ASGI

Strawberry comes with a basic ASGI integration. It provides an app that you can use to serve your GraphQL schema. Before using Strawberry’s ASGI support make sure you install all the required dependencies by running: 

pip install 'strawberry-graphql[asgi]'

Once that's done you can use Strawberry with ASGI like so: 

# server.py
from strawberry.asgi import GraphQL
 
from api.schema import schema
 
app = GraphQL(schema)

Every ASGI server will accept this app instance to start the server. For example if you’re using uvicorn you run the app with uvicorn server:app

Options

The GraphQL app accepts two options at the moment:

Extending the view

We allow to extend the base GraphQL app, by overriding the following methods:

get_context

get_context allows to provide a custom context object that can be used in your resolver. You can return anything here, by default we return a dictionary with the request and the response. 

class MyGraphQL(GraphQL):
    async def get_context(
        self, request: Union[Request, WebSocket], response: Optional[Response] = None
    ) -> Any:
        return {"example": 1}
 
 
@strawberry.type
class Query:
    @strawberry.field
    def example(self, info: strawberry.Info) -> str:
        return str(info.context["example"])

Here we are returning a custom context dictionary that contains only one item called "example".

Then we use the context in a resolver, the resolver will return "1" in this case.

Setting response headers

It is possible to use get_context to set response headers. A common use case might be cookie-based user authentication, where your login mutation resolver needs to set a cookie on the response.

This is possible by updating the response object contained inside the context of the Info object. 

@strawberry.type
class Mutation:
    @strawberry.mutation
    def login(self, info: strawberry.Info) -> bool:
        token = do_login()
        info.context["response"].set_cookie(key="token", value=token)
        return True

Setting background tasks

Similarly, background tasks can be set on the response via the context: 

from starlette.background import BackgroundTask
 
 
async def notify_new_flavour(name: str): ...
 
 
@strawberry.type
class Mutation:
    @strawberry.mutation
    def create_flavour(self, name: str, info: strawberry.Info) -> bool:
        info.context["response"].background = BackgroundTask(notify_new_flavour, name)

get_root_value

get_root_value allows to provide a custom root value for your schema, this is probably not used a lot but it might be useful in certain situations.

Here’s an example: 

class MyGraphQL(GraphQL):
    async def get_root_value(self, request: Request) -> Any:
        return Query(name="Patrick")
 
 
@strawberry.type
class Query:
    name: str

Here we are returning a Query where the name is "Patrick", so we when requesting the field name we'll return "Patrick" in this case.

process_result

process_result allows to customize and/or process results before they are sent to the clients. This can be useful logging errors or hiding them (for example to hide internal exceptions).

It needs to return an object of GraphQLHTTPResponse and accepts the request and the execution results. 

from strawberry.http import GraphQLHTTPResponse
from strawberry.types import ExecutionResult
 
 
class MyGraphQL(GraphQL):
    async def process_result(
        self, request: Request, result: ExecutionResult
    ) -> GraphQLHTTPResponse:
        data: GraphQLHTTPResponse = {"data": result.data}
 
        if result.errors:
            data["errors"] = [err.formatted for err in result.errors]
 
        return data

In this case we are doing the default processing of the result, but it can be tweaked based on your needs.

encode_json

encode_json allows to customize the encoding of the JSON response. By default we use json.dumps but you can override this method to use a different encoder. 

class MyGraphQLView(GraphQL):
    def encode_json(self, data: GraphQLHTTPResponse) -> str:
        return json.dumps(data, indent=2)

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