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POHow To: Best way to run a threaded loop with a UI update at the end of each?
 

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  1. POHow To: Best way to run a threaded loop with a UI update at the end of each?
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    <p>an architectural question here.</p> <p>I have a List (selected via a listview) that needs to be sent to a webservice and created in the database. I want to be able to update one at a time then update a progress bar, listview and local List with the returned ID without locking up the uithread (although i'll have lock the listview/search controls etc they just need to be able to complete other task in different forms).</p> <p>At the minute i've considered the following (new to most)</p> <p>Background worker - the only problem here is that the progressChanged only returns an int so i'd find it difficult to return all the information I need.</p> <p>Tasks - i'm using these at the minute when all I need to return a single object and then process that information (like getting list from local database and then populating listview and that works well). I can't figure out how to spawn a thread that in turn does a loop and updates the UI Thread at the end of each pass.</p> <p>parallel.foreach - don't think this would be suitable with the web services element.</p> <p>All the stuff i've tried so far, either locks the UI or gets cross thread exceptions.</p> <p>I guess i'm looking for something that allows me to do this</p> <pre><code>createUsers(ref List&lt;users&gt; _users) { foreach(user _u in _users) { //call webservice and update - it returns an ID or null string newID = webCreate(_u); if (newID != null) { ListViewItem lvi = listview1.FindText(_u.ListID); lvi.SubItems[5].Text = newID; _u.newID = newID; } else { lvi.SubItems[5].Text = "Error"; } progressbar.value++ } } </code></pre> <p>There just seems to be so many options in .net 4.0 for threading I just can't think which one will best serve me. Any pointers would be great. </p> <p>Thanks, Pete.</p>
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    1. USPeter Lea
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    1. COJust as an aside, why are you using `ref` here, when you're never assigning a new value to `_users`?
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      1. POHow To: Best way to run a threaded loop with a UI update at the end of each?
      1. USJon Skeet
    2. COI update the value here _u.newID = newID;
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      1. POHow To: Best way to run a threaded loop with a UI update at the end of each?
      1. USPeter Lea
    3. COCall the BackgroundWorker.ReportProgress(Int32, Object) and pass the information (an instance of a class) as the object parameter. At the BackgroundWorker.ProgressChanged event hook, check for the ProgressChangedEventArgs parameter, which will contain the UserState property with the class you passed.
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      1. POHow To: Best way to run a threaded loop with a UI update at the end of each?
      1. USJoanComasFdz
 

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