SelectedItem and ComboBox

Seems like it is once a month where someone is having trouble setting the selectedItem of a ComboBox. The key is that the ComboBox does an exact reference match on the items in the dataProvider. It doesnt take the time to compare values within the dataProvider items with the values in the item you are setting as the selectedItem.
In other words, if you have an array of objects:

[{ firstName: "Alex", lastName: "Harris" }, { firstname: "Alex", lastName: "Harui"}, {firstName: "Alex", lastName: "Trebek"}]

you can’t just set:

selectedItem = { firstName: “Alex”, lastName: “Harui }

as that assigns the selectedItem to a different Object instance with the same values. The ComboBox class will simply look to see if there is a reference to that instance in its dataProvider, which there is not. Instead, you have to scan the dataprovider and match up values.
So many folks are doing this, that I decided to post an example so we don’t have to keep writing that scan-the-dataprovider loop. This example tries for an exact match first, so if you know you’ll never have an exact match you can save more time by cutting out that first call to super.selectedItem = value;
Source for ComboBox subclass
Test file source
Helper class source for Test file
Test file
Usual caveats apply.