Building App to Lookup Data From App Local Database, Just like Excel VLOOKUP

MIT App Inventor Help
1

I have a list of chemicals and their corresponding storage locations and they are a lot of chemicals in the list.
I want when a user opens the app, he should have an option to select a chemical name from the list and when a chemical is selected its storage location appears on a label in the app. This way user can go to the location to retrieve the chemical.
The app should be capable of adding new chemicals and their location in app database (local app database). And if a location of any chemical changes their should be an option to update the location of the chemical too.

How should I approach to build this app?

2

Here is a quick and lazy way to do this in TinyDB:

Store your chemicals, locations, and quantities as follows:
tag=JOIN(chemicalName,'@',locationName)
value=quantity of chemicalname at location locationName

Use the new filter list block on a TinyDB.TagList to filter for tags containing
JOIN(chemicalName,'@') to get tags containing chemicalName.
Loop over that tag list to extract quantities and locations for formatting in a ListView.

3

Is there any easy and lazy way to insert a list of chemicals in TinyDB at once instead of doing it one by one?

4

That would be as a three column table (chemicalName,locationName,quantity) under a fixed tag ChemicalLocationQuantities.

Unfortunately, that would make the updating harder later on, because you would have to loop to look up row numbers of subsets of that table.

A for each loop block at table load time is the price for making updates faster.

5

Here is a sample app for you to build on ...

(It has not been updated with the new nb191 filter blocks.)