plotly dash chained callback - python

This is my code
app = Dash(__name__)
app.layout = html.Div([
dcc.Location(id='url', refresh=False),
dcc.Dropdown(options=['bar', 'pie'], id='dropdown', multi=False, value='bar', placeholder='Select graph type'),
html.Div(id='page-content'),
])
#app.callback(
Output('see1', 'options'),
Input('url', 'search')
)
def ex_projecKey(search):
return re.search('project_key=(.*)', search).group(1)
#app.callback(
Output('page-content', 'children'),
Input('see1', 'options'),
Input('dropdown', 'value')
)
def update_page(options, value):
return f'{options}.{value}'
if __name__ == '__main__':
app.run_server(debug=True, port=4444)
I receive something URL and search project_key
after choice dropdown menu like bar or pie
Then i receive two object (project_key, graph_type )
But two error occur
Property "options" was used with component ID:
"see1"
in one of the Input items of a callback.
This ID is assigned to a dash_html_components.Div component
in the layout, which does not support this property.
This ID was used in the callback(s) for Output(s):
page-content.children
Property "options" was used with component ID:
"see1"
in one of the Output items of a callback.
This ID is assigned to a dash_html_components.Div component
in the layout, which does not support this property.
This ID was used in the callback(s) for Output(s):
see1.options
first callback Output see1, options
Than second callback Input receive that options inst it?

You get an error because you did not define see1 in the layout. I don't know which type of object you want see1 to be, but I think if it is juste to pass data bewteen callback, you should use dcc.Store. So you would call it with Output('see1', 'data') instead of Output('see1', 'options').
Full code :
from dash import dcc, html, Dash, Input, Output
import re
app = Dash(__name__)
app.layout = html.Div([
dcc.Location(id='url', refresh=False),
dcc.Dropdown(options=['bar', 'pie'], id='dropdown', multi=False, value='bar', placeholder='Select graph type'),
html.Div(id='page-content'),
dcc.Store(id="see1", storage_type='memory'), # define see1 in layout as dcc.Store component
])
#app.callback(
Output('see1', 'data'), # use 'data' property
Input('url', 'search')
)
def ex_projecKey(search):
return re.search('project_key=(.*)', search).group(1)
#app.callback(
Output('page-content', 'children'),
Input('see1', 'data'),
Input('dropdown', 'value')
)
def update_page(options, value):
return f'{options}.{value}'
if __name__ == '__main__':
app.run_server(debug=True, port=4444)

Related

How to save input from a dbc.Modal and write to mySql database in Python Dash app?

I have created a button when clicked will pop up a dash boostrap component, dbc.Modal with a couple input fields. Now I'm wondering how can I save this input information and write to a database like MySQL.
I know how to read/write to a DB in the context of a regular html button in Dash with a callback function that triggers when button clicked. But lost on how to use with a modal and callback. I couldn't find any examples online and documentations don't show how to use a modal to save input data and connect with external DB. Please advise. Below is a segment of my code:
Edited Code:
dbc.Modal(
[
dbc.ModalHeader("Add Favorite Faculty"),
dbc.ModalBody(
dbc.Form(
[
dbc.Row(
[
dbc.Label("Enter Name:", id="fav-name"),
dbc.Input(type="text", placeholder="name")
]
),
html.Br(),
dbc.Row(
[
dbc.Label("Enter Email:", id="fav-email"),
dbc.Input(type="email", placeholder="email")
],
),
html.Br(),
dbc.Row(
[
dbc.Label("Enter Comment:", id="fav-comment"),
dbc.Input(type="text", placeholder="comment")
],
),
html.Br(),
dbc.Button("Submit", id='fav-submit', color="primary"),
],
)
),
dbc.ModalFooter(
dbc.Button("Close", color="secondary", id="close-add-faculty", className="ml-auto")
),
],
id="fav-modal",
is_open=False,
And my basic callback function that just opens and closes the modal. Essentially I want to save the input fields when a submit button is clicked and write to a databse.
# prompt modal
#app.callback(
Output("fav-modal", "is_open"),
[
Input("add-faculty-button", "n_clicks"),
Input("close-add-faculty", "n_clicks")
],
[State("fav-modal", "is_open")]
)
def toggle_modal(n1, n2, is_open):
if n1 or n2:
return not is_open
return is_open
# write to DB
#app.callback(
Output("written", "children"),
[
State("fav-name", "value"),
State("fav-email", "value"),
State("fav-comment", "value")
],
[
Input("fav-submit", "n_clicks")
]
)
def write_to_db(n_clicks, name, email, comment):
if n_clicks is not None:
....
An image of what it looks like:
The fact that these inputs are inside a modal doesn't matter in this case. You can still set up callbacks using those component IDs to get the value of each input, and then use that to pass along to your database.
You may want to consider adding a "submit" button or something like that, which would serve as the trigger for your callback, and take these inputs as State. Otherwise, your callback would fire every time the input updates, and you would likely send lots of unwanted values to your database.
Edit:
You need to add IDs to all the dbc.Input components and the submit button in order to hook them up to the callback. Here's an example.
# layout code
dbc.Input(type="text", placeholder="name", id='name-input')
# end of layout
#app.callback(
Output("some-notification-contaienr", "children"),
[
Input("submit-button", "n_clicks"),
],
[
State("name-input", "value"),
State("email-input", "value"),
State("comment-input", "value"),
]
)
def toggle_modal(submit_clicks, name, email, comment):
if not submit_clicks:
raise PreventUpdate
# some code here to send your stuff to the database
# ...
return 'Successfully submitted.'

Persistence problem for dependent dropdowns in Plotly Dash

I have two dependent dropdowns that I want to persist in user session. I noticed that the persistence doesn't work for the second dropdown. It get reset with no possible value.
Here is a code sample :
from dash import Dash, dcc, html
from dash.dependencies import Input, Output
app = Dash(
prevent_initial_callbacks=True,
suppress_callback_exceptions=True,
)
#app.callback(
Output("dd-client-code", "options"),
Input("dd-clients-seg-1", "value")
)
def dd_client_code(client_seg_1):
#any function would do for generate_options
return generate_options(selected_segment=client_seg_1)
dd1 = dcc.Dropdown(
id="dd-clients-seg-1",
options=["record_1", "record_2", "record_3"],
persistence="true",
persistence_type="session",
)
dd2 = dcc.Dropdown(
id="dd-client-code",
persistence="true",
persistence_type="session",
)
app.layout = html.Div(children=[dd1, dd2])
app.run_server(debug=True)
Can anyone help me ?
The persistent values for both dropdowns are stored as expected...
but the value for dd2 is updated to null when the page is reloaded because dd2 has no options at that time.
The callback to update dd2 is not called when the page is reloaded. Even if the callback was called it would be too late because of the first issue.
The following modified code uses dcc.Store to store the value of dd1 each time it is changed. dcc.Interval is used to ensure that the callback is called after the page reload. dd2 is turned into a function that takes the value of dd1 and is called by a new callback that triggers on the interval to update the layout.
import dash.exceptions
from dash import Dash, dcc, html
from dash.dependencies import Input, Output, State
app = Dash(
prevent_initial_callbacks=True,
suppress_callback_exceptions=True,
)
def generate_options(selected_segment):
if selected_segment == "record_1":
return ["A", "B", "C"]
elif selected_segment == "record_2":
return ["One", "Two", "Three"]
else:
return ["Small", "Medium", "Large"]
dd1 = dcc.Dropdown(
id="dd-clients-seg-1",
options=["record_1", "record_2", "record_3"],
persistence="true",
persistence_type="session",
)
def dd2(dd1_value):
"""Return a dd2 dropdown with the appropriate options based on dd1 value"""
options = [] if not dd1_value else generate_options(dd1_value)
return dcc.Dropdown(
id="dd-client-code",
options=options,
persistence="true",
persistence_type="session",
)
#app.callback(
Output("dd-client-code", "options"),
# Store the value of dd1 dropdown when it changes
Output("dd-clients-seg-1-value", "data"),
Input("dd-clients-seg-1", "value")
)
def dd_client_code(client_seg_1):
if not client_seg_1:
raise dash.exceptions.PreventUpdate
return generate_options(client_seg_1), client_seg_1
#app.callback(
Output("dd2-div", "children"),
Input("interval-timer", "n_intervals"),
State("dd-clients-seg-1-value", "data"),
)
def dd2_div_handler(unused, dd1_value):
"""Update the dd2 menu when triggered by dcc.Interval"""
return dd2(dd1_value)
app.layout = html.Div([
# store the latest value of dd-clients-seg-1 dropdown
dcc.Store("dd-clients-seg-1-value", storage_type="session"),
# fires 1ms after page load
dcc.Interval(id="interval-timer", interval=1, max_intervals=1),
# static menu
dd1,
# dynamic menu: don't put dd2 here to avoid persistent value going null
html.Div(id="dd2-div")
])
app.run_server(debug=True)
This was tested with Dash 2.4.1

How to keep the dropdown value after button click in Dash?

I have an application in which I want to update the dropdown values when the user inputs some text into the dropdown. So far, I managed to get the text from an Input text that the user inputs, but not from the dropdown. The dropdown keeps reseting after clicking in any part of the screen or on the button.
import dash
import dash_html_components as html
import dash_core_components as dcc
import dash_bootstrap_components as dbc
from dash.dependencies import Input, Output, State
app = dash.Dash(
external_stylesheets=[
dbc.themes.BOOTSTRAP])
app.layout = html.Div(
[
dcc.Input(id='helper'),
dcc.Dropdown(id="my-dynamic-dropdown", options=[]),
html.Br(),
html.Br(),
html.Br(),
html.Br(),
html.Br(),
html.Br(),
html.Br(),
dbc.Button('Add to Dropdown', id='dropdown_button', n_clicks=0, color="info",
className="mr-1")
],
)
options = []
#app.callback(
Output("my-dynamic-dropdown", "options"),
Input('dropdown_button', 'n_clicks'),
[State('my-dynamic-dropdown', 'options'),
# State('helper', 'value')
State('my-dynamic-dropdown', 'search_value')
]
)
def update_options(n_clicks,existing_options,helper_value):
if helper_value is None:
print("none value")
return options
else:
print("helper value ",helper_value)
options.append({'label': helper_value, 'value': helper_value})
return options
if __name__ == "__main__":
app.run_server(debug=True)
The dropdown allows a user to search through the existing options, but what you're trying to do is not what the dropdown was designed for. You would either need to write a custom component, use some combination of dropdown and input components, or find a different solution to whatever problem you're trying to solve.

Why doesn't my callback in Dash take any output?

After many tries and research, I can't figure out why, but any target for this callback's output will return a key_error.
layout :
...
app = DjangoDash('liste_app', serve_locally=True)
app.layout = ...
...
...
html.Div(className='card-body',
children=[
dcc.Store(id='sorted_storage', data=''),
html.P(children=['filler text'],
id="sorted_liste", style={'overflow': 'scroll',
'height': '100px'})
])
...
callback :
#app.expanded_callback(
[Output('sorted_storage', 'data')],
[Input('insert', 'n_clicks')],
[State('tabs', 'value')]
)
def insertSortButton(n_clicks, value, **context):
if n_clicks is not None:
liste = get_int_liste(context['request'].session.session_key, int(value))
sorted_liste, time = insertSort(liste)
save_algo_result(sorted_liste, time, context['request'].session.session_key, int(value), 'insert')
else:
sorted_liste = 0
return sorted_liste
error :
File "D:\Projets\Python\Exercices\Algorithmique\venv\lib\site-packages\django_plotly_dash\dash_wrapper.py", line 620, in dispatch_with_args
for component_registration in self.callback_map[target_id]['inputs']:
KeyError: 'sorted_storage.data'
I finally found out what I did wrong : If there is only one Outpput, it must not be in a list.
This is my code, returning key_error :
#app.expanded_callback(
[Output('sorted_storage', 'data')],
[Input('insert', 'n_clicks')],
[State('tabs', 'value')]
)
This is correct code working fine :
#app.expanded_callback(
Output('sorted_storage', 'data'),
[Input('insert', 'n_clicks')],
[State('tabs', 'value')]
)
The missleading part is that Inputs and States work the opposite way :
#app.expanded_callback(
[Output('sorted_storage', 'data')],
Input('insert', 'n_clicks'),
[State('tabs', 'value')]
)
#app.expanded_callback(
[Output('sorted_storage', 'data')],
[Input('insert', 'n_clicks')],
State('tabs', 'value')
)
Those 2 blocks of code return the error "'Input' Object is not iterable"/"'State' object is not iterable".
Hope it can help someone someday

Plotly: Dash button with live graph not working

i developed python dash based application for monitoring. as a part of the project i want to display live graph and change the live graph value based on user input. i am stuck in this part. the live graph getting update when i start typing in input box (eg:temp) the graph keep on updating for each letter like t,te,tem,temp. so i created a button to submit the input value. still the graph updating for each letter.
the code for the same:
app = dash.Dash(__name__)
app.layout = html.Div(
[
dcc.Input(id='input-value', value='example', type='text'),
html.Button('Submit', id="submit-button"),
dcc.Graph(id='live-graph', animate=False),
dcc.Interval(
id='graph-update',
interval=1*1000
),
]
)
call back function is like below
#app.callback(Output('live-graph', 'figure'),
[Input('submit-button','n_clicks')],
state=[State(component_id='sentiment_term', component_property='value')],
events=[Event('graph-update', 'interval')])
def update_graph_scatter(n_clicks, input_value):
conn = sqlite3.connect('database.db')
c = conn.cursor()
df = pd.read_sql("SELECT * FROM table WHERE colume LIKE ? ORDER BY unix DESC LIMIT 1000", conn ,params=('%' + input_value+ '%',))
df.sort_values('unix', inplace=True)
df['date'] = pd.to_datetime(df['unix'],unit='ms')
df.set_index('date', inplace=True)
X = df.index
Y = df.column
data = plotly.graph_objs.Scatter(
x=X,
y=Y,
name='Scatter',
mode= 'lines+markers'
)
return {'data': [data],'layout' : go.Layout(xaxis=dict(range= [min(X),max(X)]),
yaxis=dict(range=[min(Y),max(Y)])}
Note: If i removed the interval the button start working.but i want to be live update as well as button
You could use an intermediate component like a div to save the input from the text field and update that div only on button click.
So you would have
app = dash.Dash(__name__)
app.layout = html.Div([
dcc.Input(id='input-value', value='example', type='text'),
html.Div(['example'], id='input-div', style={'display': 'none'}),
html.Button('Submit', id="submit-button"),
dcc.Graph(id='live-graph', animate=False),
dcc.Interval(
id='graph-update',
interval=1*1000
),
])
Now you update the div only on button click:
#app.callback(Output('input-div', 'children'),
[Input('submit-button', 'n_clicks')],
state=[State(component_id='input-value', component_property='value')])
def update_div(n_clicks, input_value):
return input_value
And the Graph always uses the the div content to query your database (either when the interval triggers or the div changes):
#app.callback(Output('live-graph', 'figure'),
[Input('graph-update', 'interval'),
Input('input-div', 'children')])
def update_graph_scatter(n, input_value):
...
Are you sure the updates on each letter are because of the input? Sounds like the interval updates the graph with the not finished input you are typing.
P.S.: I guess you have a name discrepancy between you Input and State id.

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