Handling null data from MySQL Database

i am new to using dash library. i am creating a dashboard where we display amount, quantity and Items(pie chart) of orders of the user based on location and date. i am have trouble handling null data particularly pie chart. please give suggestion

git-hub link for your reference

I find the Pandas package rather useful to handle my SQL queries and data handling before smashing it into a plot.ly chart.

You can do somethinglike data = pandas.sql_query("query-goes-here.....") and use pandas’ build in data processing like pandas.drop_na or overwrite null/nan values as zeroes etc…