bug: flet_map.Marker/CircleMarker updating behavior

[FeodorFitsner]

Duplicate Check

• I have searched the opened issues and there are no duplicates

Describe the bug

The position of markers on the map does not change after modifying their coordinates followed by updating the map/layer.

The issue is resolved only by replacing the marker with a new instance containing the new coordinates and updating the layer.

Code sample

Code

import flet as ft
from flet_map import (
   Map, InteractionConfiguration, InteractionFlag, MapLatitudeLongitude,
   TileLayer, MarkerLayer, Marker
)
 
     
OPEN_STREET_MAP_URL = 'https://tile.openstreetmap.org/{z}/{x}/{y}.png'


def main(page: ft.Page):
   page.window.width = 400
   page.window.height = 600

   async def handle_tap(e):
       marker = maps.layers[1].markers[0]
       marker.coordinates = e.coordinates
       maps.layers[1].update()

   async def alternative_handler(e):
       marker = Marker(
           content=ft.Icon(ft.Icons.random(), color=ft.Colors.BLACK),
           coordinates=e.coordinates
       )
       maps.layers[1].markers[0] = marker
       maps.layers[1].update()

   maps = Map(
       expand=True,
       initial_center=MapLatitudeLongitude(50.599, 36.598),
       initial_zoom=10,
       interaction_configuration=InteractionConfiguration(
           flags=InteractionFlag.ALL
       ),
       keep_alive=True,
       max_zoom=20,
       min_zoom=2,
       layers=[
           TileLayer(url_template=OPEN_STREET_MAP_URL),
           MarkerLayer([
               Marker(
                   content=ft.Icon(ft.Icons.random(), color=ft.Colors.BLACK),
                   coordinates=MapLatitudeLongitude(50.599, 36.598)
               )
           ])
       ],
       on_tap=handle_tap,
       on_long_press=alternative_handler
   )

   page.add(maps)


if __name__ == '__main__':
   ft.run(main)

To reproduce

Run the code

Expected behavior

I expect the marker's position to change after its coordinates are changed and the layer/map is updated.

Screenshots / Videos

No response

Operating System

macOS

Operating system details

26.2

Flet version

0.80.1

Regression

I'm not sure / I don't know

Suggestions

No response

Logs

No response

Additional details

No response

[tedthebot]

Thanks for the detailed repro — that’s very helpful.

From the description, it sounds like the MarkerLayer diffing doesn’t notice in‑place mutations to an existing Marker, so the layer doesn’t repaint unless the list or marker instance changes. As a workaround, you can reassign the list (or replace the marker), e.g.:

marker = maps.layers[1].markers[0]
marker.coordinates = e.coordinates
maps.layers[1].markers = list(maps.layers[1].markers)
maps.layers[1].update()

Could you share:

• flet_map package version
• flet and Flutter versions (flet doctor output is fine)
• Whether this happens on other platforms (web/Windows/Linux), or only macOS

If the in‑place mutation isn’t detected, that’s likely a bug in flet_map. With the version info, we can confirm and escalate to maintainers.

[FeodorFitsner]

Sure:

• flet_map 0.80.1
• flet 0.80.1
• I haven't tested on other platforms.

[tedthebot]

Thanks for the versions!

A couple quick checks that would help narrow this down:

• When you update the coordinates, does calling marker.update() (or maps.update()) change anything, or is it only the “replace marker instance” workaround that works?
• Does the same behavior happen on another platform (web/Windows/Linux), or only on macOS 26.2?
• Can you confirm if this still reproduces on the latest flet/flet_map (e.g., re-install to be sure you’re on 0.80.1)?

If updating the marker itself doesn’t move it, that’s likely a bug in flet_map’s marker diffing. Your workaround (replace the marker instance and update the layer) is valid for now; once we confirm it’s reproducible, we can escalate to maintainers.

[FeodorFitsner]

I cannot test on other platforms - I have only Mac.
I'm sure flet_map is the latest: 0.80.1
Yes, calling marker.update() fixes the issue.

[tedthebot]

Thanks for confirming — that’s helpful. Since marker.update() fixes it, this looks like a diffing/refresh issue in flet_map where changing Marker.coordinates isn’t being picked up by the layer update. I’ll flag this for maintainers.

For now, the safest workaround is either:

• call marker.update() after changing coordinates, or
• replace the marker instance (as you already did).

Quick checks if you have a moment:

• Does the same happen with CircleMarker?
• Does calling maps.update() or await page.update_async() change anything?
• Can you paste pip show flet flet-map so we can confirm exact versions?

No worries if you can only test on macOS — we can proceed with that.

[FeodorFitsner]

I can't do quick checks. Escalate already.