Blazor組件通信StateContainer呼叫不起作用-有解無憂

我有一個 AppState 服務，它具有以下內容：

public event Action OnDataChanged;
public MyObject CurrentObject { get; private set; }

public void UpdateMyObject(MyObject obj)
        {
            CurrentObject = obj;
            OnDataChanged?.Invoke();
        }

在一個組件中，我呼叫UpdateMyObject. 該AppState服務確實受到正確資料的影響，并被OnDataChanged?.Invoke()呼叫。

在另一個應該訂閱以OnDataChanged對資料更新做出決定的組件中，我有以下內容：

protected override void OnInitialized()
    {
        AppStateService.OnDataChanged = UpdateData;
    }

 private void UpdateData()
    {
        var data = AppStateService.CurrentObject;
    }

我試圖在“監聽”組件上放置斷點，但沒有任何結果。關于我做錯了什么以及為什么不從狀態服務UpdateData呼叫方法的任何想法？OnChanged?.Invoke關于如何除錯的建議？

uj5u.com熱心網友回復：

這是我的有效代碼 - 我在 Blazor Server 模板解決方案中構建了它。為簡單起見，我已將您的物件設為字串。

public class AppState
{
    public Guid Id { get; } = Guid.NewGuid();

    public event Action? OnDataChanged;

    // This is more normal for events
    public event EventHandler? DataChanged;

    public string? CurrentObject { get; private set; }

    public void UpdateMyObject(string obj)
    {
        CurrentObject = obj;
        OnDataChanged?.Invoke();
        DataChanged?.Invoke(this, new EventArgs());
    }
}

服務注冊

builder.Services.AddSingleton<WeatherForecastService>();
// Set as a singleton as the name suggests it's application specific and not user specific
builder.Services.AddSingleton<AppState>();

顯示狀態的組件

// AppStateComponent.razor
@inject AppState AppStateService
@implements IDisposable
<h3>AppStateComponent</h3>

<div class="m-2 p-2">
    Service ID: @this.AppStateService.Id.ToString()
</div>

<div>
    Data: @this.data
</div>
@code {

    private string data = string.Empty;

    protected override void OnInitialized()
    {
        this.AppStateService.OnDataChanged  = UpdateData;
    }

    private void UpdateData()
    {
        data = this.AppStateService.CurrentObject!;
        this.InvokeAsync(StateHasChanged);
    }

    public void Dispose()
    {
        this.AppStateService.OnDataChanged -= UpdateData;
    }
}

和一個測驗頁

@page "/"
@inject AppState AppStateService
<div class="m-2 p-2">
    Service ID: @this.AppStateService.Id.ToString()
</div>

<AppStateComponent />

<div class="m-2">
    <button class="btn btn-dark" @onclick=UpdateData>Update</button>
</div>

@code {

    private void UpdateData()
    {
        this.AppStateService.UpdateMyObject($"Updated at {DateTime.Now.ToLongTimeString()}");
    }
}

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標籤：。网西装外套 blazor 服务器端

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