VB.NET - Accessing A Dataset From Within A Threaded Class Instance? - vb.net

Question

I was using the following code within a class and creating an instance of that class from within my main form (Main.vb):
Dim count As Integer = Main.DbDataSet.Accounts.Count
This was returning the count of accounts within my database.
After changing the code so that I could run this in a background thread to save locking up the program, as more data is processed after this point, the count was returning 0 each time.
Is it possible to access my DbDataSet within a threaded process (Another class)?

Answer 1

From your description, I presume you have to read more on threading. This is to ensure that you are aware that you are playing with a double edged blade (Threading). There are few good material which you can find in net. Namely threading in C#.
Now, with the limited knowledge on what you are trying to do at your end; following code plot a blue print on how the code should look like.
class YourForm
{
private DataSet dataSet;
public int Count { get; set; }
SynchronizationContext runningContext;
public YourForm()
{
}
void FillData()
{
//fill your dataset with required data
}
void ProcessInWorker()
{
runningContext=SynchronizationContext.Current;
Two secondClass = new Two();
secondClass.DoWork +=secondClass_DoWork;
secondClass.RunWorkerCompleted +=secondClass_RunWorkerCompleted;
YourRequest re=new YourRequest()
{
DatasetToSend=dataSet
}
secondClass.RunWorkerAsync(re);
}
void secondClass_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
if (e.Error != null) throw e.Error;
YourResponse cResponse = e.Result as YourResponse;
if (cResponse == null) return;
dataSet = cResponse.RefilledData;//latest data will be here on completion of worker thread.
//if you want you can update latest count in some UI control say txtRecordCount
runningContext.Post(new SendOrPostCallback(delegate
{
txtRecordCount.Text=//give your row count here;
}), null);
}
void secondClass_DoWork(object sender, DoWorkEventArgs e)
{
try
{
YourRequest cRequest = e.Argument as YourRequest;
cRequest.DatasetToSend = RefillData();
YourResponse cResponse=new YourResponse()
{
RefilledData=cRequest.DatasetToSend
};
e.Result = cResponse;
}
catch
{
throw
}
}
DataSet RefillData()
{
//put your logic here to refill the data in dataset
//return the dataset;
}
}
class Two : BackgroundWorker
{
//sub classing background worker and rest of your own
//logic which you are planning for second class.
}
class YourRequest
{
public YourRequest ()
{
}
public DataSet DatasetToSend{get;set;}
}
class YourResponse
{
public YourResponse()
{
}
public DataSet RefilledData { get; set; }
}