Dash beginner questions

Dash Python
1

Hello,

I have a number of relatively small questions. I was hoping some members of the community can help me get started. As a front note I have been working with Python for the last few years, mainly pandas but have learnt plotly basics and have been working on my own trading analytics dashboard for the last few months.

  1. I got attracted by the new addition to dash of running own js/css files that are stored in assets folder. I read the guide to this however as someone with extremely limited knowledge of either in particular I have struggled to understand how to connect these files to the dashboard.

Just to give 2 examples, -

  • I used a simple background color css file to hack color in the gaps between the Divs. That was very straightforward

  • Application of something like particle.js to the dashboard to some pages/on startup.
    Any recommendations on how to begin doing something like that?

  • In fact if you would be able to give some good examples of solutions for special effects/aesthetics for dash, would highly appreciate it.

  1. i have encountered a strange bug on my Dash, whereby I added a parent callback (was trying to add a dcc.loading component), tested it, realised it was not doing what I wanted (I wanted a loading comp. to appear on first start of dash, but it kept appearing every refresh) and deleted it. I deleted it from all files so ctrl-f does not bring it up on any pages, or the app.py file.

Nevertheless it somehow has it in the memory that it was there so on every refresh i’m getting this error:
"KeyError: “Callback function not found for output ‘live-nbp_graph.figure’, perhaps you forgot to prepend the ‘@’?”
(I have already even renamed this component,
restarted python,
restarted machine,
copied code to new files,
renamed file and the app.py runner file).

Please help!

  1. to follow on from (2) I registered today on forum and saw that last year a separate loading components library was made to be used instead of dcc.loading ones.
    I just wanted some clarity on:
    How would you go about implementing one of those or ANY loading component to charts so it runs once only on first load, and after that does not interfere with live updating?

  2. Possibly more of a plotly question, i currently I use ‘figure’ callbacks to return charts, such as
    @callback(Output(‘live-eua_graph_t’,‘figure’).
    this means chart is blank for a while (while fetching data) and then appears all at once.
    Could you recommend how the effect of ‘chart being drawn’ is achieved in dash? example will be great

  3. As the dashboard is still deep in dev stage, I have been running it/trialing it by hosting it on my own machine. I have a small team of users that have been accessing it to see progress and make suggestions and also trialing performance.
    I read in multiple places that running dashboards like that (off personal machine) is not recommended and performance will start to wane quickly.
    Is there a particular ‘quantitative metric’ that some of you have encountered (eg, 20 concurrent users, 10 pages in multi-app, etc.

I just wanted to gauge how soon I will need to explore server hosting options in my company.

Thank you in advance for your responses.
It is my first post and I promise to split out questions in the future.
Just to be clear I have spent at least an hour or more looking for solutions to each of these before posting this.

Thanks,
AS