Xamarin窗体视图不会更新自定义类

问题描述：

我使用Prism.Unity.Forms与Xamarin这个项目。如何在Client.Id属性更改时更新视图？当我将{Binding Client.Id}（Guid对象）的XAML更改为{Binding Client.Name}（字符串）时，视图更新。Xamarin窗体视图不会更新自定义类

public class CreateClientViewModel : BindableBase 
{ 
    private Client _client; 
    public Client Client { 
     get => _client; 
     set => SetProperty(ref _client, value); 
    } 

    private async void FetchNewClient() 
    { 
     Client = new Client{ 
      Id = new Guid.Parse("501f1302-3a45-4138-bdb7-05c01cd9fe71"), 
      Name = "MyClientName" 
     }; 
    } 
}

这工作

<Entry Text="{Binding Client.Name}"/>

这不

<Entry Text="{Binding Client.Id}"/>

我知道ToString方法被调用的Client.Id属性，因为我在一个自定义类包裹Guid和重载了ToString方法，但该视图仍然不更新。

public class CreateClientViewModel : BindableBase 
{ 
    private Client _client; 
    public Client Client { 
     get => _client; 
     set => SetProperty(ref _client, value); 
    } 

    //This method will eventually make an API call. 
    private async void FetchNewClient() 
    { 
     Client = new Client{ 
      Id = new ClientId{ 
       Id = new Guid.Parse("501f1302-3a45-4138-bdb7-05c01cd9fe71") 
      }, 
      Name = "MyClientName" 
     }; 
    } 
} 

public class ClientId 
{ 
    public Guid Id { get; set } 

    public override string ToString() 
    { 
     //This method gets called 
     Console.WriteLine("I GET CALLED"); 
     return Id.ToString(); 
    } 
}

务必使您的客户端执行INotifyPropertyChanged –

答

使用Converter解决了这个问题，但我无法解释为什么。两种方法都被称为Guid.ToString方法。

<Entry Text="{Binding Client.Id, Converter={StaticResource GuidConverter}}"/>

public class GuidConverter : IValueConverter 
{ 
    public object Convert() 
    { 
     var guid = (Guid) value; 
     return guid.ToString(); 
    } 

    public object ConvertBack(){...} 
}

然后我注册的转换器在App.xaml

<ResourceDictionary> 
    <viewHelpers:GuidConverter x:Key="GuidConverter" /> 
</ResourceDictionary>

Xamarin窗体视图不会更新自定义类

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