How to bind to the list and swap at the same time?

Question

I have data about the form that I want to associate with lists. Combined fields must constantly display the same object and bind to different properties of the object, but one of them displays only a subset of all possible objects.

My objects can be described as:

{"q",#1,1},{"w",#1,2},{"e",#1,3},{"r",#2,6},{"t",#3,2},{"y",#3,6} etc 

The first combo box displays the first box and the full list, to be precise:

 "q","w","e","r","t","y" etc 

The second combo box displays the third field, but only for objects that have a similar second field with the currently selected object.

If {"q", # 1,1} is selected, it displays:

 1,2,3 

and if {"r", # 2,6} is selected, it will display:

 6 

Selecting another item in any of the combo boxes changes the currently selected item and (which accordingly updates the other relevant fields).

What is the most elegant or “right” way to do this using winforms data binding? (for me, elegat will not resort to handling changes to the currently selected item).

Answer 1

This can help:

 List<Tuple<string, string, int>> values = new List<Tuple<string, string, int>>(); 

Then:

 comboBox1.DisplayMember = "Item1"; comboBox1.DataSource = values; comboBox2.DisplayMember = "Item3"; var filter = ((Tuple<string, string, int>)comboBox1.SelectedItem).Item2; comboBox2.DataSource = values.Where(input => input.Item2 == filter); 

Answer 2

Create a property for each of your ComboBoxes to bind. Now, in fact, properties can be a LINQ expression, filtering the right data for you.

An example of such properties:

 private final List<MyObj> _allObjects = new List<MyObj>(); ... // fill the _allObjects somewhere public IEnumerable<MyObj> AllGoodObjects { get { return from o in _allObjects where o.IsGood select o; } } public IEnumerable<MyObj> AllBadObjects { get { return from o in _allObjects where !o.IsGood select o; } } 

You can create a complex query and practically select whatever you want.