+    """GeoJson popup and tooltip support a single Feature, not only collections."""
+    feature = {
+        "type": "Feature",
+        "geometry": {"type": "Point", "coordinates": [0, 0]},
+        "properties": properties,
+    }
+
+    map_ = folium.Map()
+    geojson = folium.GeoJson(feature).add_to(map_)
+    detail_type(fields=fields).add_to(geojson)
+
+    rendered = map_.get_root().render()
+    assert all(field in rendered for field in fields)
+
+
+@pytest.mark.parametrize("detail_type", [folium.GeoJsonPopup, folium.GeoJsonTooltip])
+def test_geojson_geometry_detail_unknown_field(detail_type):
+    """A bare geometry has no properties, so any field is reported as missing."""
+    map_ = folium.Map()
+    geojson = folium.GeoJson({"type": "Point", "coordinates": [0, 0]}).add_to(map_)
+    detail_type(fields=["name"]).add_to(geojson)
+
+    with pytest.raises(AssertionError, match="The field name is not available"):
+        map_.get_root().render()
+
+
 @pytest.fixture
 def tmpl():
     yield ("""