Validation 仅当用户输入发生更改时才进行反应UI验证
我是ReactiveUI的新手,所以我一直坚持在页面开始时显示错误消息,而不是在用户输入更改之后 我想我对ComplexRule有问题。 下面是我在ViewModel中的代码:Validation 仅当用户输入发生更改时才进行反应UI验证,validation,xamarin.forms,reactiveui,Validation,Xamarin.forms,Reactiveui,我是ReactiveUI的新手,所以我一直坚持在页面开始时显示错误消息,而不是在用户输入更改之后 我想我对ComplexRule有问题。 下面是我在ViewModel中的代码: public LoginViewModel(IScreen screen) { HostScreen = screen; NameRule = this.ValidationRule( viewModel => viewModel.UserNa
public LoginViewModel(IScreen screen)
{
HostScreen = screen;
NameRule = this.ValidationRule(
viewModel => viewModel.UserName,
name => name.Length > 2,
"You must specify a valid name longer then 2 sybols.");
//checks with Regexp password
PasswordRule = this.ValidationRule(
viewModel => viewModel.Password,
password => PasswordValidator.Validate(password),
"You must specify a valid password longer then 8 sybols with at least 1 digit, upper
case, lower case and special characters.");
var nameAndPasswordRules = this
.WhenAnyValue(
x => x.UserName,
x => x.Password,
(name, password) => NameRule.IsValid && PasswordRule.IsValid);
ComplexRule = this.ValidationRule(
_ => nameAndPasswordRules,
(vm, state) => !state ? "Username and Password should be both valid!" : string.Empty);
var canNavigate = this.IsValid();
NavigateToMainPage = ReactiveCommand.CreateFromObservable(() =>
{
return HostScreen.Router.NavigateAndReset.Execute(new MyTabbedViewModel(HostScreen));
}, canNavigate);
}
以下是我的观点:
public LoginView()
{
InitializeComponent();
this.WhenActivated(disposables =>
{
this.Bind(ViewModel, vm => vm.UserName, v => v.username.Text)
.DisposeWith(disposables);
this.BindValidation(ViewModel, vm => vm.NameRule, v => v.usernameErrors.Text)
.DisposeWith(disposables);
this.Bind(ViewModel, vm => vm.Password, v => v.password.Text)
.DisposeWith(disposables);
this.BindValidation(ViewModel, vm => vm.PasswordRule, v => v.passwordErrors.Text)
.DisposeWith(disposables);
this.BindCommand(ViewModel, x => x.NavigateToMainPage, x => x.loginButton)
.DisposeWith(disposables);
});
}
所以我试图在用户输入更改(密码/用户名)后实现验证,并显示适当的消息。
我从文档中选取了这个示例。我尝试了几种方法,并完成了这一种。 不确定这是否是最好的方法,但它是有效的( 如果你知道如何做得更好,我想听听你的意见 我将
null
值分配给属性
[Reactive]
public string UserName { get; set; } = null;
[Reactive]
public string Password { get; set; } = null;
所以我们假设null-意味着它从未被使用过
并将这种验证放在ValidationRule上
var name = this
.WhenAnyValue(x => x.UserName)
.Select(x => x == null || x?.Length > 2);
var password = this
.WhenAnyValue(x => x.Password)
.Select(x => x == null || PasswordValidator.Validate(x));
var nameAndPasswordRules = this
.WhenAnyValue(
x => x.UserName,
x => x.Password)
.DefaultIfEmpty()
.DistinctUntilChanged()
.SkipWhile(item => !string.IsNullOrWhiteSpace(item.Item1) && !string.IsNullOrWhiteSpace(item.Item2))
.Select(prop1 =>
!string.IsNullOrEmpty(prop1.Item1)
&& this.NameRule.IsValid
&& !string.IsNullOrEmpty(prop1.Item2)
&& this.PasswordRule.IsValid);
NameRule = this.ValidationRule(
_ => name,
(vm, state) => !state ? "You must specify a valid name longer then 2 sybols." : string.Empty);
PasswordRule = this.ValidationRule(
_ => password,
(vm, state) => !state ? "You must specify a valid password longer then 8 sybols with at least 1 digit, upper case, lower case and special characters." : string.Empty);
ComplexRule = this.ValidationRule(
_ => nameAndPasswordRules,
(vm, state) => !state ? "Username and Password should be both valid!" : string.Empty);
如您所见,我确实x==null | |…
表示跳过第一次尝试,因为用户尚未编辑条目用户名和密码属性标记为[Reactive]属性
“[Reactive]公共字符串用户名{get;set;}=string.Empty;[Reactive]公共字符串密码{get;set;}”=String.Empty;
'这个Fody的东西意味着我帮不了什么忙-我是手工做的-但是有一个DistinctUntilChanged
操作符可能对你有用。不幸的是,它不起作用,因为它不能区分null和notnull元素。所以我用了不同的方法。不确定这里的最佳实践是什么(感谢您的分享,请在三天后标记您的答案。这将帮助其他有类似问题的人。