How to run python script on clicking button?

Question

Goal: I have never done this before, and am new to python. I want to run a python script on call as a button is pushed.

Question: Can someone give pointers as to how to go about solving this?

My Code:

**Button HTML**
    # Layout of Dash App HTML
    app.layout = html.Div(
        children=[
            html.Div(
                            html.Button('Detect', id='button'),
                            html.Div(id='output-container-button',
                            children='Hit the button to update.')
                         ],
                    ),
                ],
            )

@app.callback(
    dash.dependencies.Output('output-container-button', 'children'),
    [dash.dependencies.Input('button')])
def run_script_onClick():
    return os.system('python /Users/ME/Desktop/DSP_Frontend/Pipeline/Pipeline_Dynamic.py')

Currently this gives the error:

Traceback (most recent call last):
  File "app.py", line 592, in <module>
    [dash.dependencies.Input('button')])
TypeError: __init__() missing 1 required positional argument: 'component_property'

EDIT:

I think the solution might be to add some_argument to the run_script_onClick:

def run_script_onClick(some_argument):
        return os.system('python /Users/ME/Desktop/DSP_Frontend/Pipeline/Pipeline_Dynamic.py')

I am currently browsing through this list to find an appropriate item() to use as argument.

What do you understand from that error message? Have you tried fixing that first? — AMC
– AMC, Commented Jan 18, 2020 at 15:41
HI @AMC, it mentions that I am missing another argument for the function I am trying to call. (So something like function(arg1, arg2). Currently it considers 'button' but perhaps another argument that is correlated to the return (the script that should run) ? But I don't know how to go about that exactly. Is my understanding correct? — MSD
– MSD, Commented Jan 18, 2020 at 15:43
Currently it considers 'button' but perhaps another argument that is correlated to the return (the script that should run) ? I'm not sure I understand what you mean. This might be of use: dash.plot.ly/dash-core-components/input. — AMC
– AMC, Commented Jan 18, 2020 at 15:48
@AMC yes I used that link to get where I am now. But I am a bit stuck and am wondering what argument I am missing to make the return python script run upon click. — MSD
– MSD, Commented Jan 18, 2020 at 15:51
While that is a good improvement to make, it's unlikely to fix the current error. Have you seen this page, by the way? — AMC
– AMC, Commented Jan 18, 2020 at 16:12

Yaakov Bressler · Accepted Answer · 2020-01-19 07:38:46Z

5

Here's what I would use:

from subprocess import call
from dash.exceptions import PreventUpdate

@app.callback(
    dash.dependencies.Output('output-container-button', 'children'),
    [dash.dependencies.Input('button', 'n_clicks')])
def run_script_onClick(n_clicks):
    # Don't run unless the button has been pressed...
    if not n_clicks:
        raise PreventUpdate

    script_path = 'python /Users/ME/Desktop/DSP_Frontend/Pipeline/Pipeline_Dynamic.py'
    # The output of a script is always done through a file dump.
    # Let's just say this call dumps some data into an `output_file`
    call(["python3", script_path])

    # Load your output file with "some code"
    output_content = some_loading_function('output file')

    # Now return.
    return output_content

edited Jan 19, 2020 at 7:38

answered Jan 19, 2020 at 6:52

Yaakov Bressler

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4 Comments

MSD Over a year ago

Thanks. I tried what you said. It outputs the following message: ' TypeError: __init__() missing 1 required positional argument: 'component_property' Here are the available properties in "button": ['children', 'id', 'n_clicks', 'n_clicks_timestamp', 'key', 'role', 'data-', 'aria-', 'autoFocus', 'disabled', 'form', 'formAction', 'formEncType', 'formMethod', 'formNoValidate', 'formTarget', 'name', 'type', 'value', 'accessKey', 'className', 'contentEditable', 'contextMenu', 'dir', 'draggable', 'hidden', 'lang', 'spellCheck', 'style', 'tabIndex', 'title', 'loading_state']'

MSD Over a year ago

aah now I get n_clicks better. This clears up a lot. Thanks for that. I'll look more into the 'some_loading_function' part, in order to grasp it better for my case. That file I am trying to run checks whether there has been any new data from sensors. If so, it appends the new data to the existing csv. That is was 'pipeline_dynamic.py' does. So many there is no need for ' output_content = some_loading_function('output file.csv')' as long as the file runs in the background.

MSD Over a year ago

Is there a way to check if the file ran successfully. Now I have commented output_content and return output_content. I have added: print('file loaded successfully). But is there a function that actually check if that file ran successfully or not?

Yaakov Bressler Over a year ago

2 options for you @user7186746 – 1) place a print statement at the end of your pipeline_dynamic.py file or 2) manually inspect the outcome file

Abimbola Ojikutu · Accepted Answer · 2020-09-16 10:34:42Z

1

@ Yaakov Bressler. This works for me without using the following lines. Thanks a lot.

output_content = some_loading_function('output file')
    return output_content

answered Sep 16, 2020 at 10:34

Abimbola Ojikutu

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