Multi Output Callback Incorrect Type

Dash Python
1

While working on my own app I ran into an IncorrectTypeException at my multi output callback. Single output worked just fine. Out of curiosity I also ran the example code from Getting Started Part 2, which then threw had the same problem. I have included the example code as I have copied it, since that is something that shouldn’t have stupid errors. I am using 42.0 and running with jupyter notebook.

import dash
import dash_core_components as dcc
import dash_html_components as html
from dash.dependencies import Input, Output

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

app = dash.Dash(__name__, external_stylesheets=external_stylesheets)

app.layout = html.Div([
    dcc.Input(
        id='num',
        type='number',
        value=5
    ),
    html.Table([
        html.Tr([html.Td(['x', html.Sup(2)]), html.Td(id='square')]),
        html.Tr([html.Td(['x', html.Sup(3)]), html.Td(id='cube')]),
        html.Tr([html.Td([2, html.Sup('x')]), html.Td(id='twos')]),
        html.Tr([html.Td([3, html.Sup('x')]), html.Td(id='threes')]),
        html.Tr([html.Td(['x', html.Sup('x')]), html.Td(id='x^x')]),
    ]),
])


@app.callback(
    [Output('square', 'children'),
     Output('cube', 'children'),
     Output('twos', 'children'),
     Output('threes', 'children'),
     Output('x^x', 'children')],
    [Input('num', 'value')])
def callback_a(x):
    return x**2, x**3, 2**x, 3**x, x**x


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

IncorrectTypeException Traceback (most recent call last)
in
30 Output(‘threes’, ‘children’),
31 Output(‘x^x’, ‘children’)],
—> 32 [Input(‘num’, ‘value’)])
33 def callback_a(x):
34 return x2, x3, 2x, 3x, x**x

…appdata\local\programs\python\python37\lib\site-packages\dash\dash.py in callback(self, output, inputs, state)
877 any([isinstance(val, x) for x in valid]) or
878 type(val).name == ‘unicode’
–> 879 )
880
881 def _validate_value(val, index=None):

…appdata\local\programs\python\python37\lib\site-packages\dash\dash.py in _validate_callback(self, output, inputs, state)
667 ‘Same output was used in a’
668 ’ multi output callback!\n Duplicates:\n {}’.format(
–> 669 ‘,\n’.join(
670 k for k, v in
671 ((str(x), output.count(x)) for x in output)

IncorrectTypeException: The output argument [<dash.dependencies.Output object at 0x00000213C48C4E48>, <dash.dependencies.Output object at 0x00000213C49A2DA0>, <dash.dependencies.Output object at 0x00000213C49A2908>, <dash.dependencies.Output object at 0x00000213C49A2F98>, <dash.dependencies.Output object at 0x00000213C49A2668>] is not of type dash.Output.

Any help would be greatly appreciated.

2

Hi, for me your example is working perfectly fine. Are you sure you updated all dependencies with dash and don’t have other callbacks that has the same outputs?