如何在 Xamarin 中绑定来自 ViewModel 的结果

Question

我这里有 1 个问题：How to get data from ViewModel in Xamarin，但我仍然没有解决问题。我创建了一个新的 post 并进行了一些更改。

我有：

PageOne.xaml

 <StackLayout>
      <RefreshView x:DataType="locals:ViewCustomerViewModel" Command="{Binding LoadUserinfoCommand}" IsRefreshing="{Binding IsBusy, Mode=OneWay}">
           <Label Text="{Binding Customer.Address}" />
      </RefreshView>
 </StackLayout>

PageOne.xaml.cs

  ViewCustomerViewModel viewCustomerViewModel;
  public Customer CustomerGet { get; set; }
  public PageOne()
  {
     InitializeComponent();
     BindingContext = viewCustomerViewModel = new ViewCustomerViewModel();
     viewCustomerViewModel.OnAppearing();
  }

Class 客户

 public class Customer
 {
    public string Address{ get; set; }
    ........
 }

ViewCustomerViewModel

 public class ViewCustomerViewModel:BaseCustomerViewModel
 {
    ApiServiceUserinfo apiServiceUserinfo = new ApiServiceUserinfo();
    public Command LoadUserinfoCommand { get; }
    public ObservableCollection<Customer> CustomerInfos { get; set; }
    public ViewCustomerViewModel()
    {
       LoadUserinfoCommand = new Command(async () => await ExecuteLoadUserinfoCommand());
       CustomerInfos = new ObservableCollection<Customer>();
    }

    public void OnAppearing()
    {
       IsBusy = true;
    }

    async Task ExecuteLoadUserinfoCommand()
    {
       string userget = "1";

       IsBusy = true;

       try
       {
         CustomerInfos.Clear();
         var customerList = await apiServiceUserinfo.GetCustomersInfo(userget);
         CustomerInfos.Add(customerList);
       }
       catch (Exception)
       {
         throw;
       }
       finally
       {
         IsBusy = false;
       }
    }
 }

我得到了结果CustomerInfos.Add(customerList);

但是<Label Text="{Binding Customer.Address}" />没有得到结果

请再帮我解答清楚。谢谢。

更新

ViewCustomerViewModel

 public class ViewCustomerViewModel:BaseCustomerViewModel
 {
    ApiServiceUserinfo apiServiceUserinfo = new ApiServiceUserinfo();
    public Command LoadUserinfoCommand { get; set;}

    public Customer CustomerGets { get; set;}--> update

    public ViewCustomerViewModel()
    {
       LoadUserinfoCommand = new Command(async () => await ExecuteLoadUserinfoCommand());
       //CustomerGets = new Customer();
    }

    public void OnAppearing()
    {
       IsBusy = true;
    }

    async Task ExecuteLoadUserinfoCommand()
    {
       string userget = "1";

       IsBusy = true;

       try
       {
         var customerList = await apiServiceUserinfo.GetCustomersInfo(userget);
         CustomerGets = customerList;
       }
       catch (Exception)
       {
         throw;
       }
       finally
       {
         IsBusy = false;
       }
    }
 }

PageOne.xaml

<StackLayout>
   <RefreshView x:DataType="locals:ViewCustomerViewModel" Command="{Binding LoadUserinfoCommand}" IsRefreshing="{Binding IsBusy, Mode=OneWay}">
       <Label Text="{Binding CustomerGets.Address}" />
   </RefreshView>
</StackLayout>

Answer 1

我们需要调用OnPropertyChanged方法来通知setter方法中属性的变化。

private Customer customerGets;
public Customer CustomerGets { 
  get { return customerGets; }
  set { 
          customerGets = value;
          NotifyPropertyChanged();     //the method is declared in BaseCustomerViewModel 
      }
}

确保 BaseCustomerViewModel 已经实现 INotifyPropertyChanged ，类似的东西

 public class BaseCustomerViewModel : INotifyPropertyChanged
    {
        public event PropertyChangedEventHandler PropertyChanged;

        public void NotifyPropertyChanged([CallerMemberName] String propertyName = "")
        {
            PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
        }
    }

如何在 Xamarin 中绑定来自 ViewModel 的结果

How to Binding Result from ViewModel in Xamarin

xamarin