Where did Event class go (from a 4 year old example)?

Dash Python
2

Hi,

Event was removed from Dash many versions ago.

To make it work, just remove the two callbacks that are using it and add clear_on_unhover=True in dcc.Graph, as explained in this post (note that this parameter also changed name!).

An updated version (dash v2) would look like:

from dash import Dash, Input, Output, dcc, html

app = Dash(
    __name__, external_stylesheets=["https://codepen.io/chriddyp/pen/bWLwgP.css"]
)

app.layout = html.Div(
    [
        html.Div(
            [
                html.Div(
                    dcc.Graph(
                        id="graph-1",
                        figure={
                            "data": [
                                {
                                    "x": [1, 2, 3],
                                    "y": [4, 1, 5],
                                    "mode": "markers",
                                    "marker": {"size": 12},
                                }
                            ]
                        },
                    ),
                    className="six columns",
                ),
                html.Div(
                    dcc.Graph(
                        id="graph-2",
                        figure={
                            "data": [
                                {
                                    "x": [1, 2, 3],
                                    "y": [2, 5, 10],
                                    "mode": "markers",
                                    "marker": {"size": 12},
                                }
                            ]
                        },
                        clear_on_unhover=True,
                    ),
                    className="six columns",
                ),
            ],
            className="row",
        ),
        html.Div(id="container"),
    ]
)


@app.callback(
    Output("container", "children"),
    [Input("graph-1", "hoverData"), Input("graph-2", "hoverData")],
)
def updateContent(hoverData1, hoverData2):
    print(hoverData1)
    print(hoverData2)
    if hoverData1 is not None:
        return html.Div([html.Div("Graph 1"), html.Pre(hoverData1)])
    if hoverData2 is not None:
        return html.Div([html.Div("Graph 2"), html.Pre(hoverData2)])


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