Cannot return null for non-nullable field , Debugger dosen't show null [duplicate] - graphql

Question

This question already has answers here:
Why does a GraphQL query return null?
(6 answers)
Closed 2 years ago.
I have this schema.graphql
### This file was generated by Nexus Schema
### Do not make changes to this file directly
type AuthPayload {
token: String!
users: users!
}
scalar DateTime
type Mutation {
login(email: String, password: String): AuthPayload!
signup(CREATED_BY: String, EMAIL: String, FIRST_NAME: String, IS_ACTIVE: Boolean, PASSWORD: String, USERNAME: String): AuthPayload!
}
type Query {
me: users
}
type users {
CREATED_BY: String!
CREATED_ON: DateTime
EMAIL: String!
FIRST_NAME: String!
id: Int!
IS_ACTIVE: Boolean!
LAST_NAME: String
MODIFIED_BY: String
MODIFIED_ON: DateTime
ORGANIZATION_ID: String
PASSWORD: String!
PHONE: String
USERNAME: String!
}
mutations :-
const Mutation = mutationType({
definition(t) {
t.field('signup', {
type: 'AuthPayload',
args: {
FIRST_NAME: stringArg({ nullable: true }),
EMAIL: stringArg(),
PASSWORD: stringArg(),
IS_ACTIVE: booleanArg(),
USERNAME: stringArg(),
CREATED_BY: stringArg(),
},
resolve: async (parent, { FIRST_NAME, EMAIL, PASSWORD ,IS_ACTIVE ,USERNAME,CREATED_BY }, ctx) => {
const hashedPassword = await hash(PASSWORD, 10)
const user = await ctx.prisma.users.create({
data: {
FIRST_NAME,
EMAIL,
PASSWORD: hashedPassword,
IS_ACTIVE,
USERNAME,
CREATED_BY
},
})
return {
token: sign({ userId: user.id }, APP_SECRET),
user,
}
},
})
t.field('login', {
type: 'AuthPayload',
args: {
email: stringArg(),
password: stringArg(),
},
resolve: async (parent, { email, password }, context) => {
const user = await context.prisma.users.findOne({
where: {
EMAIL : email,
},
})
if (!user) {
return new Error(`No user found for email: ${email}`)
}
const passwordValid = await compare(password, user.PASSWORD)
if (!passwordValid) {
return new Error('Invalid password')
}
const token = await sign({ userId: user.id }, APP_SECRET)
return {
token ,
user,
}
},
})
},
})
My problem is when i try to mutate the login method with token return value , it works perfectly and here is my mutation
mutation{
login(email :"dondala422#hotmail.com" password :"aa")
{
token
}
}
Response
{
"data": {
"login": {
"token": "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJ1c2VySWQiOjMyLCJpYXQiOjE1OTcxMDY0OTd9.d1Ra32ArCXumBfzg2vE1-xeea21cAkNwWBJPm3U3akM"
}
}
}
As shown . this works perfectly . now as mentioned the AuthPayload return the token and the users type
when i try to mutate with user :-
mutation{
login(email :"dondala422#hotmail.com" password :"aa")
{
token
users{
USERNAME
FIRST_NAME
}
}
}
it gives me this error
{
"errors": [
{
"message": "Cannot return null for non-nullable field AuthPayload.users.",
"locations": [
{
"line": 4,
"column": 5
}
],
"path": [
"login",
"users"
],
"extensions": {
"code": "INTERNAL_SERVER_ERROR",
"exception": {
"stacktrace": [
"Error: Cannot return null for non-nullable field AuthPayload.users.",
" at completeValue (C:\\Users\\donda\\Desktop\\New folder (3)\\prisma-examples\\javascript\\graphql-auth - Copy\\node_modules\\graphql\\execution\\execute.js:595:13)",
" at completeValueCatchingError (C:\\Users\\donda\\Desktop\\New folder (3)\\prisma-examples\\javascript\\graphql-auth - Copy\\node_modules\\graphql\\execution\\execute.js:530:19)",
" at resolveField (C:\\Users\\donda\\Desktop\\New folder (3)\\prisma-examples\\javascript\\graphql-auth - Copy\\node_modules\\graphql\\execution\\execute.js:461:10)",
" at executeFields (C:\\Users\\donda\\Desktop\\New folder (3)\\prisma-examples\\javascript\\graphql-auth - Copy\\node_modules\\graphql\\execution\\execute.js:297:18)",
" at collectAndExecuteSubfields (C:\\Users\\donda\\Desktop\\New folder (3)\\prisma-examples\\javascript\\graphql-auth - Copy\\node_modules\\graphql\\execution\\execute.js:748:10)",
" at completeObjectValue (C:\\Users\\donda\\Desktop\\New folder (3)\\prisma-examples\\javascript\\graphql-auth - Copy\\node_modules\\graphql\\execution\\execute.js:738:10)",
" at completeValue (C:\\Users\\donda\\Desktop\\New folder (3)\\prisma-examples\\javascript\\graphql-auth - Copy\\node_modules\\graphql\\execution\\execute.js:626:12)",
" at completeValue (C:\\Users\\donda\\Desktop\\New folder (3)\\prisma-examples\\javascript\\graphql-auth - Copy\\node_modules\\graphql\\execution\\execute.js:592:21)",
" at C:\\Users\\donda\\Desktop\\New folder (3)\\prisma-examples\\javascript\\graphql-auth - Copy\\node_modules\\graphql\\execution\\execute.js:527:16"
]
}
}
}
],
"data": null
}
i tried to attach the debugger to see where is the null occur
and i didn't found any nullable values
here is a picture of vscode before return value , the token and user object are defined
VSCode Debugger picture

Answer 1

The object returned inside your resolver includes a property named user, but your field is named users. Since users is undefined, it resolves to null, but the field is non-nullable, so an error is thrown instead.