UserControl does not appear to be using SET

Question

I have been strugling with this for a few hours now and I am simply running around in circles increasing my frustration level.

I have a rather straight forward user control, on this control is a label and a combo box. I have exposed public properties for changing the level text and created a GET/SET for DropDownItems.

The list containing my combo box items is declared as follows:

private List<DropdownItemObject> _dropDownItems = new List<DropdownItemObject>();

This class is the item(s) added to the combo box.

public class DropdownItemObject
{
    public DropdownItemObject()
    {
        Tag = null;
        Object = null;
    }

    public DropdownItemObject(string text, object _object = null, object tag = null)
    {
        Text = text;
        Object = _object;
        Tag = tag;
    }

    public object Tag { get; set; }

    public object Object { get; set; }

    public string Text { get; set; }

}

This is the exposed property in the UserControl. The combo box on the user control is called 'comboPrimary'.

[DesignerSerializationVisibility(DesignerSerializationVisibility.Content), Editor(typeof (CollectionEditor), typeof (UITypeEditor))]
        public List<DropdownItemObject> DropDownItems
        {
            get
            {
                return _dropDownItems;
            }
            set
            {
                _dropDownItems = value;
                comboPrimary.Items.Clear();

                foreach (DropdownItemObject item in _dropDownItems)
                {
                    comboPrimary.Items.Add(item);
                }
            }
        }

When this control is added to a form, I can use the Collections Editor to add the drop down items. Or I can do it programmatically with this:

uc1.DropDownItems.Add(new DropdownItemObject("ITEM 998"));

But, at run time no items appear in the drop down list.

Answer 1

DropDownItems.Add does not call the DropDownItems setter. You're not setting the value of the property, just calling a method on its current value.

You need to say something like

uc1.DropDownItems = new List<DropdownItemObject>() { 
    new DropdownItemObject("ITEM 998") };

in order to call the setter code.

You could also expose your own Add method on your UserControl class, which would in turn call comboPrimary.Items.Add.

public void Add(DropdownItemObject item) {
   comboPrimary.Items.Add(item);
}