About long time ago, I already wrote about basic of BackgroundWorker component, BackgroundWorker Part 1.
It contained simple example on how to use BackgroundWorker and also ProgressBar. If you want to look then go to this url
This part 2 will go for more advance implementation example. This means application itself is simple but its coding technique is more advance.
As you may know by now that BackgroundWorker makes procedure run asynchronously. For example I have a procedure to run and the progress change of running procedure is reported.
This is possible because of this procedure run asynchronously by BackgroundWorker.
In order to run a BackgroundWorker, we have to use DoWork event handler function. So we need to write a procedure we want inside that DoWork function.
Most of examples show how to just write a whole codes in DoWork. For example below code:
void backgroundworker1_DoWork(object sender, DoWorkEventArgs e)
for (int i = 1; i <= numericUpDown1.Value; i++)
e.Cancel = true;
So it shows simple looping and send its report progress but the whole iteration coding is inside DoWork. When more complex requirement is needed then the coding become cumbersome.
We need a way to separate main procedure from DoWork function. So, it will also make loose coupling.
This procedure inside DoWork must have asynchronous capability. To accomplish this, I use Thread object. Thread will make asynchronous process.
Filling data to DataGridView with SqlDataAdapter is a common task but to cancel it in the middle of fill process need a tricky way. Especially when SqlDataAdapter returning large DataSet then no progress status informed to user since SqlDataAdapter need time to fetch DataSet. Also this project does not need to have button like “More records” to fetch more dataset. We can retrieve as much records you like and cancel it any time.
We need to show records immediately and user can cancel the retrieval process whenever they like. The basic idea is using int recordcount = SqlDataAdapter.Fill(int startrow, int maxrecords, DataTable dt) method at BackgroundWorker.DoWork event. That Fill method is similar to paging in web page. BackgroundWorker execute SqlDataAdapter.Fill in loop until it has no more record to fetch and we can cancel the process before or after SqlDataAdapter.Fill. Continue reading
Posted in C#
Tagged BackgroundWorker, C#, C# Example, DataGridView, dataset, DoWork, ProgressChanged, RunWorkerCompleted, SqlDataAdapter, Windows Form, WinForm
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