C# DataSource ExampleUse the DataSource property in Windows Forms. With this property, the code updates elements in a ListBox.
DataSource. The DataSource property allows data binding on Windows Forms controls. With it we bind an array to a ListBox on the screen—and display all the strings. As changes are made to the List, we update the control on the screen.
Example. Your ListBox control—or any different kind of control you may have—has a DataSource property that can be assigned a value. You can assign a collection to it. Collections include arrays, Lists and DataTables.
MainWindow This Form has a member variable of the List generic type. This will be where we want to store the strings that will show on the ListBox.
Note The constructor and the partial class and InitializeComponent were autogenerated by the Designer.
Constructor The code assigns to the DataSource. The DataSource property is assigned to the List member variable.
Example 2. The point here is that we want to add items to the ListBox. We can add items to the bottom or the top, or anywhere in between. A good effect is adding items to the top, so they are easily seen.
Next Here is a custom method that prepends a string to the top of the control, and then makes it display.
List Insert
String The method receives a string and then Inserts it to the start of the member List, and then forces the ListBox to refresh.
Cast The syntax at the end does a cast and a lookup to get the CurrencyManager and then Refreshes the ListBox.
Tip In the CurrencyManager type, the word Currency refers to current. It is used to ensure a control is current.
Example that sets DataSource property, C#:
public partial class MainWindow : Form { List<string> _sideList = new List<string>(); public MainWindow() { InitializeComponent(); sideListBox1.DataSource = _sideList; } }
Example 3. So far we have seen the DataSource assignment and then the method AddListLine that inserts a string at the top of the ListBox. This setup allows us to send a string to the method. It will show up at the top of the ListBox.
Example that uses BindingContext, C#:
private void AddListLine(string lineIn) { // ... Insert the string at the front of the List. _sideList.Insert(0, lineIn); // ... Force a refresh of the ListBox. ((CurrencyManager)sideListBox1.BindingContext[_sideList]).Refresh(); }
Summary. We used the DataSource property on a ListBox control in Windows Forms. By combining one List, DataSource and ListBox, and using CurrencyManager, we have a ListBox that will show the newest result on the top.
Thus These properties together result in an interface that is versatile and easily maintained.
Example that calls method, C#:
void backgroundWorker1_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e) { // ... Show some results from the BackgroundWorker task. AddListLine("5000 games: " + (string)e.Result); }
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