Xamarin.Forms-PropertyChanged集{}未调用 [英] Xamarin.Forms - PropertyChanged set {} not called

问题描述

我有一个简单的 LoginView 和 LoginViewModel . 首先，这是View的相关代码:

I've got a simple LoginView and LoginViewModel. First, here is the related code of the View:

<StackLayout>
    <Entry
        Text="{Binding Email, Mode=TwoWay}" 
    />
    ...

这是ViewModel:

And here is the ViewModel:

public class LoginViewModel : INotifyPropertyChanged
{
    public event PropertyChangedEventHandler PropertyChanged = delegate { };

    private string _email;
    public string Email
    {
        get => _email;
        set
        {
            _email = value;
            PropertyChanged(this, new PropertyChangedEventArgs(nameof(Email)));
        }
    }
    ...
}

如果我在构造函数中说类似

If I say inside the Constructor something like

Email = "abc";

该条目肯定显示值"abc".但是，如果我更改条目中的文本，则不会触发 set {} ，因此 PropertyChanged()也不会触发.

the Entry for sure displays the value "abc". But if I change the Text inside the Entry, the set {} is not firing so the PropertyChanged() also does not.

我在这里错过了什么吗?还是必须使用BindableProperties?

Do I miss something here or do I have to use BindableProperties?

提前谢谢！

对于需要为 LoginView 定义BindingContext的任何人，下面是代码背后:

For anyone needing the definition of the BindingContext for LoginView, here is the Code-Behind:

[XamlCompilation(XamlCompilationOptions.Compile)]
public sealed partial class LoginView
{
    public LoginView()
    {
        InitializeComponent();

        // Set the ViewModel
        this.BindingContext = new LoginViewModel();
    }
}

编辑2

因此，我创建了一个Testproject，该项目只是将条目的TextProperty绑定到属性.这行得通！然后，我编辑了我现有的代码(删除了基类，简化了所有内容，等等)以简单地完成相同的基本操作……而且它不起作用.这可能是什么?

Edit 2

So I created a Testproject which simply binds the TextProperty of a Entry to a Property. This works! Then I edited my existing Code (removed Baseclasses, simplified everything, etc) to simply do the same basic thing... And it doesn't work. What could this be?

推荐答案

更新Xamarin.Forms版本后，该错误消失了！

After I updated my Xamarin.Forms version, the bug now is gone!

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