TwForm

@code {
    private readonly SignupModel signup = new();
    private readonly string[] plans = ["Free", "Pro", "Team"];
    private bool signupSaved;
    
    private void SaveSignup() => signupSaved = true;
    
    private sealed class SignupModel
    {
        [Required(ErrorMessage = "Enter your name")]
        public string? Name { get; set; }
    
        [Required(ErrorMessage = "Enter your email address")]
        [EmailAddress(ErrorMessage = "Enter an email address in the correct format, like [email protected]")]
        public string? Email { get; set; }
    
        [Required(ErrorMessage = "Choose a plan")]
        public string? Plan { get; set; }
    
        [Range(typeof(bool), "true", "true", ErrorMessage = "Agree to the terms to continue")]
        public bool AcceptTerms { get; set; }
    }
}

@code {
    private readonly AddressModel address = new();
    
    private sealed class AddressModel
    {
        [Required(ErrorMessage = "Enter the street")]
        public string? Street { get; set; }
    
        [Required(ErrorMessage = "Enter the town or city")]
        public string? Town { get; set; }
    
        [Required(ErrorMessage = "Enter a postcode")]
        [RegularExpression(@"^[A-Za-z]{1,2}\d[A-Za-z\d]? ?\d[A-Za-z]{2}$", ErrorMessage = "Enter a real postcode, like SW1A 1AA")]
        public string? Postcode { get; set; }
    }
}

@code {
    private readonly AccountModel account = new();
    private bool accountSaved;
    private static readonly string[] _takenUsernames = ["admin", "root", "twblazor"];
    
    private static Task<string?> CheckUsernameAsync(string? username) =>
        Task.FromResult(username is not null && _takenUsernames.Contains(username.Trim().ToLowerInvariant())
            ? "That username is taken. Try another."
            : null);
    
    private sealed class AccountModel
    {
        [Required(ErrorMessage = "Enter a username")]
        [StringLength(20, MinimumLength = 3, ErrorMessage = "Usernames are 3 to 20 characters long")]
        public string? Username { get; set; }
    
        [Range(18, 120, ErrorMessage = "You must be 18 or over")]
        public int Age { get; set; }
    }
}

@code {
    private readonly BookingModel booking = new();
    private readonly List<TwBlazor.Models.RadioGroupItem<string>> rooms =
    [
        new() { Label = "Single", Value = "single" },
        new() { Label = "Double", Value = "double" },
        new() { Label = "Suite", Value = "suite" }
    ];
    
    private sealed class BookingModel
    {
        [Required(ErrorMessage = "Choose a room")]
        public string? Room { get; set; }
    
        [Required(ErrorMessage = "Enter your arrival date")]
        public string? Arrival { get; set; }
    
        [Range(1, 6, ErrorMessage = "Rooms take 1 to 6 guests")]
        public int Guests { get; set; } = 1;
    
        public bool Breakfast { get; set; }
    }
}

@code {
    private TwForm? contactForm;
    private readonly ContactModel contact = new();
    private string contactStatus = string.Empty;
    
    private async Task CheckContactAsync()
    {
        var valid = contactForm is not null && await contactForm.ValidateAsync();
        contactStatus = valid ? "Looks good." : "Fix the phone number first.";
    }
    
    private sealed class ContactModel
    {
        [Required(ErrorMessage = "Enter a phone number")]
        [Phone(ErrorMessage = "Enter a phone number, like 07700 900 982")]
        public string? Phone { get; set; }
    }
}

@code {
    private readonly NewsletterModel newsletter = new();
    
    private sealed class NewsletterModel
    {
        [Required(ErrorMessage = "Enter your email address")]
        [EmailAddress(ErrorMessage = "Enter an email address in the correct format, like [email protected]")]
        public string? Email { get; set; }
    }
}