Clientside Callback Cannot read properties of undefined

Dash Python
1

I want to use a clientside callback to create a bbox for a tooltip programmatically. This will hopefully allow me to add the tooltip to a graph at a corresponding vertex when I click on a dash table.

My question is why does a test clientside callback that returns null to a dummy variable throws the error

Cannot read properties of undefined (reading ‘data’)

(This error originated from the built-in JavaScript code that runs Dash apps. Click to see the full stack trace or open your browser’s console.)
TypeError: Cannot read properties of undefined (reading ‘data’)

at _callee2$ (http://127.0.0.1:8050/_dash-component-suites/dash/dash-renderer/build/dash_renderer.v2_7_0m1670590103.dev.js:573:58)

at tryCatch (http://127.0.0.1:8050/_dash-component-suites/dash/dash-renderer/build/dash_renderer.v2_7_0m1670590103.dev.js:409:2404)

at Generator._invoke (http://127.0.0.1:8050/_dash-component-suites/dash/dash-renderer/build/dash_renderer.v2_7_0m1670590103.dev.js:409:1964)

at Generator.next (http://127.0.0.1:8050/_dash-component-suites/dash/dash-renderer/build/dash_renderer.v2_7_0m1670590103.dev.js:409:3255)

at asyncGeneratorStep (http://127.0.0.1:8050/_dash-component-suites/dash/dash-renderer/build/dash_renderer.v2_7_0m1670590103.dev.js:413:103)

at _next (http://127.0.0.1:8050/_dash-component-suites/dash/dash-renderer/build/dash_renderer.v2_7_0m1670590103.dev.js:414:194)

at http://127.0.0.1:8050/_dash-component-suites/dash/dash-renderer/build/dash_renderer.v2_7_0m1670590103.dev.js:414:364

at new Promise (<anonymous>)

at http://127.0.0.1:8050/_dash-component-suites/dash/dash-renderer/build/dash_renderer.v2_7_0m1670590103.dev.js:414:97

at handleClientside (http://127.0.0.1:8050/_dash-component-suites/dash/dash-renderer/build/dash_renderer.v2_7_0m1670590103.dev.js:525:28)

Sample code is below.

from jupyter_dash import JupyterDash
from dash import Dash, dcc, html, no_update, dash_table, callback_context, State, Input, Output
from dash.exceptions import PreventUpdate
import plotly.express as px
import pandas as pd

dict_list = [{‘fid’:1, ‘field1’:‘test1’, ‘x’:1, ‘y’:1}, {‘fid’:2, ‘field1’:‘test2’, ‘x’:2, ‘y’:2}, {‘fid’:3, ‘field1’:‘test3’, ‘x’:3, ‘y’:1}]
df = pd.DataFrame(dict_list)
fig = px.line(df, x=‘x’, y=‘y’, hover_data=[df.fid])
fig.update_traces(
hoverinfo=“none”,
hovertemplate=None,
marker=dict(size=30)
)

app = JupyterDash(name)

app.layout = html.Div(className=“container”,
children=[dcc.Store(id=“get_tooltip”), dcc.Store(id=“get_tooltip2”),dash_table.DataTable(id=‘flight_table’, data = dict_list,
columns=[{“name”: i, “id”: i} for i in [‘fid’, ‘field1’]],
page_current=0,
page_size=20,
page_action=‘custom’,
filter_action=‘custom’,
filter_query=‘’,
sort_action=‘custom’,
sort_mode=‘multi’,
sort_by=,
style_filter_conditional=[{
‘if’: {‘column_id’: ‘date_processed’},
‘pointer-events’: ‘None’}]),

    dcc.Graph(
        id="asp_graph",
        figure=fig,
        clear_on_unhover=True),
    dcc.Tooltip(
        id="graph-tooltip",
        background_color="lightgrey",
        border_color="blue"),
],

)

@app.callback(
Output(“get_tooltip”, “data”),
Output(“flight_table”, “active_cell”),
Input(“asp_graph”, “clickData”),
Input(“asp_graph”, “figure”),
Input(“flight_table”, “active_cell”),
Input(“flight_table”, “data”),
State(“flight_table”, “page_size”)
)
def main_func(clickData, dict_fig, active_cell, flight_table, page_size):
triggered_id = callback_context.triggered[0][‘prop_id’]

if 'asp_graph.clickData' == triggered_id:
    fid = clickData['points'][0]['customdata'][0]
    try:
        idx = df.index[df['fid'] == fid][0]
        activecell, selectedcells = [None, []]
    except:
        idx = 0
        activecell, selectedcells = [None, []]
    return fid, active_cell
elif 'flight_table.active_cell' == triggered_id:
    fid = flight_table[active_cell['row']]['fid']
    return fid, active_cell
else:
    raise PreventUpdate

app.clientside_callback(
“”"
function(fid) {
return null
}
“”",
Output(“get_tooltip2”, “data”),
Input(“get_tooltip”, “data”),
)

2

Hi @jgm ,

could you please format your code so that we can copy&paste it?

3

Where do you use this variables?

4

Hello @jgm,

I think this may be because on initial load, your dcc store doesn’t have anything.

Try giving it an empty list.

5

I haven’t implemented a use for ActitveCell and selectedCellss yet in this test script. In my working code I use Active cell to add a hyperlink to the table and to get data to link to a graph and map.

6

Giving it an empty list didn’t work. The code above mysteriously started working, then after making changes, it stopped.

1 Like
7

What version of dash are you running?

8

Hi there,

I don’t know what this app actually does, but the callback structure works as far as I can tell. I don’t get any error message. Maybe I am missing something. Try this:

from dash import Dash, dcc, html, dash_table, callback_context, State, Input, Output
from dash.exceptions import PreventUpdate
import plotly.express as px
import pandas as pd

dict_list = [
    {
        'fid': 1,
        'field1': 'test1',
        'x': 1,
        'y': 1
    },
    {
        'fid': 2,
        'field1': 'test2'
        , 'x': 2,
        'y': 2
    },
    {
        'fid': 3,
        'field1': 'test3',
        'x': 3,
        'y': 1
    }
]
df = pd.DataFrame(dict_list)
fig = px.scatter(df, x='x', y='y', hover_data=[df.fid])
fig.update_traces(
    hoverinfo="none",
    hovertemplate=None,
    marker=dict(size=30)
)

app = Dash(__name__)

app.layout = html.Div(
    className="container",
    children=[
        dcc.Store(id="get_tooltip"),
        dcc.Store(id="get_tooltip2"),
        dash_table.DataTable(
            id='flight_table',
            data=dict_list,
            columns=[{"name": i, "id": i} for i in ['fid', 'field1']],
            page_current=0,
            page_size=20,
            page_action='custom',
            filter_action='custom',
            filter_query='',
            sort_action='custom',
            sort_mode='multi',
            # sort_by=,
            style_filter_conditional=[
                {
                    'if': {'column_id': 'date_processed'},
                    'pointer-events': 'None'
                }
            ]
        ),

        dcc.Graph(
            id="asp_graph",
            figure=fig,
            clear_on_unhover=True
        ),
        dcc.Tooltip(
            id="graph-tooltip",
            background_color="lightgrey",
            border_color="blue"
        ),
        html.Div(id='dummy'),
        html.Div(id='dummy2')
    ],

)


@app.callback(
    Output("dummy2", "children"),
    Output("get_tooltip", "data"),
    # Output("flight_table", "active_cell"),
    Input("asp_graph", "clickData"),
    Input("asp_graph", "figure"),
    Input("flight_table", "active_cell"),
    Input("flight_table", "data"),
    State("flight_table", "page_size")
)
def main_func(clickData, dict_fig, active_cell, flight_table, page_size):
    triggered_id = callback_context.triggered[0]['prop_id']

    if 'asp_graph.clickData' == triggered_id:
        fid = clickData['points'][0]['customdata'][0]
        try:
            idx = df.index[df['fid'] == fid][0]
            activecell, selectedcells = [None, []]
        except:
            idx = 0
            activecell, selectedcells = [None, []]
        return fid, active_cell
    elif 'flight_table.active_cell' == triggered_id:
        fid = flight_table[active_cell['row']]['fid']
        return fid, active_cell
    else:
        raise PreventUpdate


app.clientside_callback(
    """
    function(fid) {
        return ['output from clientside callback: random number', Math.random()]
    }
    """,
    Output("dummy", "children"),
    # Output("get_tooltip2", "data"),
    Input("get_tooltip", "data"),
    prevent_initial_call=True
)

if __name__ == '__main__':
    app.run(debug=True)
9

It works for me if I put the clientside callback in the assets folder as a .js.

I’m using jupyter-dash 0.4.2 and dash 2.7.0

10

That error happens frequently when using debug mode for me.