Error On Accessing Global List To Retrieved Stored Value From Realtime Database Firebase

I have a problem on accessing the list. When I am trying to print the length of list global products_url it show an error say that The operation length of list cannot accept the arguments: , [https://. Same error when I am trying to print the length of list product_name.

Use a create empty list block as valueIfTagNotThere

Taifun



Still got this error

because your value is not a list
how do you store the value in Firebase?
Taifun

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I stored it like this. Because if i did not store it like that it will only show the first word (cutted in whitespaces) in the list view.

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I try like this also but still got the same error.