Missing return annotation Error

Description

This error is thrown when a resolver and it's corresponding field don't have a return annotation, for example the following code will throw this error:

import strawberry


@strawberry.type
class Query:
    @strawberry.field
    def example(self):
        return "this is an example"


schema = strawberry.Schema(query=Query)

This happens because Strawberry needs to know the return type of the resolver to be able to generate the correct GraphQL type.

How to fix this error

You can fix this error by adding a return annotation to the resolver, for example, the following code will fix this error:

import strawberry


@strawberry.type
class Query:
    @strawberry.field
    def example(self) -> str:
        return "this is an example"


schema = strawberry.Schema(query=Query)