Invoke virtual method on a null object Moving list from Tinydb to Mysql

Related to this thread i am tryng to move a list from the tinydb to a mysql server so that can be "shared" to other users

but i have this error:

supposed i have a list stored on tinydb i want to write on mysql server the list
and then read!
read function is ok!

i am not able to write data from tinydb to mysql

testmysql.aia (110.2 KB)

see my answer here Share tinydb via Whatsapp - #19 by Taifun

as these threads are related, let's continue the discussion in your other thread...
I will close this one