Missing Global Variables?

MIT App Inventor Help
1

Hello...

I am trying to create an app for people to log their blood pressure. I currently have 3 screens

  • A Profile screen that asks for name, age, weight, ethnicity, height
  • A View screen - where, once the profile has filled in, people add a datestamped 120/80 like reading

I also have an Admin screen to clear the readings etc... bits and bobs.

I am using TinyDB and have 4 instances ProfileDB, diaryDB, medicationsDB and informationDB
I am currently using a ListView to show the readings but later it could also be a chart.
I store/use the readingsDB in a "readings" global.

My problem is this.. I am trying to store the readings (essentially a list of lists) and to begin with I did this... to set up my data.

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image2330×1436 438 KB

All was working fine... I could add items to the list, but when moving things around a bit ... all of a sudden on the viewEntries screen, the variables objects no longer know about my "readings" variable

You can see lots of red crosses on my code.

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image1460×1164 119 KB

The problem started after I'd temporarily added the initialise variable code to a function block.... then moved it out again...

Can anyone spot anything awry?

Thanks

Tom

2

Global variables are only accessible within the screen that holds their init global block.

3

Ah thanks... and are they init'd if they already exist... Or do you just add the block to say you want to use it?

4

Add the variable block on each screen that requires it, and load the data for that variable from the tinydb

1 Like
5

Many people avoid the problem by using stacked Vertical Arrangements instead of screens.
Keep them invisible, only one visible at a time.

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