有关数据绑定和修改UI控件的WinForms设计问题

Question

I have a WinForms app that contains a combobox (comboBoxMain) and several other controls. comboBoxMain is bound to an array of 5 objects (instances of a data class that contain several properties) and is used to select which of the 5 objects will have their properties displayed in the other UI controls. Once the user has selected the desired values in all of the controls on my form, I have a button that will copy those values to each of the other 4 instances of the data class. A few of the controls on my form can impact the visibility, enabled/disabled state or selected value of other controls. For example, if a user were to select a value of "Disabled" from one of the comboboxes (let's call it comboBoxStatus), that would result in three other controls being disabled, a checkbox being checked and the title of a groupbox being changed. The problem I'm having with this functionality can be described by the following scenario:

1. The user selects a value of "Disabled" in comboBoxStatus (which then triggers code in its SelectionChangeCommitted() event handler that modifies the other controls as I described above).

2. Next, the user clicks the button to copy the currently selected values in all of the controls to the other 4 data objects.

3. Finally, the user selects one of the other 4 data objects from comboBoxMain.

When this happens, I have a SelectionChangeCommitted() event handler for comboBoxMain that fires and looks at the SelectedValue in comboBoxStatus. Unfortunately, it sees the default value for the backing property instead of a value of "Disabled" which was copied to the property earlier. I have code at the end of comboBoxMain_SelectionChangeCommitted() which is supposed to check the values of those controls that could impact other things in the UI and make sure that everything gets updated appropriately. This obviously doesn't happen though, since it's not seeing the correct value. If I move that code out of the event handler and manually call it via a button press after the UI has bound the data for the currently selected data object, then it works. I can only guess that this happens because the bindings aren't updated until after comboBoxMain_SelectionChangeCommitted() has exited?

I hope that all makes sense. I've been playing with this for hours and have yet to completely understand what's happening or what the best solution to this problem is. If you've got any thoughts, I'd appreciate hearing them. Thanks for reading!

Answer 1

通过将SelectionChangeCommitted事件处理程序中的代码移动到SelectedIndexChanged事件处理程序中，我能够解决此问题。