Proxito: better way to pass current version/project down to the middleware

[stsewd]

What's the problem this feature will solve?

Right now we are passing only the slug of the version/project, if the middleware needs to have access to the object itself, it needs to re-fetch it from the database.

For example in

readthedocs.org/readthedocs/proxito/middleware.py

Lines 296 to 306 in 7667580

	if project_slug:
	project = Project.objects.get(slug=project_slug)
	# Check for the feature flag
	if project.has_feature(Feature.HOSTING_INTEGRATIONS):
	addons = True
	else:
	# Check if the version forces injecting the addons (e.g. using `build.commands`)
	version = (
	project.versions.filter(slug=version_slug).only("addons").first()
	)

Describe the solution you'd like

Pass the object that we already have from using the unresolver / doc serving views

Alternative solutions

None

Additional context

We have several TODOs around this

readthedocs.org/readthedocs/proxito/views/serve.py

Lines 83 to 84 in 7667580

	# TODO: find a better way to pass this to the middleware.
	request.path_project_slug = project.slug

We can't fully implement this untill we have migrated all projects to use the new proxito implementation, since the old one doesn't always have access to the object itself

readthedocs.org/readthedocs/proxito/views/utils.py

Lines 117 to 118 in 7667580

	request.path_project_slug = final_project.slug
	request.path_version_slug = version_slug

This is also somewhat related to #10124, and any other things that make use of those attributes from the middleware.

[humitos]

Pass the object that we already have from using the unresolver / doc serving views

What's the object you mean here? The Project itself? If that's what you are thinking, I'd like to talk about this a little more because I'd prefer to avoid having "multiple variables" injected in the request. Instead, I'd like to have one readthedocs object that we control and where we can add as much data as we need. This way, we always know what we are inject and where to look for it. I mentioned this before in some of the refactor PRs you worked on.

Having one and only one object will help us to when parsing the code to find out where we are injecting things. Right now, it's hard to answer that question with a simple grep or similar tools.

As an example,

request.readthedocs = RequestData(
  initial=request.readthedocs, 
  project=self.project,   # may not be needed if we pass the `unresolved_url`, tho
  unresolved_url=unresolved_url,
)

The initial allows us to initialize with data we already have in the request and override/add only the new fields we want. What do you think of an approach similar to this?

[stsewd]

Scoping it is fine, not sure we need initial, we can just override the attribute we need, we can probably start by injecting the project and version, we don't always have the unresolved URL available.

[humitos]

I just want to note here that I found myself (while working on #11205) wanting to share the Resolver() instance all across the request. This is because checking the canonical domain and other stuffs could be cached that way.