Hey folks, I while ago I wrote down some ideas on how we can add support for query complexity. For this we'll need two things:

1. An extensions that calculates the costs based on an operation
2. Support for customising the costs based on fields/arguments

For customising costs on fields and arguments I was thinking about something like this:

import strawberry

@strawberry.type
class Query:
    @strawberry.field(cost=2)
    def expensive_list(self, limit: Annotated[int, strawberry.argument(cost_multiplier=1)]) -> list[str]:
        return ["Item"] * limit

Here we are saying that each individual item in the expensive_list field costs 2, and the total is a multiplication between the field cost and the limit, so the result would be:

field_cost × limit × 1

We can also have defaults like this:

class StrawberryConfig:
    # Existing attributes and methods ...
    
    default_argument_cost_multiplier: Dict[str, Union[int, float]] = {
        "limit": 1,
        "first": 1, # probably not needed, but worth showing as an example
        "last": 1
    }

default_argument_cost_multiplier is a map between argument name and their multiplier, though I don't like the name that much.

What do you think?