Error when binding WPF combobox ItemsSource to an Array of Strings

Question

I could not set a combobox's ItemsSource to an Array. I have tried setting the DataContext to the class where the Array is found, and then setting the bindings in XAML

 class Car
{
    public string[] makes;
}

...

public MainWindow()
{
    Car _Car = new Car();
    _Car.makes = new string[]
        {
            "Toyota",
            "Mitsubishi",
            "Audi",
            "BMW"           
        };

    this.DataContext = _Car;
}

and then in XAML

<ComboBox Name="cars" Grid.Column="0" 
              Grid.Row="0" Margin="5" 
              ItemsSource="{Binding Path=makes}"/>

It doesn't seem to do anything. My cars combobox won't have any items.

I've also tried explicitly assigning

cars.ItemsSource= new string[]{
                "Toyota",
                "Mitsubishi",
                "Audi",
                "BMW"           
            };

But then I get this error message:

Exception has been thrown by the target of an invocation.

Is there anything I missed?

Omri Btian · Accepted Answer · 2013-12-03 05:59:48Z

7

WPF binding doesn't support fields. Make it a property that has a getter and setter

class Car
{
    public string[] makes { get; set; }
}

Regardless, you do not have to explicitly state Path, so this should suffice

<ComboBox Name="cars" Grid.Column="0" 
          Grid.Row="0" Margin="5" 
          ItemsSource="{Binding makes}"/>

answered Dec 3, 2013 at 5:59

Omri Btian

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4 Comments

Carl Nathan Mier Over a year ago

wow. it worked, thanks!.. but how could it be, when 'makes' has already been set to 'public', which in my understanding is already accessible by other functions?

Omri Btian Over a year ago

@CarlNathanMier It is accessible, but this is not enough. WPF binding works on the PropertyDescriptor model which requires a property. you can read more about it here

Carl Nathan Mier Over a year ago

Thanks, but would you also know why assigning 'cars.ItemsSource= new string[]{ "Toyota", "Mitsubishi", "Audi", "BMW" };' returns the exception? thanks

Omri Btian Over a year ago

@CarlNathanMier My guess would be that you might set the ItemsSource twice, in the xaml ItemsSource="{Binding makes}" and in the code-behind, but you should look into the inner exception to get more details ...

Ramashankar · Accepted Answer · 2013-12-03 06:56:32Z

3

In Order for data binding to work correctly, you need a 'Property' to bind to.

XAML

<ComboBox Name="cars" Grid.Column="0" 
          Grid.Row="0" Margin="5" 
          ItemsSource="{Binding makes}"/>

Code

class Car
{
    public string[] makes { get; set; }
}

answered Dec 3, 2013 at 6:56

Ramashankar

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