MAUI中Syncfusion Popup绑定独立ContentView数据失败求助

问题根源 #

你的MyView构造函数中设置了BindingContext = this，这会覆盖从父级（Popup的ContentTemplate）继承的BindingContext，导致ContentView内部的绑定无法关联到页面的ViewModel。原本Data="{Binding MyString}"是期望绑定到ViewModel的MyString，但因为BindingContext被改成了MyView自身，这个绑定会失效。

修复方案 #

1. 移除MyView构造函数中的BindingContext赋值

修改MyView.cs，删除BindingContext = this这一行：

namespace MinimalNotWorkingExample;

public partial class MyView : ContentView
{
    public static readonly BindableProperty DataProperty =
    BindableProperty.Create("Data", typeof(string), typeof(MyView));
    public string Data
    {
        get => (string)GetValue(DataProperty);
        set => SetValue(DataProperty, value);
    }
    public MyView()
    {
        InitializeComponent();
    }
}

2. 修改MyView.xaml中的绑定路径

由于ContentView现在继承父级的BindingContext（即ViewModel），内部Label需要通过RelativeSource指定绑定源为ContentView本身，才能正确访问Data属性：

<?xml version="1.0" encoding="utf-8" ?>
<ContentView xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             xmlns:local="clr-namespace:MinimalNotWorkingExample"
             x:Class="MinimalNotWorkingExample.MyView">
    <VerticalStackLayout>
        <Label 
            Text="If you can Read this, the ContentView was loaded. IF you can see the same text below as in the header, the Binding is working."
            VerticalOptions="Center" 
            HorizontalOptions="Center"
            TextColor="Black"/>
        <Label 
            Text="{Binding Data, Source={RelativeSource AncestorType={x:Type local:MyView}}}"
            VerticalOptions="Center" 
            HorizontalOptions="Center"
            TextColor="Black"/>
    </VerticalStackLayout>
</ContentView>

验证效果

修改后，点击第一个按钮弹出使用ContentView的弹窗时，Label的内容会正确绑定到ViewModel的MyString，和弹窗标题保持一致，绑定功能恢复正常。

内容的提问来源于stack exchange，提问作者Thorsten Schmitz