public async Task <AddUserResource> Handle(AddUserCommand request, CancellationToken cancellationToken)
{
if (_dataContext.Users.Any(x => x.Username == request.Username))
{
return(new AddUserResource(null, "Username is already taken"));
}
var user = new User()
{
Username = request.Username
};
user.PasswordHash = _passwordHasher.HashPassword(request.Password);
_dataContext.Users.Add(user);
await _dataContext.SaveChangesAsync();
return(new AddUserResource(UserResource.FromUser(user)));
}