主线程尝试访问尚未由后台线程填充的数据

Question

I have a UI which takes 10-15 seconds to load. So implemented Background thread (BG Thread) to load data. As BG Thread gets data, main thread starts to execute remainder of the code and this is where problem starts..ie

When step 1 below, is executed by BG Thread only... main thread tries to execute step 2

How do I make sure that until I get records from background thread (Step 1), step 2 is not executed?

So, here are the steps that gets executes..

===========This piece is executed only by BG Thread===============================================
Step 1. Get data from DB
   new Thread(() => 
   {
    Thread.CurrentThread.IsBackground = true; 
    My DB call goes here... and populates productCollection used in step 2 below
   }).Start();

==========================================================

Step 2.
if(productCollection?.Count > 0)  // This collection is always 0 becuase BG Thread (step 1) has not yet populated the collection and user get "No record message"
{

  // Filter collection based on some criteria
  // assign the filtered collection to datagrid
  dgProducts.DataSource = productCollection;      
}
else
{
 // show message to user that "No records found for given criteria";
}

Answer 1

You should be able to do it like this with a task.

 public partial class MainWindow : Window
{
    public MainWindow()
    {
        InitializeComponent();
        SetDataSource();
    }

    public async void SetDataSource()
    {
        dgProducts.DataSource = await Task.Run(() =>
        {
            //My DB call goes here... and populates productCollection used in step 2 below
            return productCollection;
        });
    }
}

On the other hand if you were wrong and the query just really takes 10-15 seconds this will not help you. Then you should be looking into how to speed up your DB Calls inside of your DB.