WPF Combobox with string Bind to Int property

Question

I want a Combobox with numbers 1-8 and bind the selected value to a property "NumberOfZones" of int type. By default, combobox returns string value so this can't be saved in int property. How do I type cast it to int.

How do I set items and make selection in int.

   <ComboBox Background="#FFB7B39D" Height="23" Name="cboNumZones" Width="74" Margin="158,16,368,247" Grid.Row="2" SelectionChanged="cboNumZones_SelectionChanged" 
    SelectedValue="{Binding Path=NumberOfZones, Mode=TwoWay}">
   </ComboBox>
                <!--
                <ComboBoxItem >1</ComboBoxItem>
                    <ComboBoxItem >2</ComboBoxItem>
                    <ComboBoxItem >3</ComboBoxItem>
                    <ComboBoxItem >4</ComboBoxItem>
                    <ComboBoxItem >5</ComboBoxItem>
                    <ComboBoxItem >6</ComboBoxItem>
                    <ComboBoxItem >7</ComboBoxItem>
                    <ComboBoxItem >8</ComboBoxItem>
                -->

The object that contains NumberOfZones property is the DataContext of the UserControl.

Many Many Thanks.

Solution 1

You are mistaken about what a ComboBox returns. Yours returns string values because that's what you put into it. If instead you create a property where your NumberOfZones property was declared:

public ObservableCollection<int> Numbers { get; set; }

And then data bind that to your ComboBox:

<ComboBox ItemSource="{Binding Numbers}" Background="#FFB7B39D" Height="23" 
    Name="cboNumZones" Width="74" Margin="158,16,368,247" Grid.Row="2" 
    SelectionChanged="cboNumZones_SelectionChanged" SelectedValue="{
    Binding Path=NumberOfZones, Mode=TwoWay}">

Then your selected number will be an int too.

Solution 2

You can set ItemsSource as array of int, then SelectedItem will be of int32 type:

<ComboBox SelectedItem="{Binding Path=NumberOfZones, Mode=TwoWay}">             
   <ComboBox.ItemsSource>
      <x:Array Type="{x:Type sys:Int32}">
         <sys:Int32>1</sys:Int32>
         <sys:Int32>2</sys:Int32>
         <sys:Int32>3</sys:Int32>
         <sys:Int32>4</sys:Int32>
         <sys:Int32>5</sys:Int32>
         <sys:Int32>6</sys:Int32>
         <sys:Int32>7</sys:Int32>
         <sys:Int32>8</sys:Int32>
      </x:Array>
   </ComboBox.ItemsSource>
</ComboBox>

for this you'll need to add sys: namespace to your XAML:

xmlns:sys="clr-namespace:System;assembly=mscorlib"

Solution 3

I know the question is for WPF, but just in case you are looking for the answer on Windows 8.1 (WinRT, Universal Apps) it would be:

<ComboBox SelectedItem="{Binding NumberOfZones, Mode=TwoWay}">
    <x:Int32>1</x:Int32>
    <x:Int32>2</x:Int32>
    <x:Int32>3</x:Int32>
    <x:Int32>4</x:Int32>
    <x:Int32>5</x:Int32>
</ComboBox>

given that

xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"

Comments

[Tvd]

Sheridan, of how wrong I was. Yes your code did the work as you said and even two way was successful. This solution solves my this Q. My other problem - I want to keep the Numbers property common as it is used other places of the app. I am not able to achieve that binding. I have shared it here - stackoverflow.com/questions/18493749/… . Please check out if you can suggest such cool and best option for the same.

[Tvd]

thanks for your response. Sheridan's solution suits more in my app. Thanks.

[Dave]

Will this still work if the program is built 64-bit?