Write resolvers for nested type definitions

Question

Suppose I have following type definition for my GraphQL API:

const typeDef = `
    type Book {
         title: String
         author: Author
         likes: Int
    }

    type Author {
         id: String
         name: String
         age: Int
         books: [Book]
    }

    type Query{
         books(authorid: String!): Book
    }
`

Then, how many resolvers do I need for this? Should I handle this query request with only one resolver books and return all books and author info or should I make many resolvers such as Query -> books, Book -> author and Author -> books? I am not sure how the modular schema and resolver works together.

Answer 1

No matter how many type(Book, Author etc) or input you use you need to provide .

const schema = ` 
    type Mutation {
        mutatePost(postId:Int) :Int
    }
    type Query {
        hello: String
        posts: [String]
        books(authorId: String!): Book
    }
  `

You need to use same name as you defined in Query must be same in resolver

   const resolvers = {
        Query: {
        async hello() {
            return 'Hello';
        },
        async posts() {
            return ['Hello', 'World];
        },
        async books(_, { authorId }) {
            //Return data which you is defined in type Book
            //return Book
        }
        },
        Mutation: {
            async mutatePost(_, {
            postId
            }, context) {
            //return Integer
            }
        },
    }

Only thing every Query and Mutation need queryResolver and mutationResolver