Hi,
to communicate between bases, you need to use sync. I think, you should create something like field with ‘Modified time’, then formula ‘if {FieldName}=TODAY()’, and make it synced view to some ‘upload’ table in BaseB
In BaseB, should be an automation where each new or changed record in ‘upload’ will be copied to second ‘common’ table of BaseB.
Tricky part is when user updates field that already contains attachment(s).
Record in Base B will contain all available documents in cell, not only new.
HARD WAY
You can write script to check
(example of mine for task which is close to yours, but within the same base): Attachment automation to add and not replace attachment - #3 by Alexey_Gusev
or , if you want to perform it with ‘low code’, you can follow
EASY WAY
assume that new document will appear at the end of list of URLs which you can use to create a new record.
so you can use array method ‘pop’ to read value from the end of array of urls
despite it still contains code, it’s just 2 lines, quite obvious even for non-coders


That way is not 100% accurate for cases, when user adds several documents. To achieve 100% you might think about loop all array and compare each element with urls already existing.
Hi,
to communicate between bases, you need to use sync. I think, you should create something like field with ‘Modified time’, then formula ‘if {FieldName}=TODAY()’, and make it synced view to some ‘upload’ table in BaseB
In BaseB, should be an automation where each new or changed record in ‘upload’ will be copied to second ‘common’ table of BaseB.
Tricky part is when user updates field that already contains attachment(s).
Record in Base B will contain all available documents in cell, not only new.
HARD WAY
You can write script to check
(example of mine for task which is close to yours, but within the same base): Attachment automation to add and not replace attachment - #3 by Alexey_Gusev
or , if you want to perform it with ‘low code’, you can follow
EASY WAY
assume that new document will appear at the end of list of URLs which you can use to create a new record.
so you can use array method ‘pop’ to read value from the end of array of urls
despite it still contains code, it’s just 2 lines, quite obvious even for non-coders


That way is not 100% accurate for cases, when user adds several documents. To achieve 100% you might think about loop all array and compare each element with urls already existing.
Thank you Alexy for your detailed explanation. I will try to implement your solution.