Reactivity lost when UI items are inside list/dict

[imagejan]

Describe the bug

I'd like to dynamically change the number of input widgets (here: radio button groups) by putting them inside a list or dict.

While the display of radio button groups in a mo.hstack works fine and adjusts to the user-defined number, updating the selected radio-button values doesn't trigger re-running of the subsequent cells.

I guess that's explainable because the list/dict objects themselves don't change, but is there a simple way to restore reactivity for the case of UI elements nested in lists?

Environment

{
  "marimo": "0.11.4",
  "OS": "Windows",
  "OS Version": "10",
  "Processor": "Intel64 Family 6 Model 165 Stepping 2, GenuineIntel",
  "Python Version": "3.12.7",
  "Binaries": {
    "Browser": "133.0.6943.60",
    "Node": "--"
  },
  "Dependencies": {
    "click": "8.1.7",
    "docutils": "0.21.2",
    "itsdangerous": "2.2.0",
    "jedi": "0.19.1",
    "markdown": "3.7",
    "narwhals": "1.22.0",
    "packaging": "24.1",
    "psutil": "6.1.0",
    "pygments": "2.18.0",
    "pymdown-extensions": "10.14.3",
    "pyyaml": "6.0.2",
    "ruff": "0.9.6",
    "starlette": "0.45.3",
    "tomlkit": "0.13.2",
    "typing-extensions": "4.12.2",
    "uvicorn": "0.34.0",
    "websockets": "14.2"
  },
  "Optional Dependencies": {
    "altair": "5.5.0",
    "pandas": "2.2.3",
    "pyarrow": "19.0.0"
  },
  "Experimental Flags": {}
}

Code to reproduce

Here's a minimal example:

import marimo

__generated_with = "0.11.4"
app = marimo.App(width="medium")


@app.cell
def _():
    import marimo as mo
    return (mo,)


@app.cell
def _(mo):
    num_categories = mo.ui.slider(start=1, stop=5)
    num_categories
    return (num_categories,)


@app.cell
def _(mo, num_categories):
    selections = {}
    for _c in range(num_categories.value):
        selections[_c] = mo.ui.radio(["1", "2", "3"])
    return (selections,)


@app.cell
def _(mo, selections):
    mo.hstack([_select for _, _select in selections.items()], justify="start")
    return


@app.cell
def _(selections):
    [_s.value for _, _s in selections.items()]
    return


@app.cell
def _(mo, num_categories):
    selections_list = []
    for _ in range(num_categories.value):
        selections_list.append(mo.ui.radio(["1", "2", "3"]))
    return (selections_list,)


@app.cell
def _(mo, selections_list):
    mo.hstack(selections_list, justify="start")
    return


@app.cell
def _(selections_list):
    [_s.value for _s in selections_list]
    return


@app.cell
def _():
    return


if __name__ == "__main__":
    app.run()

Try selecting some of the radio buttons and observe that the subsequent cells don't update.

[imagejan]

Sorry, I should have read the documentation in more detail.

The intended way to solve this is by using mo.ui.array().

Closing this, sorry for the buzz.