Values in input not updating

Dash Python
1

I am trying to use the

app.layout[' ... '].value

to return a value.

My code is as follows:

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

app = dash.Dash()

app.config.supress_callback_exceptions = True

app.layout = html.Div([
    dcc.Input(
        id='datasource',
        value=0,
        type="number"
    ),
    html.Div(id='Value_Display'),
])

@app.callback(
    Output('Value_Display', 'children'),
    [Input('datasource', 'value')])
def display_controls(datasource_value):
    print(app.layout['datasource'].value)
    return datasource_value

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

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One can see that the value gets updated correctly becasue one can see that the

return datasource_value

does properly update. However it can be seen that the value that

return datasource_value

and

app.layout['datasource'].value

are different

I am probably either using app.layout[‘datasource’].value wrong or have complelty misunderstood its function.

Any help would be much appreciated, many thanks

2

Your input is the value of the dropdown, why do you want to use

app.layout[' ... '].value

specifically?

You can just

@app.callback(
    Output('Value_Display', 'children'),
    [Input('datasource', 'value')])
def display_controls(datasource_value):
    print(datasource_value)
    return datasource_value
```
1 Like
3

Sorry I should have specified that this is not my code and that in my actual code I am unable to do this. I need to be able to call the value in the way that I have done. (my code here was merely to illustrate my issue.)

4

My actual issue will be solved if I can call on the value in the way I have specified. Unless it is possible to have a callback within a callback.