Task, AsyncAction, CatchHandling, 把同步的 Action 叫用轉換成非同步的 Action 叫用。

AsyncAction.cs

/// ref→[Converting Action method call to async Action method call](https://stackoverflow.com/questions/33941583/converting-action-method-call-to-async-action-method-call)
/// 把同步的 Action 叫用轉換成非同步的 Action 叫用。
/// Action ==> async Action

Execute(()=> { do_some_thing });

轉換成：即 Action ==> 非同步化 ==> Task<Func>

ExecuteAsync(async ()=> { do_some_thing_async });

//=================================
//## 同步的 Action 叫用語法
void Execute(Action action)
{
    try
    {
        action();
    }
    finally
    {
    }
}

===> 轉換成
//## 非同步的 Action 叫用語法
// 需把 Action 換成 Func<Task> 就可以 await 了

async Task ExecuteAsync(Func<Task> func)
{
    try
    {
        await func();
    }
    finally
    {
    }
}

AsyncAction_apply.cs

List<TodoDto> dataList = new();
bool f_testFail = false;
string newTodoDesc = string.Empty;
bool f_loading = false;
string errMsg = string.Empty;

//protected override async Task OnInitializedAsync()
//{
//  await base.OnInitializedAsync();
//  await HandleQuery();
//}

Task HandleQuery() => CatchHandling(async () =>
{
  await Task.Delay(500);

  var qryArgs = new TodoQryAgs
    {
      Msg = f_testFail ? "測試邏輯失敗" : "今天天氣真好",
      Amt = 999
    };

  dataList = await bizApi.QryDataListAsync(qryArgs);
});

Task HandleAdd() => CatchHandling(async () =>
{
  var newTodo = await bizApi.AddFormDataAsync(newTodoDesc);

  // Success
  dataList.Add(newTodo);
  newTodoDesc = string.Empty;
});

//# AOP with Decorator
async Task CatchHandling(Func<Task> action)
{
  try
  {
    f_loading = true;
    errMsg = string.Empty;
    await action();
  }
  catch (ApiException ex)
  {
    if (ex.StatusCode == HttpStatusCode.BadRequest)
    {
      var msg = await ex.GetContentAsAsync<ErrMsg>();
      errMsg = $"ApiException: {msg.Severity}-{msg.Message}";
    }
    else
    {
      errMsg = $"ApiException: {ex.Message}";
    }
  }
  catch (Exception ex)
  {
    errMsg = "EXCEPTION: " + ex.Message;
  }
  finally
  {
    f_loading = false;
  }
}

CatchHandling.cs

// 在同步語法的宣告：
void CatchHandling(Action action) {}

// 轉換成非同步就變成如下：
// 即 Action ==> 非同步化 ==> Task<Func>
async Task CatchHandling(Func<Task> action)
{
  try
  {
    f_loading = true;
    errMsg = string.Empty;
    
    // 執行
    await action();
  }
  catch (ApiException ex)
  {
    if (ex.StatusCode == HttpStatusCode.BadRequest)
    {
      var msg = await ex.GetContentAsAsync<ErrMsg>();
      errMsg = $"ApiException: {msg.Severity}-{msg.Message}";
    }
    else
    {
      errMsg = $"ApiException: {ex.Message}";
    }
  }
  catch (Exception ex)
  {
    errMsg = "EXCEPTION: " + ex.Message;
  }
  finally
  {
    f_loading = false;
  }
}