Blazor EventCallback with Multiple Params - how to respond to event in parent host control

Question

I have a blazor component with an EventCallBack parameter that utilized the new struct format allowing multiple arguments

[Parameter] public EventCallback<(EmployeeShiftDay, DateTime, DateTime)> NewDayScrolledIntoView { get; set; }

eventcallback is invoked in child normally as such

await NewDayScrolledIntoView.InvokeAsync(p1, p2, p3);

In my host page I have the corresponding method to handle the invoke

private void NewDayInView(EmployeeShiftDay dayInView, DateTime weekStart, DateTime weekEnd)
{
   ...
}

How do I add the markup for this EventCallBack in the host component - I need of course 3 params not just one

<ShiftCardScroller NewDayScrolledIntoView="@((args) => NewDayInView(args))" ></ShiftCardScroller>

Answer 1

您正在调用它解构：

await NewDayScrolledIntoView.InvokeAsync((p1, p2, p3));

当接收到事件时，解构它然后：

<ShiftCardScroller NewDayScrolledIntoView="@((args)=> NewDayInView(args.Item1,args.Item2,args.Item3))" />

Answer 2

您可以使用自定义参数类型，如下所示：

public class EventCallbackArgs
{
    public bool Confirm { get; set; }
    public Guid Id { get; set; }
    public string Name { get; set; }
}

这是 blazor 代码示例

<button type="button" class="btn btn-danger" @onclick="() => OnConfirmationChange(true)">
    Delete
</button>

单击“删除”按钮时，将调用OnConfirmationChange，在 OnConfirmationChange 的代码中，您可以准备EventCallbackArgs并调用ConfirmationChanged

[Parameter]
public EventCallback<EventCallbackArgs> ConfirmationChanged { get; set; }
public EventCallbackArgs args { get; set; }

protected async Task OnConfirmationChange(bool deleteCofirmed)
{
    ShowConfirmation = false;
    args = new EventCallbackArgs { Id = id, Name = name };
    args.Confirm = deleteCofirmed;
    await ConfirmationChanged.InvokeAsync(args);
}

Answer 3

对我来说@Brian Parker 的解决方案不起作用，需要稍作修改：

（相同的）

await NewDayScrolledIntoView.InvokeAsync((p1, p2, p3));

元组铸造：

<ShiftCardScroller NewDayScrolledIntoView="@((args)=> NewDayInView(((EmployeeShiftDay,DateTime,DateTime))args))" />

方法采用一个参数。类型与之前铸造的类型一致：

private void NewDayInView((EmployeeShiftDay,DateTime,DateTime)args)
{
   ...
}

有时需要重新启动 Visual Studio 才能消除不相关的错误消息。