selectedData not populated when graph with selection loads

Inizia eseguendo l’esempio Python fornito con dcc.Graph, un rettangolo Plotly preselezionato e il callback selectedData per riprodurre il valore iniziale mancante. Traccia il percorso dell’evento selectedData utilizzato quando viene caricato il grafico, quindi verifica che il callback riceva la selezione preesistente senza richiedere all’utente di spostarla.

Describe your context
Please provide us your environment, so we can easily reproduce the issue.

• replace the result of pip list | grep dash below

Package              Version                   Location
-------------------- ------------------------- --------------------------------------------------------------------
anyio                3.5.0
appdirs              1.4.4
appnope              0.1.3
argon2-cffi          21.3.0
argon2-cffi-bindings 21.2.0
asttokens            2.0.5
attrs                21.4.0
Babel                2.9.1
backcall             0.2.0
backports.tempfile   1.0
backports.weakref    1.0.post1
beautifulsoup4       4.10.0
black                22.3.0
bleach               4.1.0
Brotli               1.0.9
certifi              2021.10.8
cffi                 1.15.0
cfgv                 3.3.1
charset-normalizer   2.0.12
click                8.1.2
click-plugins        1.1.1
cligj                0.7.2
colorcet             3.0.0
coverage             4.3.1
dash                 2.6.0
dash-core-components 2.0.0
dash-html-components 2.0.0
dash-table           5.0.0
debugpy              1.6.0
decorator            5.1.1
defusedxml           0.7.1
distlib              0.3.4
entrypoints          0.4
executing            0.8.3
fastjsonschema       2.15.3
filelock             3.6.0
Fiona                1.8.21
Flask                2.1.3
Flask-Compress       1.12
geopandas            0.10.2
identify             2.4.12
idna                 3.3
importlib-metadata   4.11.3
inflect              5.4.0
ipykernel            6.12.1
ipython              8.2.0
ipython-genutils     0.2.0
ipywidgets           7.7.0
itsdangerous         2.1.2
jedi                 0.18.1
Jinja2               3.1.1
json5                0.9.6
jsonschema           4.4.0
jupyter              1.0.0
jupyter-client       7.2.1
jupyter-console      6.4.3
jupyter-core         4.9.2
jupyter-server       1.16.0
jupyterlab           3.3.2
jupyterlab-pygments  0.1.2
jupyterlab-server    2.12.0
jupyterlab-widgets   1.1.0
jupytext             1.13.7
markdown-it-py       1.1.0
MarkupSafe           2.1.1
matplotlib-inline    0.1.3
mdit-py-plugins      0.3.0
mistune              0.8.4
mock                 2.0.0
more-itertools       8.12.0
munch                2.5.0
mypy-extensions      0.4.3
nbclassic            0.3.7
nbclient             0.5.13
nbconvert            6.4.5
nbformat             5.3.0
nest-asyncio         1.5.5
nodeenv              1.6.0
notebook             6.4.10
notebook-shim        0.1.0
numpy                1.22.3
packaging            21.3
pandas               1.4.2
pandocfilters        1.5.0
param                1.12.1
parso                0.8.3
pathspec             0.9.0
pbr                  5.8.1
pexpect              4.8.0
pickleshare          0.7.5
Pillow               9.1.0
pip                  21.2.4
platformdirs         2.5.1
plotly               (built from latest Plotly.js)
pluggy               0.6.0
pre-commit           2.18.1
prometheus-client    0.13.1
prompt-toolkit       3.0.28
psutil               5.9.0
ptyprocess           0.7.0
pure-eval            0.2.2
py                   1.11.0
pycparser            2.21
pyct                 0.4.8
Pygments             2.11.2
pyparsing            3.0.7
pyproj               3.3.0
pyrsistent           0.18.1
pyshp                2.2.0
pytest               3.5.1
python-dateutil      2.8.2
pytz                 2022.1
PyYAML               6.0
pyzmq                22.3.0
qtconsole            5.3.0
QtPy                 2.0.1
regex                2022.3.15
requests             2.27.1
scipy                1.8.0
Send2Trash           1.8.0
setuptools           58.0.4
Shapely              1.8.1.post1
six                  1.16.0
sniffio              1.2.0
soupsieve            2.3.1
stack-data           0.2.0
tenacity             8.0.1
terminado            0.13.3
testpath             0.6.0
toml                 0.10.2
tomli                2.0.1
tornado              6.1
traitlets            5.1.1
typed-ast            1.5.2
typing_extensions    4.1.1
urllib3              1.26.9
virtualenv           20.14.0
wcwidth              0.2.5
webencodings         0.5.1
websocket-client     1.3.2
Werkzeug             2.1.2
wheel                0.37.1
widgetsnbextension   3.6.0
xarray               2022.3.0
zipp                 3.7.0

Describe the bug

When creating a graph that has a selection pre-selected, this isn't shown in selectedData when the graph loads. The user needs to move or alter the selection for something to populate in selectedData

Expected behavior

selectedData would show

Screenshots
Graph on load:

After moving the selection:

Example code:

import json

from dash import Dash, dcc, html
from dash.dependencies import Input, Output
import plotly.express as px

external_stylesheets = ['https://codepen.io/chriddyp/pen/bWLwgP.css']

app = Dash(__name__, external_stylesheets=external_stylesheets)

styles = {
    'pre': {
        'border': 'thin lightgrey solid',
        'overflowX': 'scroll'
    }
}

df = px.data.iris()
fig = px.scatter(df, x="sepal_width", y="sepal_length", color='petal_length')

fig.add_selection(type="rect",
    x0=3.0, y0=6.5, x1=3.5, y1=5.5,
    line=dict(
        color="Crimson",
        width=2,
        dash="dash",
    ))

fig.update_layout(dragmode='select',
                  newselection=dict(line=dict(color='blue')))

app.layout = html.Div([
    dcc.Graph(
        id='basic-interactions-3',
        figure=fig
    ),

        html.Div([
            dcc.Markdown("""
                **Selection Data**

            """),
            html.Pre(id='selected-data-3', style=styles['pre']),
        ]),

])


@app.callback(
    Output('selected-data-3', 'children'),
    Input('basic-interactions-3', 'selectedData'))
def display_selected_data(selectedData):
    return json.dumps(selectedData, indent=2)


if __name__ == '__main__':
    app.run_server(debug=True)

@archmoj