next-auth question about credentials provider - next-auth

Question

next-auth credentials provider only has methods for signIn and signOut, which has led me to think I might be missing something about the purpose of the credentials provider in general.
shouldn't there also be a log in method?
The way it is, in order to do login and signup separately, I can only use signIn for both.
That would almost be ok because I could conditionally check if a user has an account inside of the CredentialsProvider method, and then login or signup conditionally.
The problem is that then the login form also works as a sign up form if the user were to to enter the wrong username for instance... it would just see that account doesn't exist and sign them up.
Obviously that is very bad.
Here is the CredentialsProvider method that gets called when you use 'signIn'
export default CredentialsProvider({
name: '',
credentials: {
email: { label: 'Username', type: 'text', placeholder: 'email' },
password: { label: 'Password', type: 'password' }
},
async authorize(credentials, req) {
if (!credentials?.email || !credentials?.password) {
throw new Error('Invalid Credentials')
}
//conditionally query or signup mutation here depending on if the credentials exists
const signIn = UserOperations.Mutations.signIn
await client.query<SignUpResponse, SignUpInput>({
query: signIn,
variables: {
email: credentials.email,
password: credentials.password
}
})
const signUp = UserOperations.Mutations.signUp
const response = await client.mutate<SignUpResponse, SignUpInput>({
mutation: signUp,
variables: {
email: credentials.email,
password: credentials.password
}
})
const { data } = response
const user = data?.signUp
if (user) {
return user
}
return null
}
})
And you then you call it from your login component or sign up component like this:
await signIn('credentials', {
redirect: false,
email,
password,
callbackUrl: `${window.location.origin}`
})
But I don't see any way to distinguish where it's being called from. Isn't the point of credentials to be able to have login and sign up separate?

Answer 1

I figured it out. The idea is to use CredentialsProvider twice, once for signup and once for login.
You can specify which provider gets called with the id property in the provider.
const signUp = CredentialsProvider({
id: 'sign-up-provider',
credentials: {
email: { label: 'Username', type: 'text', placeholder: 'email' },
password: { label: 'Password', type: 'password' }
},
//authorize will be called whether this is signUp or signIn
async authorize(credentials, req) {
if (!credentials?.email || !credentials?.password) {
throw new Error('Invalid Credentials')
}
const signUp = UserOperations.Mutations.signUp
const response = await client.mutate<SignUpResponse, SignUpInput>({
mutation: signUp,
variables: {
email: credentials.email,
password: credentials.password
}
})
const { data } = response
const user = data?.signUp
if (user) {
return user
}
return null
}
})
export default signUp
and then instead of passing in 'credentials' to signIn you can pass in the custom id.
await signUp('sign-up-provider', {
redirect: false,
email,
password,
callbackUrl: `${window.location.origin}`
})
Do the same for a login provider, and then add both providers in the nextAuth providers array.