/// <summary>
///
/// </summary>
/// <param name="title">要顯示的標題文字。</param>
/// <param name="fieldName">對應資料庫或是 Value Object 的欄位名稱。</param>
public ListPaneFieldImproved(string title, string fieldName)
{
FieldName = fieldName;
CacheProvider = null;
CurrentCache = null;
if (Backend == null)
{
Backend = new QueryHelper();
}
Field = new ListPaneField(title);
Field.CompareValue += (CompareValue);
Field.PreloadVariable += (Field_PreloadVariable);
Field.GetVariable += (Field_GetVariable);
UISyncContext = TaskScheduler.FromCurrentSynchronizationContext();
}
private void Field_PreloadVariable(object sender, PreloadVariableEventArgs e)
{
if (IsDataLoading)
{
IsPaddingTask = true;
return;
}
if (IsReloading)
{
return;
}
if (CacheProvider != null)
{
CurrentCache = CacheProvider;
}
else
{
CurrentCache = new DynamicCache();
}
IsDataLoading = true;
Task task = Task.Factory.StartNew(() =>
{
if (CurrentCache.GetOutOfDate(e.Keys, FieldName))
{//如果不是在最新狀態就呼叫 GetDataAsync 讀取資料，並更新到 Cache 中。
if (e.Keys.Count() <= 0)
{
return; //如果沒有資料就不執行。
}
IEnumerable <Value> values = GetDataAsync(e.Keys);
HashSet <string> resultSet = new HashSet <string>();
foreach (Value v in values)
{
CurrentCache.FillProperty(v.Id, FieldName, v.Val);
resultSet.Add(v.Id);
}
HashSet <string> clearSet = new HashSet <string>(e.Keys);
clearSet.ExceptWith(resultSet);
//將沒有回傳的 Id 值清空。
foreach (string id in clearSet)
{
CurrentCache.FillProperty(id, FieldName, string.Empty);
}
}
}, new CancellationToken(), TaskCreationOptions.PreferFairness, TaskScheduler.Default);
task.ContinueWith((x) =>
{
IsDataLoading = false;
if (IsPaddingTask)
{
IsPaddingTask = false;
Field.Reload();
return;
}
if (x.Exception != null)
{
RTOut.WriteError(x.Exception);
}
else
{
IsReloading = true;
Field.Reload();
IsReloading = false;
}
CurrentCache = null;
}, UISyncContext);
}