php The GraphQL-powered API with Symfony has been successfully developed, providing a robust and efficient way to manage online book store data. The API utilizes the Symfony framework and the Overblog GraphQL Bundle to create a schema for the author and book entities, as well as defining queries and mutations to interact with the data. The QueryService and MutationService classes are used to handle the requests and provide the necessary responses, while the CustomResolverMap class maps the resolver functions to the corresponding fields in the schema. The API can be tested using the GraphiQL interface, allowing developers to interact with the data and validate the functionality of the API.