WinUI3 TemplateStudio使用ILocalSettingsService读本地设置遇空引用异常

核心原因 #

空引用异常源于_settingsService未被正确初始化——TemplateStudio依赖注入框架要求通过构造函数注入ILocalSettingsService实例，若页面未在构造函数中接收并赋值该实例，会导致_settingsService为null。

修复步骤 #

1. 通过构造函数注入服务 #

修改页面类的构造函数，添加ILocalSettingsService参数并赋值给私有字段：

using Microsoft.TemplateStudio.UI.Services;

private readonly ILocalSettingsService _settingsService;

// 替换YourPage为你的页面类名
public YourPage(ILocalSettingsService settingsService)
{
    InitializeComponent();
    _settingsService = settingsService;
}

2. 修正异步方法调用逻辑 #

ReadSettingAsync是异步方法，直接使用.Result易引发UI线程死锁，改用async/await调用：

private async void Page_Loaded(object sender, Microsoft.UI.Xaml.RoutedEventArgs e)
{
    // 注意：原代码键名拼写错误——notifiacations → notifications
    var notifications = await _settingsService.ReadSettingAsync<string>("notifications");
    var notificationsSound = await _settingsService.ReadSettingAsync<string>("notifications.sound");

    NotificationToggle.IsOn = notifications == "on";
    NotificationSoundToggle.IsOn = notificationsSound == "on";
}

3. 修正键名拼写错误 #

原代码中第一个设置键名写成notifiacations（缺失字母t），会导致无法读取正确配置，需修正为notifications。

内容的提问来源于stack exchange，提问作者Luis