Dash: How to use the debugger pin?

[olgabot]

Hello! It is very exciting to see that there is a "Debugger PIN" available when you run a Dash app, but how do you access it? We'd like to use the Flask debugger, but how can we see it?

[chriddyp]

Good question. I don't think that the interactive console debugger is available for requests that happen in "the background" (i.e. for AJAX requests).

In this SO question, people are just writing the failed request to the screen: https://stackoverflow.com/questions/26905425. That's not going to be very helpful in our case because it'll just be a big JS stack trace and might not print the python error. The python console will be more helpful.

So right now, the debug=True mode is only really helpful in that it auto-restarts the server.

An alternative to intercept the error might be to run the code with pdb or ipdb like python -m ipdb -c continue app.py (https://stackoverflow.com/a/2438834/4142536). I haven't tested this myself.

[olgabot]

Yes, the Python console would be the most helpful to inspect objects and their types, values, etc. We'll have to try that, thanks!

BTW, in case you want to see how we ended up implementing dash, here's our app! https://github.com/czbiohub/singlecell-dash