MvvmCross綁定到TextInputLayout的Error屬性

Question

我正在嘗試簡化一項活動的數據驗證，該活動要輸入大量控件（約10個）。 每個edittext控件都有一個唯一的驗證錯誤，因此我決定使用TextInputLayout小部件驗證支持的方法。 所以我的布局如下：

<android.support.design.widget.TextInputLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    app:errorEnabled="true"
    local:MvxBind="Error PhoneNumberError">
    <android.support.design.widget.TextInputEditText
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        local:MvxBind="Text PhoneNumber" />
</android.support.design.widget.TextInputLayout>

為了實現這一點，我創建了一個自定義綁定，一個非常簡單的綁定：

public class TextInputLayoutErrorBinding : MvxAndroidTargetBinding
{
    public const string TextInputLayoutErrorProperty = "Error";

    public TextInputLayoutErrorBinding(TextInputLayout view) 
        : base(view)
    {
    }

    public override System.Type TargetType
    {
        get { return typeof(string); }
    }

    public override MvxBindingMode DefaultMode
    {
        get { return MvxBindingMode.OneWay; }
    }

    protected override void SetValueImpl(object target, object value)
    {
        var view = (TextInputLayout)target;
        var error = (string)value;
        if (view == null)
            return;

        view.Error = error;
    }
}

並在我的Setup.FillTargetFactories注冊

 registry.RegisterCustomBindingFactory<TextInputLayout>(TextInputLayoutErrorBinding.TextInputLayoutErrorProperty, (layout) => new TextInputLayoutErrorBinding(layout));

不幸的是，當活動開始時，我的應用程序崩潰並出現以下錯誤：

[mono-rt] Stacktrace:
[mono-rt] 
[mono-rt]   at <unknown> <0xffffffff>
[mono-rt]   at (wrapper managed-to-native) Java.Interop.NativeMethods.java_interop_jnienv_call_nonvirtual_object_method_a (intptr,intptr&,intptr,intptr,intptr,Java.Interop.JniArgumentValue*) <0x00057>
[mono-rt]   at Java.Interop.JniEnvironment/InstanceMethods.CallNonvirtualObjectMethod (Java.Interop.JniObjectReference,Java.Interop.JniObjectReference,Java.Interop.JniMethodInfo,Java.Interop.JniArgumentValue*) [0x00074] in <bd30a18775d94dc8b6263aecd1ca9077>:0
[mono-rt]   at Java.Interop.JniPeerMembers/JniInstanceMethods.InvokeVirtualObjectMethod (string,Java.Interop.IJavaPeerable,Java.Interop.JniArgumentValue*) [0x0005f] in <bd30a18775d94dc8b6263aecd1ca9077>:0
[mono-rt]   at Android.Views.LayoutInflater.Inflate (int,Android.Views.ViewGroup,bool) [0x00061] in <9ab9faae1b4b4f0da28e7c4ac61e2c78>:0
[mono-rt]   at MvvmCross.Binding.Droid.Views.MvxLayoutInflater.Inflate (int,Android.Views.ViewGroup,bool) [0x00042] in <6a0c851a22864d0993089d65320a630c>:0
[mono-rt]   at MvvmCross.Binding.Droid.BindingContext.MvxAndroidBindingContext.CommonInflate (int,Android.Views.ViewGroup,bool) [0x00015] in <6a0c851a22864d0993089d65320a630c>:0
[mono-rt]   at MvvmCross.Binding.Droid.BindingContext.MvxAndroidBindingContext.BindingInflate (int,Android.Views.ViewGroup,bool) [0x00004] in <6a0c851a22864d0993089d65320a630c>:0
[mono-rt]   at MvvmCross.Binding.Droid.BindingContext.MvxAndroidBindingContext.BindingInflate (int,Android.Views.ViewGroup) [0x00004] in <6a0c851a22864d0993089d65320a630c>:0
[mono-rt]   at MvvmCross.Binding.Droid.BindingContext.MvxBindingContextOwnerExtensions.BindingInflate (MvvmCross.Binding.BindingContext.IMvxBindingContextOwner,int,Android.Views.ViewGroup) [0x0000d] in <6a0c851a22864d0993089d65320a630c>:0
[mono-rt]   at MvvmCross.Droid.Support.V7.AppCompat.MvxAppCompatActivity.SetContentView (int) [0x00003] in <76c7f3cdfddd459898d814608e83832e>:0
[mono-rt]   at Android.Views.SignupView.OnCreate (Android.OS.Bundle) [0x00009] in Android/Views/SignupView.cs:17
[mono-rt]   at Android.Support.V4.App.FragmentActivity.n_OnCreate_Landroid_os_Bundle_ (intptr,intptr,intptr) [0x00013] in <6296d3d76c5d4378959a1d9bf7205023>:0
[mono-rt]   at (wrapper dynamic-method) object.47968830-2057-4cdb-aa78-9844556333c4 (intptr,intptr,intptr) [0x00017] in <3fd174ff54b146228c505f23cf75ce71>:0
[mono-rt]   at (wrapper native-to-managed) object.47968830-2057-4cdb-aa78-9844556333c4 (intptr,intptr,intptr) [0x00022] in <3fd174ff54b146228c505f23cf75ce71>:0

我可以通過綁定驗證錯誤來實現我的目標，還是必須手動執行？

Answer 1

我發現Xamarin具有Error屬性，即使沒有任何自定義綁定，您也可以綁定到它。 像這樣：

local:MvxBind="Error PhoneNumberError"