Flask

Strawberry comes with a basic Flask integration. It provides a view that you can use to serve your GraphQL schema:

from flask import Flask
from strawberry.flask.views import GraphQLView

from api.schema import schema
 
app = Flask(__name__)

app.add_url_rule(
    "/graphql",
    view_func=GraphQLView.as_view("graphql_view", schema=schema),
)

if __name__ == "__main__":
    app.run()

If you'd prefer to use an asynchronous view you can instead use the following import which has the same interface as GraphQLView. This is helpful if using a dataloader.

from strawberry.flask.views import AsyncGraphQLView

Options

The GraphQLView accepts two options at the moment:

• schema: mandatory, the schema created by strawberry.Schema.
• graphiql: optional, defaults to True, whether to enable the GraphiQL interface.
• allow_queries_via_get: optional, defaults to True, whether to enable queries via GET requests

Extending the view

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

• get_context(self, response: Response) -> Any
• get_root_value(self) -> Any
• process_result(self, result: ExecutionResult) -> GraphQLHTTPResponse
• encode_json(self, response_data: GraphQLHTTPResponse) -> str

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. By default; the Response object from flask is injected via the parameters.

class MyGraphQLView(GraphQLView):
    def get_context(self, response: Response) -> Any:
        return {"example": 1}


@strawberry.type
class Query:
    @strawberry.field
    def example(self, info: 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.

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 MyGraphQLView(GraphQLView):
    def get_root_value(self) -> 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 execution result.

from strawberry.http import GraphQLHTTPResponse
from strawberry.types import ExecutionResult

from graphql.error.graphql_error import format_error as format_graphql_error


class MyGraphQLView(GraphQLView):
    def process_result(self, result: ExecutionResult) -> GraphQLHTTPResponse:
        data: GraphQLHTTPResponse = {"data": result.data}

        if result.errors:
            data["errors"] = [format_graphql_error(err) 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(GraphQLView):
    def encode_json(self, data: GraphQLHTTPResponse) -> str:
        return json.dumps(data, indent=2)