public override void Load(IEntityCollectionView <T> view)
{
lock (TimerLock)
{
if (Timer == null)
{
Timer = new DispatcherTimer();
Timer.Tick += (s, arg) =>
{
lock (TimerLock)
{
if (Timer != null)
{
Timer.Stop();
Timer = null;
LoadData(view);
}
}
};
Timer.Interval = RequestDelay;
Timer.Start();
}
}
}
public abstract void Load(IEntityCollectionView <T> view);
private void LoadData(IEntityCollectionView <T> view)
{
#region query
var requestId = ++RequestId;
var query = Queryable.IncludeTotalCount();
#endregion query
#region paging
if (view.PageSize > 0)
{
query = query
.Skip(view.PageIndex * view.PageSize)
.Take(view.PageSize);
}
#endregion pagging
#region filters
foreach (var filterExpression in view.FilterExpressions)
{
var remoteExpression = DataServiceQueryable.ToRemoteExpression(filterExpression);
query = query.Where(remoteExpression);
}
#endregion filters
#region sorting
// apply sort descriptors
IOrderedDataServiceQueryable <T, T> sortedQuery = null;
foreach (var sortDescription in view.SortDescriptions)
{
var sortExpression = sortDescription.ToExpression <T>();
if (ReferenceEquals(sortedQuery, null))
{
sortedQuery = query.OrderBy(sortExpression);
}
else
{
sortedQuery = sortedQuery.ThenBy(sortExpression);
}
}
if (!ReferenceEquals(sortedQuery, null))
{
query = sortedQuery;
}
#endregion sorting
#region request
// notify data loading
OnDataLoading();
query.ExecuteAsync(
(result) =>
{
if (requestId < RequestId)
{
// request outdated
return;
}
// synchronize with main thread
Dispatcher.BeginInvoke((Action) delegate
{
// check for exception
if (result.IsFaulted)
{
var queryException = QueryException;
if (queryException != null)
{
queryException(this, new ExceptionEventArgs(result.Exception));
OnDataLoaded(null);
return;
}
else
{
throw new Exception("Query failed", result.Exception);
}
}
// retrieve data
var entitySet = result.EntitySet;
// fill items
view.Clear();
foreach (var item in entitySet)
{
view.Add(item);
}
// sets total count
view.TotalItemCount = entitySet.TotalCount.HasValue ? (int)entitySet.TotalCount.Value : -1;
// notify data loaded
OnDataLoaded(entitySet);
});
}
);
#endregion request
}
