这个错误是由于Blazor组件在渲染时尝试添加addEventListener时引发的,但是该组件尚未完全加载并存在于DOM中,因此无法添加事件侦听器。为了解决这个问题,您可以在组件加载后才添加事件侦听器。以下是示例代码:
public class EventComponent : ComponentBase, IDisposable
{
private readonly Dictionary> _eventCallbacks = new ();
protected void AddEventListener(string eventName, EventCallback eventCallback)
{
if (_eventCallbacks.ContainsKey(eventName))
{
_eventCallbacks[eventName] = eventCallback;
}
else
{
_eventCallbacks.Add(eventName, eventCallback);
}
if (IsEventTargetReady())
{
AddEventListenerImpl(eventName);
}
}
protected void RemoveEventListener(string eventName)
{
_eventCallbacks.Remove(eventName);
RemoveEventListenerImpl(eventName);
}
protected virtual void AddEventListenerImpl(string eventName)
{
// Implement the event listener attach logic in a derived class
}
protected virtual void RemoveEventListenerImpl(string eventName)
{
// Implement the event listener remove logic in a derived class
}
protected virtual bool IsEventTargetReady()
{
// Implement the check if the event target is ready in a derived class
return true;
}
protected void RaiseEvent(string eventName, EventArgs args)
{
if (_eventCallbacks.TryGetValue(eventName, out var callback))
{
callback.InvokeAsync(args);
}
}
public void Dispose()
{
foreach (var eventName in _eventCallbacks.Keys)
{
RemoveEventListenerImpl(eventName);
}
}
}
public class MyComponent : EventComponent
{
private ElementReference _elementRef;
protected override void AddEventListenerImpl(string eventName)
{
_elementRef.Value?.AddEventListener(eventName, CreateEventCallback(eventName));
}
protected override void RemoveEventListenerImpl(string eventName)
{
_elementRef.Value?.RemoveEventListener(eventName, CreateEventCallback(eventName));
}
protected override bool IsEventTargetReady()
{
return _elementRef.Id != null;
}
private EventCallback CreateEventCallback(string eventName)
{
return EventCallback.Factory.Create(this, args =>
{
RaiseEvent(eventName, args);
});
}
}