The operation add items to list cannot accept the arguments: ,

Hello there,

I am trying to create an app to automate my restaurant business, with an application for the waiters to take notes and the order is automatically transferred to a database that is displayed in the kitchen..

I have this code, which consists of selecting the dish from a drop-down menu and the drink from another, when pressing the add button "aceptar", it correctly adds the dishes to the list and it displays well. The problem is when confirm is pressed, that I should save the selected dishes in the database, but I get the following error =
The operation add items to list cannot accept the arguments.

I have looked at the variables that have been created and it correctly saves the values ​​that it should, but when saving in the database something is wrong. Any idea what it could be? Thank you

Export your .aia file and upload it here.

Hello, I am attaching the project in .aia format


Menu_restaurant.aia (83.3 KB)

I notice in your blocks you are never closing screens, just opening them.


Please see the screen handling instructions at

Your app is small enough to instead use hidden Vertical Arrangements instead of Screens, a simpler approach.

I see you are using just TinyDB, but your app description says you are using the database to communicate across the restaurant. Will you be throwing the phone back and forth?

Regarding the immediate error, I recommend using the Do It facility to examine the value that is returned for your main TinyDB tags. I suspect one of the tags got stuck with a non-list value in your experimentation.

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