Basically I need to know whether I can use @functools.cached_property in a Flask-RESTPlus Resource subclass to cache an expensive operation or collaborator construction that should not survive beyond a single request.
I'm thinking there are two possibilities:
Resource subclass instance is created fresh for each HTTP request routed to that resource.Resource subclass instance is created once when an API is constructed and reused for every request routed to that resource for the lifetime of the API.Caching on the object/instance would only work in Case 1. @cached_property is in effect a lazyily-computed instance variable, its value computed on first use and stored in an instance variable, then served from that variable on each successive access/call. I expect the mechanism is actually a descriptor, but the concept is the same.
In any case, I need a different value for each request, I just need to use it multiple times in the course of processing a single request and I need the value to be computed exactly once for that request.
Will @cached_property work the way I need on a Flask-RESTPlus Resource subclass?
An instance of the Resource class is created for each request. You can quickly verify by creating a breakpoint in its __init__() method.
Also, consider using the Flask.g namespace object. It has the lifetime of a request context and is typically used to store db connections, etc that need to be created once per request and destroyed after the request ends.