ASP.NET核心2.2剃刀页面- IP地址的用户输入验证

@page
@model IndexModel
@{
    ViewData["Title"] = "IP地址验证";
}

<h1>IP地址验证</h1>

<form method="post">
    <div class="form-group">
        <label for="ipAddress">IP地址:</label>
        <input type="text" class="form-control" id="ipAddress" name="ipAddress" required>
        <span asp-validation-for="ipAddress" class="text-danger"></span>
    </div>
    <button type="submit" class="btn btn-primary">验证</button>
</form>

@if (Model.IsValid)
{
    <div class="alert alert-success" role="alert">
        IP地址合法！
    </div>
}
else if (Model.IsValid == false)
{
    <div class="alert alert-danger" role="alert">
        IP地址不合法！
    </div>
}

@functions {
    public class IndexModel : PageModel
    {
        [BindProperty]
        [RegularExpression(@"^((25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.){3}(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)$")]
        public string ipAddress { get; set; }

        public bool? IsValid { get; set; }

        public void OnPost()
        {
            IsValid = ModelState.IsValid;
        }
    }
}