schema.js

const { 
    GraphQLSchema, 
    GraphQLObjectType, 
    GraphQLInt,
    GraphQLString,
    GraphQLList,
    GraphQLID,
    GraphQLNonNull
} = require('graphql');

const TicketType = new GraphQLObjectType({
    name: 'TicketType',
    fields: {
      id: {
        type: GraphQLString
      },
      message: {
        type: GraphQLString
      }
    }
  });
  
  const MemberType = new GraphQLObjectType({
    name: 'MemberType',
    fields: {
      id: {
        type: GraphQLInt
      },
      name: {
        type: GraphQLString
      },
      tickets: {
        type: new GraphQLList(TicketType),
        resolve(member) {
          return [
            {id: 1, message: `Member: ${member.id}, Ticket: 1`},
            {id: 2, message: `Member: ${member.id}, Ticket: 2`}
          ];
        }
      }
    }
  });
  
  const ProjectType = new GraphQLObjectType({
    name: 'ProjectType',
    fields: {
      id: {
        type: GraphQLInt
      },
      name: {
        type: GraphQLString
      },
      members: {
        type: new GraphQLList(MemberType),
        resolve(project) {
          return [
            {id: 1, name: `Project: ${project.id}, Member: 1`},
            {id: 2, name: `Project: ${project.id}, Member: 2`}
          ];
        }
      }
    }
  });
  
  const RootType = new GraphQLObjectType({
    name: 'RootType',
    fields: {
      projects: {
        type: new GraphQLList(ProjectType),
        resolve() {
          return [
            {id: 1, name: `Project 1`},
            {id: 2, name: `Project 2`}
          ];
        }
      },
      project: {
        type: ProjectType,
        args: {
          id: {
            type: new GraphQLNonNull(GraphQLID)
          }
        },
        resolve(parent, {id}) {
          return {id: id, name: `Project ${id}`}
        }
      }
    }
  });

module.exports = new GraphQLSchema({
    query: RootType
});