We have already learned a lot about Datastore so far, including how to define entity kinds with model classes, the property concept, and how to make simple queries.
There is a lot more we can do with the NDB Python API to optimize an application, as we will see shortly.
In our Notes application, we defined the CheckListItem model class to represent checkable items, and then we added a property to the Note model named checklist_items that references a list of that kind of entities. This is what we usually call a one-to-many relationship between notes and checklist items, and it is a common way to structure application data. By following this strategy, though, every time we add an item to a note, we have to create and store a new entity on Datastore. This is not a bad practice at all, but we have to take into consideration that we are charged for the use of Datastore depending on the number of operations...