From 1c6e0926980eae423cbfda1e25618a012b8342b1 Mon Sep 17 00:00:00 2001
From: adarshsm <24850536+adarshsm@users.noreply.github.com>
Date: Sun, 18 Oct 2026 19:28:38 +0530
Subject: [PATCH] Add a popup argument to TopoJson

TopoJson takes a tooltip but no popup, so per-feature popups need a
separate GeoJsonPopup(...).add_to(topojson) call. Accept popup the same
way tooltip is accepted: a GeoJsonPopup or Popup is added as a child and
a string is wrapped in a Popup.

Closes #1461

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
---
 folium/features.py     |  8 ++++++++
 tests/test_features.py | 27 +++++++++++++++++++++++++++
 2 files changed, 35 insertions(+)

diff --git a/folium/features.py b/folium/features.py
index 587f5e053b..829cb44d28 100644
--- a/folium/features.py
+++ b/folium/features.py
@@ -972,6 +972,9 @@ class TopoJson(JSCSSMixin, Layer):
     tooltip: GeoJsonTooltip, Tooltip or str, default None
         Display a text when hovering over the object. Can utilize the data,
         see folium.GeoJsonTooltip for info on how to do that.
+    popup: GeoJsonPopup, Popup or str, default None
+        Show a popup when clicking on the object. Pass a GeoJsonPopup to show
+        a different popup for each feature.
 
     Examples
     --------
@@ -1032,6 +1035,7 @@ def __init__(
         show: bool = True,
         smooth_factor: Optional[float] = None,
         tooltip: Union[str, Tooltip, None] = None,
+        popup: Union[str, Popup, None] = None,
     ):
         super().__init__(name=name, overlay=overlay, control=control, show=show)
         self._name = "TopoJson"
@@ -1059,6 +1063,10 @@ def __init__(
             self.add_child(tooltip)
         elif tooltip is not None:
             self.add_child(Tooltip(tooltip))
+        if isinstance(popup, (GeoJsonPopup, Popup)):
+            self.add_child(popup)
+        elif popup is not None:
+            self.add_child(Popup(popup))
 
     def style_data(self) -> None:
         """Applies self.style_function to each feature of self.data."""
diff --git a/tests/test_features.py b/tests/test_features.py
index e41e0e8337..2cf793cc6e 100644
--- a/tests/test_features.py
+++ b/tests/test_features.py
@@ -86,6 +86,33 @@ def test_topojson_non_collection_geometry_detail(detail_type):
     assert "name" in map_.get_root().render()
 
 
+@pytest.mark.parametrize(
+    "popup", [folium.GeoJsonPopup(fields=["name"]), Popup("hello"), "hello"]
+)
+def test_topojson_popup(popup):
+    """TopoJson accepts a popup, like GeoJson does."""
+    topology = {
+        "type": "Topology",
+        "objects": {
+            "shape": {
+                "type": "Polygon",
+                "arcs": [[0]],
+                "properties": {"name": "A"},
+            }
+        },
+        "arcs": [[[0, 0], [1, 0], [0, 1], [-1, -1]]],
+        "transform": {"scale": [1, 1], "translate": [0, 0]},
+    }
+
+    map_ = folium.Map()
+    topojson = folium.TopoJson(topology, "objects.shape", popup=popup).add_to(map_)
+
+    children = list(topojson._children.values())
+    assert len(children) == 1
+    assert isinstance(children[0], (folium.GeoJsonPopup, Popup))
+    assert f"{topojson.get_name()}.bindPopup(" in map_.get_root().render()
+
+
 @pytest.fixture
 def tmpl():
     yield ("""