Question

I have a form that is loading quite an amount of data from SQL server. Below is the code that will provide a good hint:

private void BranchCenter_Load(object sender, EventArgs e) {
  //Combo boxes:
  LoadCities();
  LoadCoordinators();
  LoadComputerSystems();

  //Actual entity
  LoadBranch();
}

private void LoadCities() {
  //LINQ2SQL to load data. ~5000 records.
}

private void LoadCoordinators() {
  //LINQ2SQL to load data. ~50 records.
}

private void LoadComputerSystems() {
  //LINQ2SQL to load data. ~550 records.
}

private void LoadBranch() {
  LoadBranchInit();
  LoadBranchDetails();
  LoadBranchTimings();
  LoadBranchServices();
  LoadBranchLocumsHistory();
  LoadBranchJobs();
  LoadBranchNotes();
}

private void LoadBranchInit() {
  //LINQ2SQL to load the Branch object based upon the Branch ID
}

private void LoadBranchDetails() {
  //LINQ2SQL to load basic branch stuff. 38 fields. Mixed editors.
}

private void LoadBranchTimings() {
  //LINQ2SQL to load timings info into 80 date-time controls
}

private void LoadBranchServices() {
  //LINQ2SQL to load services offered at branch info into 20 check-boxes controls
}

private void LoadBranchLocumsHistory() {
  //LINQ2SQL to load branch history info into grid control. Always increasing # of rows :(
}

private void LoadBranchJobs() {
  //LINQ2SQL to load branch jobs info into grid control. Always increasing # of rows :( 
}

private void LoadBranchNotes() {
  //LINQ2SQL to load branch notes info into grid control
}

The UI is a form with a tab controls. each detail from above goes to a tab page. I need to load and show the form to user as fast as possible. once the form is shown, i need to launch a series of background workers to get the data for each page.

I have been trying to mess with the background worker but unable to understand it’s usage. I end up getting message of “different thread attempted to access control on your main thread… or something like that…”

The ideal situation would be to have a progress bar loading the data on every tab and the tab becoming inter-actable once the respective background worker finishes.

Any strategy or advice? Thanks for the read.

Answer 1

Create a BackgroundWorker for each of the tabs. In the Load event of the form, disable all tabs and call the RunWorkerAsync() method for each of the background workers.

In each DoWork event handler, load the data required for the associated tab page from the database into a data table and set the Result property of the DoWorkEventArgs to the data table.

Note: In the DoWork event handler you should NOT update any UI control since it is operating in a different thread. You should only retrieve the data from the database and set the Result property.

In the RunWorkerCompleted event handlers, you can access the data table, that was retrieved in the DoWork event handler, by getting the Result property of the RunWorkerCompletedEventArgs. Then you can set the properties of the UI controls accordingly and then enable the tab page associated with the current background worker.