What is the way to do exception handling in a Graph object in plotly dash?

@kristada619 wrote:

I am making a Dash app where I let the user choose a latitude, longitude, radius and location type to display a map. I want to add exception handling to the code - so that if, say, the user enters strings for latitude, then upon clicking the Submit button, it should return a text in the dcc.Graph area saying “Please enter a numeric value for latitude”, instead of the code breaking and throwing an error there. And likewise for the other inputs.

So I have the following lines in my code:

@app.callback(
	[Output('output_text', 'children'),
	Output('output_graph', 'figure')],
	[Input('submit_button', 'n_clicks')],
	state=[State('input_lat', 'value'),
	State('input_lon', 'value'),
	State('input_radius', 'value'),
	State('input_type', 'value'),
	State('input_key', 'value')])
def update_output(n_clicks, lat_, lon_, radius, loc_type, keyword):
	if n_clicks:
		if not isinstance(lat_, float):
			return "Please enter a numeric value for Latitude."
		if not isinstance(lon_, float):
			return "Please enter a numeric value for Longitude."
		if not isinstance(radius, float):
			return "Please enter a numeric value for radius."
		if not isinstance(loc_type, str):
			return "Please enter a string value for Location Type."

        ## rest of the code

But it does not have the desired output. For example, I entered the string “blah” in the input box for longitude, instead of a floating numeric value, and it still throws error instead of returning the text I intended for it to display in case of this error:

image1920×876 62.4 KB

What is the way to do exception handling in Plotly Dash?

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