Qustion

There is no way to assign constraints to user.data fields within FusionAuth, but there is an open issue that I encourage you to upvote.

You can require usernames to be unique in a tenant, using the Unique usernames setting. It is, however a feature which requires a paid plan.

Another alternative, rather than

fetching all users and then looping over users
would be to search for the username before creating the user. Using the search functionality that wouldn't require scanning all the users. You can use a transactional webhook to fail user creation if your uniqueness rules are not met.

The thing is that I am setting the user's email to enable them login and then inside data object I am setting a username for the future use, but as of now it is kinda random and automatically generated at the registration time.

So why the heck is FusionAuth SDK for Typescript returns a client response with this error is a mystery for me.

It should not do it under normal circumstances, according to my understanding you can only use email or username, and I am setting email as the way to login but username is inside the data and that should not interfere with anything IMO.

I am trying to update this user that was created automatically with Terraform:

resource "fusionauth_user" "you-say-temp-user" {
  tenant_id                = fusionauth_tenant.you-say-tenant.id
  email                    = "souma.kazuya@you-say.com"
  first_name               = "Souma"
  last_name                = "Kazuya"
  password                 = "souma.kazuya"
  skip_verification        = true
  password_change_required = false
  data = jsonencode({
    username : "souma_kazuya"
  })
}

And here is the TS code that I am using to update it, as you can see I am not even touching username:

await this.fusionAuthClient.updateUser(id, {
  user: {
    lastName: updateUserInfoDto.lastName,
    firstName: updateUserInfoDto.firstName,
  },
});

It would be really great if someone could leave a comment setting myself aside ありがとう.

It's error message: You must specify either the [user.email] or [user.username] property. If you are emailing the user you must specify the [user.email].

Then the other option is a vulgar way of doing it, fetching all users and then looping over users and comparing the user.data.username with the new one. It is not gonna work in a medium-size or large user base app.

I can think of one more option which is saving all usernames in my MongoDB database which can work but is not what I would volunteer for it.

Any suggestion?