Why am I getting "Cannot return null for non-nullable field User.sentEmail."?

Question

I understand that I would receive this error if the field I am trying to call is null, but when I do a create email, that email's id does gets saved in the user. But when I try to query that user using the following query

 query all { users{ sentEmail{ sender emailbody recipient } } } }

I get the error "Cannot return null for non-nullable field User.sentEmail." If there is a id in sentEmail, why am I getting this error

Resolver

 const { Email, User } = require('../models') const resolvers = { Query: { users: async () => { return await User.find({}).populate('emails'); }, emails: async (parent, { email }) => { const params = email? { email }: {}; return await Email.find(params).sort({ sentDate: -1 }); }, }, Mutation: { addemail: async (parent, {sender, recipient, subject, emailbody}) => { const newemail = await Email.create({ sender, recipient, subject, emailbody}); await User.findOneAndUpdate( { email: newemail.sender }, { $addToSet: { sentEmails: newemail._id }} ) await User.findOneAndUpdate( { email: newemail.recipient }, { $addToSet: { receivedEmails: newemail._id }} ) return newemail }, addUser: async (parent, { firstName, lastName, email, password }) => { const user = await User.create({ firstName, lastName, email, password }, {new: true}) }, } }; module.exports = resolvers

typeDefs

 const { gql } = require('apollo-server-express'); const typeDefs = gql` type User { _id: ID firstName: String lastName: String email: String password: String sentEmail: [Email]: } type Email { _id: ID sender: String recipient: String emailbody: String sentDate: String } type Query { users: [User] emails(email: String): [Email] } type Mutation { addemail(sender, String:, recipient: String,: subject: String: emailbody, String:), Email addUser(firstName: String,: lastName: String;. email; String!, password: String! ): User } `; module.exports = typeDefs;

Answer 1

Please check your response from the resolver. Seems it is returning the value of sentEmail field as null or sentEmail field is not present in your response json.