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无法分配属性“Converter”:属性不存在,或不可分配,或值和属性之间的类型不匹配

mvvmcross xamarin.forms

Drake · 技术社区 · 6 年前

我正在用Xamarin.Forms和MvvmCross编写一个应用程序。我的转换器有问题。在我的 Core 项目:

public class BoolInverseValueConverter : MvxValueConverter<bool, bool>
{
    public bool Convert(bool value, Type targetType, CultureInfo culture, object parameter)
    {
        return !value;
    }
}

Forms 项目:

namespace MyApp.Forms.NativeConverters
{
    public class BoolInverseValueConverter : MvxNativeValueConverter<MyApp.Core.Converters.BoolInverseValueConverter>
    {
    }
}

在我的xaml中:

<Application xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
xmlns:converters="clr-namespace:MyApp.Forms.NativeConverters;assembly=MyApp.Forms"
x:Class="MyApp.Forms.App">
<Application.Resources>
    <converters:BoolInverseValueConverter x:Key="BoolInverseValueConverter" />
</Application.Resources>

<views:MvxContentPage x:TypeArguments="viewModels:LoginViewModel"
xmlns="http://xamarin.com/schemas/2014/forms" 
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml" 
xmlns:views="clr-namespace:MvvmCross.Forms.Views;assembly=MvvmCross.Forms"
xmlns:mvx="clr-namespace:MvvmCross.Forms.Bindings;assembly=MvvmCross.Forms"
xmlns:viewModels="clr-namespace:MyApp.Core.ViewModels;assembly=MyApp.Core"
xmlns:localviews="clr-namespace:MyApp.Forms.Views;assembly=MyApp.Forms"
xmlns:resx="clr-namespace:MyApp.Core.Resources;assembly=MyApp.Core"
x:Class="MyApp.Forms.Pages.LoginPage"
Title="Login">
    <ContentPage.Content>
        <localviews:UserLoginView DataContext="{Binding .}" IsVisible="{mvx:MvxBind MyBoolVariable, Converter={StaticResource BoolInverseValueConverter}}"/>
    </ContentPage.Content>
</views:MvxContentPage>

当我运行UWP应用程序时,我得到一条消息:

无法分配属性转换器:属性不存在或不存在值和属性之间的可赋值或不匹配类型

4 回复 | 直到 6 年前

fmaccaroni 6 年前

我想 MvvmCross Setup :

protected override IEnumerable<Assembly> ValueConverterAssemblies
{
    get
    {
        var toReturn = base.ValueConverterAssemblies.ToList();
        toReturn.Add(typeof(BoolInverseValueConverter).Assembly);
        return toReturn;
    }
}

嗨

Jason 6 年前

不知道MvvmCross,但在xaml文件中

<Application.Resources>

和

<converters:BoolInverseValueConverter ...>

你加了吗 <ResourceDictionary> ?

Venkat 6 年前

你的转换器应该如下所示

 public class BoolInverseValueConverter: IValueConverter
    {
        public object Convert(object value, Type targetType, object parameter, string language)
        {
            if (value == null || (value as bool?) == false)
                return Visibility.Collapsed;
            else
                return Visibility.Visible;
        }

        public object ConvertBack(object value, Type targetType, object parameter, string language)
        {
            if (value == null || (value as bool?) == false)
                return Visibility.Collapsed;
            else
                return Visibility.Visible;

        }

Drake 6 年前