2020-Jan answer

The current answer to getting the fields requested in a GraphQL query, is to use the graphql-parse-resolve-info library for parsing the info parameter.

The library is "a pretty complete solution and is actually used under the hood by postgraphile", and is recommended going forward by the author of the other top library for parsing the info field, graphql-fields.

Use graphql-fields

Apollo server example

const rootSchema = [`    type Person {        id: String!        name: String!        email: String!        picture: String!        type: Int!        status: Int!        createdAt: Float        updatedAt: Float    }    schema {    query: Query    mutation: Mutation    }`];const rootResolvers = {    Query: {        users(root, args, context, info) {            const topLevelFields = Object.keys(graphqlFields(info));            return fetch(`/api/user?fields=${topLevelFields.join(',')}`);        }    }};const schema = [...rootSchema];const resolvers = Object.assign({}, rootResolvers);// Create schemaconst executableSchema = makeExecutableSchema({    typeDefs: schema,    resolvers,});

Sure you can. This is actually the same functionality that is implemented on join-monster package for SQL based db's. There's a talk by their creator: https://www.youtube.com/watch?v=Y7AdMIuXOgs

Take a look on their info analysing code to get you started - https://github.com/stems/join-monster/blob/master/src/queryASTToSqlAST.js#L6-L30

Would love to see a projection-monster package for us mongo users :)

UPDATE:There is a package that creates a projection object from info on npm: https://www.npmjs.com/package/graphql-mongodb-projection