Callback() takes from 2 to 4 positional arguments but 5 were given

Dash Python
1

I am trying to make a dashboard using dash and plotly for the first time and I am getting this error
" callback() takes from 2 to 4 positional arguments but 5 were given"

Can someone please help me with this?

A snippet of code where I am getting the error:

@app.callback(
    Output('d-amount', 'value'),
    Output('slider','value'),
    Input('d-amount','value'),
    Input( 'slider', 'value')
)

def update_purchase_amount(input_v, slider_v): 
    ctx = callback_context
    component_triggered = ctx.triggered[0]["prop_id"].split(".")[0]
    if component_triggered == 'slider':
        input_v = slider_v
    else:
        slider_v = input_v

    return input_v, slider_v

​

2

I don’t believe that you can target the same component property with both an Input and an Output in the same callback.

3

As of Dash 1.19.0, it’s possible to target the same component property in both an Input and Output. See more information and examples here: Advanced Callbacks | Dash for Python Documentation | Plotly

The callback looks right to me. Do you have other callback that might have triggered this error message? Or could you provide a complete minimal example that can be run to reproduce the error?

4

Sure, I am posting the complete code below:
Please help me out with this, I have been stuck on this error since yesterday

from jupyter_dash import JupyterDash  # pip install dash==1.19.0 or higher
from dash import callback_context
import dash_core_components as dcc
import dash_html_components as html
from dash.dependencies import Output, Input
import dash_bootstrap_components as dbcv

import pandas as pd
import plotly.express as px
from datetime import date

df = pd.read_json('testing.json')
df = df.rename_axis('date').reset_index()
df = df.iloc[:-2, :]  # drop last two rows
df['number'] = range(1, len(df)+1)  # this will help us connect RangeSlider to DatePicker 
df['colors'] = "turquoise"  # this will help us color the bar graph
print(df.head()[['date','bpi','number','colors']])



app = JupyterDash(__name__, external_stylesheets=[dbc.themes.BOOTSTRAP])

app.layout = dbc.Container([
    dbc.Row([
        dbc.Col([
            html.H1("'If I Were a Rich Man' Bitcoin Calculator", style={'textAlign':'center'})
        ], width={'size': 10})
    ]),
    dbc.Row([
        dbc.Col([
            dbc.Button(id='invested-btn', children="I've invested in Bitcoin",
                       color='light', size='sm', className='mt-2', style={'width': '50%'}),
        ], width={'size': 5, 'offset': 1})
    ]),
    dbc.Row([
        dbc.Col([
            dbc.Button(id='not-invested-btn', children="I've never invested in Bitcoin",
                       color='info', size='sm', className='mt-1', style={'width': '50%'})
        ], width={'size': 5, 'offset': 1})
    ]),
    dbc.Row([
        dbc.Col([
            dbc.Row([
                dbc.Col([
                    dbc.Card([
                        dbc.CardBody([
                            html.H5("Select Amount:"),
                            dbc.Input(id='d-amount', type='number',
                                      step=1000, value=10000),
                            dcc.Slider(id="slider", min=10000, max=1000000,
                                       step=1000, value=10000,
                                       className="mt-3"),
                        ])
                    ])
                ], width=6),
                dbc.Col([
                    dbc.Card([
                        dbc.CardBody([
                            html.H6("Select Buy $ Sell Dates:"),
                            dcc.DatePickerSingle(
                                id='my-date-picker-start',
                                min_date_allowed=date(2017, 1, 1),
                                max_date_allowed=date(2018, 1, 24),
                                initial_visible_month=date(2017, 2, 17),
                                date=date(2017, 2, 17)
                            ),
                            dcc.DatePickerSingle(
                                id='my-date-picker-end',
                                min_date_allowed=date(2017, 1, 1),
                                max_date_allowed=date(2018, 1, 24),
                                initial_visible_month=date(2017, 12, 16),
                                date=date(2017, 12, 16),
                            ),
                            dcc.RangeSlider(id="slider-date", min=1,
                                            max=389,
                                            step=1, value=[48, 350],
                                            allowCross=False,
                                            className="mt-3"),

                        ])
                    ])
                ], width=6),
            ]),

            dbc.Row(
                dbc.Col(html.Hr(style={'border': "3px solid gray"}),width=12)
            ),

            dbc.Row([
                dbc.Col([
                    dbc.Card([
                        dbc.CardBody([
                            html.H5("Buy Price"),
                            html.H2(id="bought", children="", style={'fontWeight':'bold'})
                        ])
                    ])
                ], width=6),
                dbc.Col([
                    dbc.Card([
                        dbc.CardBody([
                            html.H5("Sell Price"),
                            html.H2(id="sold", children="", style={'fontWeight':'bold'})
                        ])
                    ])
                ], width=6)
            ], className="mb-3"),

            dbc.Row([
                dbc.Col([
                    dbc.Card([
                        dbc.CardBody([
                            html.H5("My Profit"),
                            html.H2(id="profit_num", children="", style={'fontWeight':'bold'})
                        ])
                    ])
                ], width=6),
                dbc.Col([
                    dbc.Card([
                        dbc.CardBody([
                            html.H5("Profit %"),
                            html.H2(id="profit_pct", children="", style={'fontWeight':'bold'})
                        ])
                    ])
                ], width=6)
            ], className="mb-3"),
            dbc.Row([
                dbc.Col([
                    dbc.Card([
                        dbc.CardBody([
                            html.H5("Conclusions"),
                            html.H3(id='concluding-remarks', children="I wish I had a time machine",
                                    style={'fontWeight':'bold', 'textAlign':'center'})
                        ])
                    ])
                ], width=12)
            ], className="mb-3")
        ], width=4),

        dbc.Col([
            dbc.Row([
                dbc.Col([
                    dbc.Card([
                        dbc.CardBody([
                            html.P("Bitcoin Price $ and Buy - Sell Price Range by Date"),
                            dcc.Graph(id="bar-chart", config={'displayModeBar': True},
                                      figure=px.bar(df, x='date', y='bpi').
                                      update_layout(margin=dict(l=20, r=20, t=30, b=20))
                                      )
                        ])
                    ])
                ], width=12),
            ])
        ], width=7)
    ],className="mt-3", justify='center')
], fluid=True, style={'backgroundColor':'lightgrey'})




# Select $ Amount ********************************************************
@app.callback(
    Output('d-amount', 'value'),
    Output('slider','value'),
    Input('d-amount','value'),
    Input('slider', 'value')
)

def update_purchase_amount(input_v, slider_v): 
    ctx = callback_context
    component_triggered = ctx.triggered[0]["prop_id"].split(".")[0]
    if component_triggered == 'slider':
        input_v = slider_v
    else:
        slider_v = input_v

    return input_v, slider_v


# Buy and Sell Dates *****************************************************
@app.callback(
    Output('my-date-picker-start','date'),
    Output('my-date-picker-end','date'),
    Output('slider-date','value'),
    Input('my-date-picker-start','date'),
    Input('my-date-picker-end','date'),
    Input('slider-date', 'value'),
)
def update_purchase_amount(start_date, end_date, slider_v):
    ctx = callback_context
    component_triggered = ctx.triggered[0]["prop_id"].split(".")[0]

    if component_triggered == 'slider-date':
        start_date = df[df.number == slider_v[0]]['date'].values[0]
        end_date = df[df.number == slider_v[1]]['date'].values[0]

    elif component_triggered == 'my-date-picker-start' or component_triggered == 'my-date-picker-end':
        num_start = df[df.date==start_date]['number'].values[0]
        num_end = df[df.date==end_date]['number'].values[0]
        slider_v = [num_start, num_end]

    return start_date, end_date, slider_v


# Update Graph ***********************************************************
@app.callback(
    
    Output('bar-chart','figure'),
    Input('my-date-picker-start','date'),
    Input('my-date-picker-end','date'),
)
def update_graph(start_date, end_date):
    dff = df.copy()
    dff.loc[((dff.date>=start_date) & (dff.date<=end_date)), 'colors'] = 'black'
    fig = px.bar(dff, x='date', y='bpi')
    fig.update_traces(marker_color=dff['colors'])
    fig.update_layout(margin=dict(l=20, r=20, t=30, b=20))

    return fig


# Update Prices and Profits **********************************************
@app.callback(
    Output('bought','children'),
    Output('sold','children'),
    Output('profit_num','children'),
    Output('profit_pct', 'children'),
    [Input('my-date-picker-start','date')],
    [Input('my-date-picker-end','date')],
    [Input('slider', 'value')]
)
def prices_profit(start_date, end_date, slider_v):
    buy_price = df[df.date == start_date]['bpi'].values[0]
    buy_price_formatted = f"${buy_price:,.2f}"
    sold_price = df[df.date == end_date]['bpi'].values[0]
    sold_price_formatted = f"${sold_price:,.2f}"

    new_v = slider_v / 1000
    my_profit = (sold_price - buy_price) * new_v
    my_profit = f"${my_profit:,.0f}"

    margin = sold_price - buy_price
    my_pct_profit = (margin / buy_price) * 100
    my_pct_profit = f"{my_pct_profit:,.0f}%"

    return buy_price_formatted, sold_price_formatted, my_profit, my_pct_profit


# Invested buttons *******************************************************
@app.callback(
    Output('concluding-remarks','children'),
    Output('invested-btn', 'color'),
    Output('not-invested-btn', 'color'),
    Input('invested-btn','n_clicks'),
    Input('not-invested-btn','n_clicks'),
    prevent_initial_call=True
)
def update_buttons(n1, n2):
    ctx = callback_context
    component_triggered = ctx.triggered[0]["prop_id"].split(".")[0]

    if component_triggered == 'not-invested-btn':
        message = "I wish I had a time machine"
        invested_color = 'light'
        not_invested_color= 'info'
    elif component_triggered == 'invested-btn':
        message = "I am rich!"
        invested_color = 'info'
        not_invested_color= 'light'

    return message, invested_color, not_invested_color

app.run_server(mode='jupyterlab')
5

Just guessing here since I couldn’t run your code without any data…Try removing the [ ] from the Inputs in the callback so it looks like:

@app.callback(
    Output('bought','children'),
    Output('sold','children'),
    Output('profit_num','children'),
    Output('profit_pct', 'children'),
    Input('my-date-picker-start','date'),
    Input('my-date-picker-end','date'),
    Input('slider', 'value')
)
6

Thank you so much! It worked!

I got one more problem…there are no more errors but the app isn’t working. Like nothing is happening when I press “Run”.
I am running the code in JupyterLab. Could you help me out with that?

And I am attaching the data file (.json format) below:
.json data file