将多个项目/对象添加到ListBox

Question

I have 3 Dropdown Lists (could be more in future).

DropdownList1 is a parent and is populated from a database.
DropdownList2 is a child and is populated from the selected item from DropdownList1.
DropdownList3 is a child and is populated from the selected item from DropdownList2.

I would like to add the selected item to a ListBox.

The problem i have is DropdownList2 and DropdownList3 may not always have a child item, so to add the items to a ListBox, i could store their IDs but display their text.

My database table has 3 columns to save the value (ID) from the 3 dropdown lists.

My question is if i display the text of the item in the ListBox, the next step is to save the data into the table into the relevant columns (so column 1 would save data from DD1, Column 2 would save from DD2 etc) is there anyway to identify which ID the item belongs to, so i can save the correct ID to the correct column?

So a user selects item 1 from DD1 item 2 from DD2, there is no item available from DD3, so they click add which adds the item to the ListBox. When i have to save this item how could i distinguish the item added was upto DD2 therefore it needs to be added to Column2? Or is there a better approach?

Hope this makes sense

Answer 1

List boxes don't like to store multiple values. They can, however, store objects as their datasource.

First create a custom object, then assign the values from each of your dropdown lists to the object:

Declare a new list of your custom object first

List<myObject> list = new List<myObject>();

then assign this to your button:

private void Button1_Click(object sender, EventArgs e)
{

    myObject object = new myObject(Dropdown1, Dropdown2, Dropdown3);
    list.Add(object);

    //assign the list to the Listbox control
    ListBox.Datasource = list;

}

When you want to access the values for your query, use a foreach loop to cycle over the objects in the list, with a pointer value to access each of them.

foreach (myObject obj in list)
{
    var val1 = list[obj].Dropdown1;
    var val2 = list[obj].Dropdown2;
    var val3 = list[obj].Dropdown3;

    //enter your sql code here
}

Let me know if you want to expand further.