使用Blazor ClientSide应用程序实现事件订阅

我有我的服务界面(为简洁起见，已简化)； 公共接口INotificationService{事件动作OnChange;任务< ServiceResponse<通知>AddNotificationAsync(Notification notification);} ，在我的实现中，我调用 OnChange 事件(为简便起见再次降低)； 公共异步任务< ServiceResponse<通知>>AddNotificationAsync(通知通知){/*...*/StateChanged();} StateChanged()在哪里； 公共事件Action OnChange;private void StateChanged()=>OnChange?.Invoke(); 在我的 Blazor.Client 中，我按如下方法在 ConfigureServices 中解决了 INotificationService ； services.AddScoped< INotificationService，NotificationService>(); 然后我将服务注入到我要预订 OnChange()事件的组件中； @inject INotificationService NotificationService受保护的重写异步任务OnInitializedAsync(){NotificationService.OnChange + = StateHasChanged;} 然后在我的其他 razor 页面中，我再次注入相同的服务并调用 AddNotificationAsync 方法； @inject INotificationService NotificationService等待NotificationService.AddNotificationAsync(新通知{级别= NotificationLevel.Success，Text = $已成功添加ID = {agreementType.Id}的协议类型.".ToString()}); 但是，调用t NotificationService.AddNotificationAsync 不会触发组件的 OnChange 和 StateHasChanged ，因为该组件未刷新?有什么想法请问我在这里做错了吗?解决方案以下Microsoft文档从外部调用组件方法以更新状态，您应该更改: @inject INotificationService NotificationService受保护的重写异步任务OnInitializedAsync(){NotificationService.OnChange + = StateHasChanged;} 通过: @inject INotificationService NotificationService受保护的重写异步任务OnInitializedAsync(){NotificationService.OnChange + = OnNotify;}公共异步任务OnNotify(){等待InvokeAsync(()=>{StateHasChanged();});} 在您的代码中，您正在Blazor的SynchronizationContext之外调用组件的 StateHasChanged 方法. InvokeAsync用于切换到正确的上下文并使渲染排队.Our Blazor App is running on preview9.I am trying to implement a .razor component that listens to an event from a NotificationService we have written to refresh the view whenever the service is invoked, but I seem to be missing something;I have my service Interface (reduced for brevity);public interface INotificationService{ event Action OnChange; Task<ServiceResponse<Notification>> AddNotificationAsync(Notification notification);}and in my implementation I invoke the OnChange event (again reduced for brevity);public async Task<ServiceResponse<Notification>> AddNotificationAsync(Notification notification){ /*...*/ StateChanged();}Where StateChanged() is;public event Action OnChange;private void StateChanged() => OnChange?.Invoke();In my Blazor.Client I resolved INotificationService in ConfigureServices as follows;services.AddScoped<INotificationService, NotificationService>();I then inject the service into the component I want to subscribe to the OnChange() event; @inject INotificationService NotificationService protected override async Task OnInitializedAsync() { NotificationService.OnChange += StateHasChanged; }And then in my other razor page I again inject the same service and call the AddNotificationAsync method;@inject INotificationService NotificationService await NotificationService.AddNotificationAsync( new Notification { Level = NotificationLevel.Success, Text = $"Agreement Type with Id = {agreementType.Id} has been successfully added.".ToString() });However, calling t NotificationService.AddNotificationAsync is not triggering the OnChange and then the StateHasChanged of the component, as the component is not refreshing? Any ideas what I am doing wrong here please? 解决方案 Following Microsoft docs Invoke component methods externally to update state, you should to change: @inject INotificationService NotificationService protected override async Task OnInitializedAsync() { NotificationService.OnChange += StateHasChanged; }By: @inject INotificationService NotificationService protected override async Task OnInitializedAsync() { NotificationService.OnChange += OnNotify; } public async Task OnNotify() { await InvokeAsync(() => { StateHasChanged(); }); }In your code, you are invoking the component's StateHasChanged method outside of Blazor's SynchronizationContext. InvokeAsync is used to switch to the correct context and queue a render. 这篇关于使用Blazor ClientSide应用程序实现事件订阅的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！