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POentity framework cancel long running query
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  1. POentity framework cancel long running query
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    copied!<p>I am new to the TPL. I am using the TPL to make some async calls to the database. Below the GetDocumentAsync method is called multiple times and do a good job at offloading the task on a different thread to keep the UI thread responsive. </p> <p>There are two objectives here: 1) Keep the UI Thread Responsive 2) Give the user the ability to abort the request. </p> <p>I have managed to abort the request however i am unable to abort the request that Entity framework has already put to the database and the query is running at the db level.. or perhaps it has not even started. </p> <p>Therefore the GetDocuments method still returns the documents on the canceled tasks. </p> <p>Is there a away i can abort the request from the EF?? Can i do anything better in my implementation ?? </p> <pre><code> Entities _context = new Entities(); CancellationTokenSource _tokenSource = new CancellationTokenSource(); public async void GetDocumentsAsync(string userName) { IList&lt;Document&gt; results; try { results = await Task&lt;List&lt;Document&gt;&gt;.Factory.StartNew(() =&gt; { _tokenSource.Token.ThrowIfCancellationRequested(); return GetDocuments(userName); }, _tokenSource); } catch (OperationCanceledException ex) { Debug.WriteLine(string.Format("Task canceled for user {0} on thread", userName )); } if(!_tokenSource.IsCancellationRequested) { // results is used to update the UI } } public void Abort() { _tokenSource.Cancel(); } public List&lt;Document&gt; GetDocuments(string userName) { //I am using the connected model and need to use the Context for change tracking and other goodies.. var query = from c in _context.Documents where c.CreatedBy == userName select c; query = query.Take(50); // I want to be able to cancel this query. Can this be done ??? return query.ToList(); } </code></pre>
 

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