Error Class builtinsdict is not mapped, what's the problem?

Question

Flask

Understanding how SQLalchemy Flask works. I want to enter the sparse data into the database (the exchange rate of the Australian dollar type is 1.4465) and display it. But it gives an error "Class 'builtins.str' is not mapped" as I understand it, a problem with the table configuration? I tried to display simple data, only the format changes after "builtins"
https://pastebin.com/1xLCMYJ7

Answer 1

• On Toaster, the source code is recommended to be added to the question as text;
  So yes, we can say that the problem is in the "table configuration", since nothing similar to the exchange rate is described at all. SQLAlchemy does not understand what kind of tuples, where and how to save.
  In general, you are in the SQLAlchemy documentation .