Improve compatibility with web.View and support subclassing PydanticViews

[drderuiter]

The changes in this PR make PydanticView structurally a subclass of the aiohttp.web.View. It should make it easier to use PydanticView in places where a regular View is expected. The changes also allow one to inherit from a PydanticView.

Rationale

I was working with aiohttp_pydantic in combination with some other tool, which are designed to work with a regular View. The tool assumed that for non-allowed methods, the handler attribute was missing. This is not the case for the current PydanticView, which sets the raise_not_allowed handler for such methods.

The tool would also subclass the View, which does not work for an PydanticView. Upon subclassing:

• all methods on the child view become "allowed methods", as the parent view gets a handler method even for the non-allwed methods;
• inherited, allowed methods are decorated again.

Implementation

• Align the way unsupported methods are handles with aiohttp.web.View. This solves part of the inheritance problem, as no methods are attached for non-allowed methods.
• When subclassing, only decorate allowed methods that were not inherited from a PydanticView base class.

Alternative solutions

For the inheritance problem, another solution could be to just raise a warning when a subclass of PydanticView is subclassed again. That does not solve the problem, but will let users know that this was not the intended usage.

Curious to hear your thoughts. I'm aware that this is a breaking change as it changes the public interface, but the added compatibility with regular the View should be useful.

[codecov-commenter]

Codecov Report

Merging #15 (c92437c) into main (324c9b0) will decrease coverage by 0.09%. The diff coverage is 93.33%.

@@            Coverage Diff             @@
##             main      #15      +/-   ##
==========================================
- Coverage   92.82%   92.73%   -0.10%     
==========================================
  Files          11       11              
  Lines         683      688       +5     
==========================================
+ Hits          634      638       +4     
- Misses         49       50       +1     

Impacted Files	Coverage Δ
aiohttp_pydantic/view.py	97.14% <93.33%> (-1.32%)	:arrow_down:

---

Continue to review full report at Codecov.

Legend - Click here to learn more Δ = absolute <relative> (impact), ø = not affected, ? = missing data Powered by Codecov. Last update 324c9b0...c92437c. Read the comment docs.

[Maillol]

I'm afraid that the better way to increase the interoperability whit other tools is to provide a class inherited from object - a mixin - designed to be combined with web.View or subclasses of web.View

aiohttp-pydantic can provide.

PydanticMixin and PydanticView where PydanticView will be defined as:

class PydanticView(PydanticMixin, web.View):
    ...

If the user need to use aiohttp-pydantic with existing View it can do:

class MyExistingViewWithPydantic(PydanticMixin, MyExistingView):
    ...

[Maillol]

Merged with https://github.com/Maillol/aiohttp-pydantic/pull/16 after refactoring