C# databound ComboBox changing data in other controls

Question

Once again I have a very complicated question so I'll try and explain as well as I can:

I have a C# Windows Forms (.NET 4) program. My Windows Form contains one large blank panel.
Inside this program, I have a Windows Form UserControl class with a designer. The user control is a box with two ComboBoxes and a TextBox on it (call it a menu choice).

Each ComboBox on the user control is bound to a different DataSource using:

comboBoxSelection1.DataSource = SelectionList1;
comboBoxSelection2.DataSource = SelectionList2;

When the user selects an item using the ComboBoxes, the TextBox shows their choices.
Eg Selection 1: Steak, Selection 2: Chips.

The entire point of this program is to allow the user to create multiple user controls (menu choices) each with different selections, resulting in a list of selections (which becomes one single order).

With me so far?
This worked absolutely fine before I started using DataSource for the ComboBoxes, like so:

object[] comboBoxList1 = new object[SelectionList1.Count];
int i = 0;
foreach (Selection s in SelectionList1)
{
    string description = s.Description;
    comboBoxList1[i] = description;
    i++;
}
comboBoxSelection1.Items.AddRange(comboBoxList1);

However, I need to use a DataSource in order to differentiate items by id (some displayed names are identical - I cannot change this).

I am now using the following:

comboBoxSelection1.DataSource = SelectionList1;
comboBoxSelection1.ValueMember = "Code";
comboBoxSelection1.DisplayMember = "Name";

The problem is that whenever I change comboBoxSelection1 on one of my user controls, the comboBoxSelection1 value on every user control on the panel changes to my current selection. The same happens with comboBoxSelection2 if I change a value in any comboBoxSelection2, all comboBoxSelection2 boxes change to the same value.

Is this a bug with using one DataSource for multiple controls?
It has been seen here: Data Bound ComboBox: List item changed when I select another

In this case, the issue was solved by using DataBindings rather than DataSource.
As seen here: ComboBox SelectedItem vs SelectedValue .

But when I tried this code my ComboBox item list remained empty:

BindingSource comboBoxSelection1Binding = new BindingSource();
comboBoxSelection1.DataSource = SelectionList1;
comboBoxRuleCustomerGroup.DataBindings.Add("SelectedValue", comboBoxSelection1, "Name", true, DataSourceUpdateMode.OnPropertyChanged);

Any ideas?
Sorry for the overly complex issue, I keep having to write overly complex programs!

Answer 1

Did a more detailed search after thinking about this in depth over the weekend. My issue in searching before was not knowing really what was happening. I realise now that this is a problem when trying to bind multiple combo boxes to the same dataset.

Finally found this: Multiple ComboBox controls from the same Dataset

The answer is to add the line:

comboBoxSelection1.BindingContext = new BindingContext();

All credit to Blind Fury/John Saunders and Bytes.com.

Answer 2

You could try refactoring the code snippet starting with object[] to its own method passing in the ComboBox control and SelectionList.

private void PopulateList(ComboBox boxToPopulate, List<String> selectionList)
{
    object[] comboBoxList1 = new object[selectionList.Count];
    int i = 0;
    foreach (Selection s in selectionList)
    {
        string description = s.Description;
        comboBoxList1[i] = description;
        i++;
    }
    boxToPopulate.Items.AddRange(comboBoxList1);
}

Using this method you could have an unlimited number of ComboBoxes and uniquely fill them.

Answer 3

If you want to totally avoid using Datasource

You could add the items as a class instead fx

ComboBox1.Items.Add(new MyClass("Name", 1))

And then have the class

public class MyClass
    {
        private readonly string _Navn;
        public MyClass(string name, Int id)
        {
            Id = id;
            Name = name;
        }
        public int Id{ get; }
        public override string ToString()
        {
            return Name;
        }
    }

Then when you need the acces the id you do like so.

(ComboBox1.SelectedItem as MyClass).Id