Demo of possible bug with Dash Upload component

uploader-not-reset.py

# this has a problem that the "new_jobs" values aren't reset after
# being used.
import dash
import dash_core_components as dcc
import dash_html_components as html
from dash.dependencies import Input, Output, State
from dash.exceptions import PreventUpdate
from flask import Flask, send_file

server = Flask(__name__)
app = dash.Dash(server=server)


app.layout = html.Div(
    children=[
        dcc.Store(id="jobs", storage_type="memory"),
        html.H1("Jobs"),
        html.Div(id="jobs-list"),
        html.H2("Upload your files"),
        dcc.Upload(
            id="upload-data",
            children=html.Div(
                ["Drag and drop or click to select a file to upload."]
            ),
            style={
                # "width": "100%",
                "height": "60px",
                "lineHeight": "60px",
                "borderWidth": "1px",
                "borderStyle": "dashed",
                "borderRadius": "5px",
                "textAlign": "center",
                "margin": "10px",
            },
            multiple=True,
        ),
        html.H2("Delete jobs"),
        dcc.Dropdown(id="jobs-to-delete", multi=True),
        html.Button("Delete Me!", id="delete-jobs-button", n_clicks=0),
    ],
    style={"max-width": "500px"},
)


@app.callback(
    Output("jobs-list", "children"), [Input("jobs", "data")],
)
def display_jobs(jobs):
    return [html.Div(f"Job: {j}") for j in jobs]


@app.callback(
    Output("jobs", "data"),
    [
        Input("upload-data", "filename"),
        Input("delete-jobs-button", "n_clicks"),
    ],
    [State("jobs-to-delete", "value"), State("jobs", "data")],
)
def update_jobs(new_jobs, button, delible_jobs, jobs):
    ctx = dash.callback_context
    print("---")
    print(f"ctx.triggered: {ctx.triggered}")
    print(f"Delible: {delible_jobs}")
    print(f"New: {new_jobs}")
    print(f"Jobs: {jobs}")

    if new_jobs is None and delible_jobs is None:
        raise PreventUpdate

    jobs = jobs or []
    if delible_jobs is not None:
        jobs = [j for j in jobs if j not in delible_jobs]

    if new_jobs is not None:
        jobs += new_jobs
    return jobs


@app.callback(Output("jobs-to-delete", "options"), [Input("jobs", "data")])
def update_deletable_jobs(jobs):
    if jobs is None:
        raise PreventUpdate
    options = [{"label": f"Job: {j}", "value": j} for j in jobs]
    return options


if __name__ == "__main__":
    app.run_server(debug=True, port=8888, host="172.16.193.97")