CODEWITHSUNDEEP
c#wpfdata-bindingcomboboxwpf-controls
ProfK
ProfK

Reputation: 51094

What is wrong with my data binding on a ComboBox?

I have a ComboBox marked up as:

<ComboBox x:Name="TitleCombo"
            Width="100" 
            Height="20"
            DisplayMemberPath="TITLE_NAME"     
            SelectedValuePath="TITLE_CODEID"     
            DataContext="{Binding}"
            ItemsSource="{Binding Path=Titles}" />

It is the sole control on NoticeWindow.xaml, which has the following code-behind:

public partial class NoticeWindow : Window
{
    private readonly Xt900Context _dbContext = new Xt900Context();
    public NoticeWindow()
    {
        InitializeComponent();
        var tits = _dbContext.TITLEs.ToList();
        Titles = new ObservableCollection<TITLE>(tits);
        DataContext = this;
        TitleCombo.ItemsSource = Titles;
    }
    ObservableCollection<TITLE> Titles { get; set; }
}

Without the TitleCombo.ItemsSource = Titles statement, the ComboBox remains blank. Why is this?

Upvotes: 0

Views: 121

Answers (2)

Omri Btian
Omri Btian

Reputation: 6547

So, your ComboBox is inside NoticeWindow, which has it's DataContext set to himself. This is also where you defined the Titles property.

Like @AirL pointed out, Titles should be marked as Public:

public ObservableCollection<TITLE> Titles { get; set; }

Also, there is no need defining a DataContext on the ComboBox nor stating TitleCombo.ItemsSource = Titles;

Since the ComboBox inherits its DataContext from the NoticeWindow. You can just bind it to the Titles property

<ComboBox x:Name="TitleCombo"
        Width="100" 
        Height="20"
        DisplayMemberPath="TITLE_NAME"     
        SelectedValuePath="TITLE_CODEID"     
        ItemsSource="{Binding Titles}" />

Upvotes: 2

AirL
AirL

Reputation: 1917

In the code you provided to us, your ObservableCollection<TITLE> Titles { get; set; } is defined as private (no access modifier being defined and private being the default one).

Given WPF databinding only works with public properties (see MSDN related documentation), it could explain why your binding isn't working properly and that you need to explicitly set your ItemsSource in code behind to fill your ComboBox.

The properties you use as binding source properties for a binding must be public properties of your class. Explicitly defined interface properties cannot be accessed for binding purposes, nor can protected, private, internal, or virtual properties that have no base implementation.

Upvotes: 0

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