Strawberry GraphQL FastAPI Resolvers

import strawberry
from fastapi import FastAPI
from strawberry.fastapi import GraphQLRouter

BOOKS = {'b-1': {'title': 'Designing Data', 'pages': 320}}


def get_books() -> dict:
    return BOOKS


@strawberry.type
class Book:
    id: strawberry.ID
    title: str
    pages: int


@strawberry.type
class Query:
    @strawberry.field
    def book(self, id: strawberry.ID) -> Book | None:
        record = get_books().get(str(id))
        if record is None:
            return None
        return Book(id=id, title=record['title'], pages=record['pages'])


@strawberry.type
class Mutation:
    @strawberry.mutation
    def add_book(self, title: str, pages: int) -> Book:
        new_id = f'b-{len(get_books()) + 1}'
        get_books()[new_id] = {'title': title, 'pages': pages}
        return Book(id=new_id, title=title, pages=pages)


schema = strawberry.Schema(query=Query, mutation=Mutation)

app = FastAPI()
app.include_router(GraphQLRouter(schema), prefix='/graphql')

# GraphQL 查询示例：
# query { book(id: "b-1") { title pages } }
# mutation { addBook(title: "GraphQL in Prod", pages: 240) { id } }