Standardise context creation and access

[jkimbo]

At the moment the Django and Sanic integrations return a custom dataclass from the default implementation of get_context. This allows gives a nicer developer experience because you can access properties via dict or attribute notation. However if you override the get_context method to customise the context and return a dictionary (which is what the docs recommend) it can break assumptions made elsewhere.

I propose that we standardise how the context is created by wrapping whatever is returned from get_context in a StrawberryContext wrapper class. This would also allow us to store internal data in the context which might be useful in custom fields or extensions.

Something like this:

class MyGraphQLView(GraphQLView):
	def get_context(self, request, response):
		return {
			"request": request,
			"response": response,
			"current_time": datetime.now(),
		}

@strawberry.type
class Query:
	@strawberry.field
	def current_time(self, info) -> str:
		context = info.context  # type is StrawberryContext
		return context.current_time.isoformat()

Also I think it should be possible (and encouraged) to modify context using extensions rather than having to override the base view.

Only concern I have is how we type this. Thoughts @strawberry-graphql/core ?

[BryceBeagle]

I think this is a great idea.

Only concern I have is how we type this.

Can you elaborate on what makes typing this complicated?

[jkimbo]

Can you elaborate on what makes typing this complicated?

So if we take the example I posted you might want to type your context object like this:

class MyContext(TypedDict):
	request: Request
	response: Response
	current_time: datetime

class MyGraphQLView(GraphQLView):
	def get_context(self, request, response) -> MyContext:
		return {
			"request": request,
			"response": response,
			"current_time": datetime.now(),
		}

If you have that it's unclear how we could tell Mypy that this is ok:

@strawberry.type
class Query:
	@strawberry.field
	def current_time(self, info: Info[MyContext]) -> str:
		context = info.context.current_time  # how does Mypy know that `current_time` is an attribute on `context`?

[patrick91]

I'd just use dataclasses 😊

EDIT: we can do dataclasses and allow dict access until v1.0

[jkimbo]

Dataclasses would be good but how would you allow extra things to be added outside of the "get_context" call? For example adding things to context through extensions.

[patrick91]

Dataclasses would be good but how would you allow extra things to be added outside of the "get_context" call? For example adding things to context through extensions.

do you have any use case in mind? You can always add new property, but it might be that clean

[jkimbo]

For example injecting dataloaders or db sessions (https://strawberry.rocks/docs/guides/custom-extensions#execution-context)

[jkimbo]

IMO you should only use extensions to change context rather than having to subclass the views. The API is nicer.

[patrick91]

uh, interesting, yeah, that might be better. Not sure how to type it then if you have multiple extensions providing context.

I guess this could be where typing.Intersection could be handy (doesn't exist yet) you could do this in resolvers:

def something(info: Info[Extention1.Context & Extension2.Context]) -> str:
   ...

[jkimbo]

uh, interesting, yeah, that might be better. Not sure how to type it then if you have multiple extensions providing context.

Maybe it's just not possible 🤷 Could be a reason not to allow it?

I do like the Intersection idea!

[SergeyKapshuchenko]

@jkimbo your example throws an exception for me, but I've found a solution how to fix it

from strawberry.types.info import Info as StrawberryInfo, RootValueType


@dataclass
class Context:
    request: HttpRequest
    response: HttpResponse
    user: User


Info = StrawberryInfo[Context]  # raises an exception
Info = StrawberryInfo[Context, RootValueType]  # works fine passing RootValueType

Am I right ?

[patrick91]

@SergeyKapshuchenko yes 😊

you can also do:

Info = StrawberryInfo[Context, Any]

if you don't need the type of info.root_value 😊

[SergeyKapshuchenko]

@patrick91 thank you !