CODEWITHSUNDEEP
c#taskcontinuewith
user9641573
user9641573

Reputation:

ContinueWith change my list order

I have a list of information Each of these information must be in a user control, It takes a long time to create a user control And the user interface hangs so i used Task.Delay.ContinuWith () (In order to update the user interface after adding any item)
But there is a problem, Information is not displayed in sequence

Dispatcher.Invoke(new Action(() =>
            {
                waterfallFlow.Children.Clear();
                    var parsedValues = doc.DocumentNode.SelectNodes(...).Skip(1)
                         .Select(r =>
                         {...}).ToList();
                    foreach (var item in parsedValues)
                    {
                        Task.Delay(200).ContinueWith(ctx =>
                        {
                            waterfallFlow.Children.Add(_currentUser);
                            waterfallFlow.Refresh();
                        }, TaskScheduler.FromCurrentSynchronizationContext());
                    }
                }
            }), DispatcherPriority.ContextIdle, null);

Output is:

ID | Name |

10 | Ali
9 | Hadi
1 | Hasan
15 | kajsd
...
But the information should be received as follows

ID | Name |

1 | Hasan
2 | ad
2 | ad
3 | ad
...

Upvotes: 0

Views: 59

Answers (1)

Nkosi
Nkosi

Reputation: 247018

Consider using the Dispatcher.Invoke<TResult> over load and simply awaiting a Task

Dispatcher.Invoke<Task>(async () => {
    waterfallFlow.Children.Clear();
    var parsedValues = doc.DocumentNode.SelectNodes(...)
        .Skip(1)
        .Select(r => {...})
        .ToList();
    foreach (var item in parsedValues) {
        await Task.Delay(200);
        waterfallFlow.Children.Add(item);
        waterfallFlow.Refresh();
    }
}, DispatcherPriority.ContextIdle, null);

this should allow the items to be added in the same order they were read.

Upvotes: 0

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