列表视图中列出的选定组合框项目

Question

I want to list selected combo box items in a listView by using LINQ to SQL. With my understanding the coding I have should work but it doesnt.(This coding should only display the CB items in the listview)

string pname = cbItem.SelectedItem.ToString();
listview.ItemsSource = DC.tblProducts.Where(p => p.ProductName == pname);

I basically want to make like a shopping cart but only to display the items that are selected thank you.

Answer 1

I think that your problem lies here:

listview.ItemsSource = DC.tblProducts.Where(p => p.ProductName == pname);

From Microsoft's documentation on Enumerable.Where, emphasis mine ( https://msdn.microsoft.com/en-us/library/vstudio/bb534803%28v=vs.100%29.aspx ):

This method is implemented by using deferred execution. The immediate return value is an object that stores all the information that is required to perform the action. The query represented by this method is not executed until the object is enumerated either by calling its GetEnumerator method directly or by using foreach in Visual C# or For Each in Visual Basic.

The LINQ statement has been defined but not evaluated, and as such doesn't have a value that ItemsSource can figure out. Try:

string pname = cbItem.SelectedItem.ToString();
var result = DC.tblProducts.Where(p => p.ProductName == pname);

var myList = new List<TblProductType>();
foreach(var v in result)
{
    myList.Add(v);
}
listview.ItemsSource = myList;