WPF组合框值

Question

I have three combo boxes on a xaml window :

<Grid>
    <ComboBox Name="cbo1" Margin="40,37,328,250"  SelectionChanged="OnComboBoxChanged" />
    <ComboBox Name="cbo2" Margin="40,145,328,142" SelectionChanged="OnComboBoxChanged"/>
    <ComboBox Name="cbo3" Margin="40,91,328,196" SelectionChanged="OnComboBoxChanged" />
</Grid>

I assign the value to these on load , I am working on writing a routine that can loop through an array which has the names for these combo boxes and get the selected value :

string[] comboNameLst = {"cbo1","cbo2" , "cbo3" }; 
foreach (string s in comboNameLst)
{                
    ComboBox cbo = new ComboBox();
    cbo.Name = s;

    MessageBox.Show("ID is" + id + "and cbo is" + cbo.Name);
    MessageBox.Show("selected item" + cbo.SelectedItem  );
}

I am getting the value as null. I need to be able to get selected values for these drop downs I know I could use the logical tree helper loop through all the objects and get the value but I dont want to be able to do it that way as I have too many controls and it will be very tricky.

Answer 1

Instead of creating a new combo box in your loop, you need to actually use the boxes from your UI:

ComboBox[] comboNameLst = {cbo1, cbo2, cbo3}; 
foreach (ComboBox cbo in comboNameLst)
{                
    MessageBox.Show("ID is" + id + "and cbo is" + cbo.Name);
    MessageBox.Show("selected item" + cbo.SelectedItem  );
}

Answer 2

I would also like to point out that you can avoid this type of code completely with binding. You can bind properties to the combo boxes using ItemsSource and bind a property to SelectedValue like so.

<ComboBox ItemsSource="{Binding ListProperty}" 
            DisplayMemberPath="ValueString" 
            SelectedValuePath="ValueString" 
            SelectedValue="{Binding SelectedValueProperty}" />

This will provide the currently selected values directly to your bound properties for use in your code without the grunt work of adding items and getting their currently selected values via code-behind.

Here is an article for more detail.

I hope this helps.