Context

Context is how you can share information between resolvers. By default when a request comes in cannula will create a context instance with the request as an attribute. Then this is added to the GraphQLResolve info and passed as the second argument to resolvers.

Example Resolver:

@api.query
def get_something(parent: Any, info: ResolveInfo[Context]):
    original_request = info.context.request
    if not can_access_something(original_request):
        raise AccessDenied("you do not have permission!")
    return get_something()

Context API Docs

class cannula.context.Context(request)

Default Context Base

Subclasses should implement a handle_request method to provide any extra functionality they need.

class cannula.context.ResolveInfo(field_name: str, field_nodes: List[FieldNode], return_type: GraphQLOutputType, parent_type: GraphQLObjectType, path: Path, schema: GraphQLSchema, fragments: Dict[str, FragmentDefinitionNode], root_value: Any, operation: OperationDefinitionNode, variable_values: Dict[str, Any], context: Any, is_awaitable: Callable[[Any], bool])

This class is strictly to help with type checking. You can use this as the info arg in a revolver to assist with type hints and code completion:

import typing
import cannula

class CustomContext(cannula.Context):
    widgets = widget_datasource()

@api.query
def get_widgets(
    parent: typing.Any,
    info: cannual.ResolveInfo[CustomContext],
) -> typing.List[Widget]:
    # type checker will be able to verify `get_widgets`
    # has the correct return type `list[Widget]`
    return info.context.widgets.get_widgets()