windows store app Listview Binding

Question

I have a class with data:

public class routedata : INotifyPropertyChanged

{

    private List<double> distances;
    public List<double> Distances
    {
        get { return this.distances; }
        set
        {
            if (this.distances != value)
            {
                this.distances = value;
                this.onPropertyChanged("Distances");
            }
        }
    }

    private List<string> instructions;
    public List<string> Instructions
    {
        get { return this.instructions; }
        set
        {
            if (this.instructions != value)
            {
                this.instructions = value;
                this.onPropertyChanged("Instructions");
            }
        }
    }

    public event PropertyChangedEventHandler PropertyChanged;

    protected virtual void onPropertyChanged(string property)
    {
        if (this.PropertyChanged != null)
        {
            this.PropertyChanged(this, new PropertyChangedEventArgs(property));
        }
    }        
}

I'm trying to bind it to a listview like this:

     <GridView Name="routeView" HorizontalAlignment="Left" Height="310" Margin="1025,318,0,0" Grid.Row="1"      
           VerticalAlignment="Top" Width="340" >
            <ListView Name="routeList" Height="300" Width="330" ItemsSource="{Binding routeData}">
                <ListView.ItemTemplate>
                    <DataTemplate>
                        <StackPanel Orientation="Horizontal">
                            <TextBlock Text="{Binding Instructions}"
                                                      TextWrapping="Wrap" Width="200"/>
                            <TextBlock Text="{Binding Distances}"
                                                      Margin="10,0,0,0" />
                            <TextBlock Text="km"/>
                        </StackPanel>
                    </DataTemplate>
                </ListView.ItemTemplate>
            </ListView>
        </GridView>

I have in my c# code behind: routeList.datacontext = this;

but it is still not binding, only one empty row is populated in the listview. I have checked the data and it is all present. Any help would be appreciated thank you.

you have a single instance of routedata? or a list of routedata elements? Your GridView ItemsSource implies the latter. ItemSource should be set to a collection, and then in your template you assign UI elements to individual members of the class in that collection. You seem to have an inverted scenario. — Jim O'Neil
– Jim O'Neil, Commented Jan 26, 2013 at 21:41
I see. I have a single instance of route data. Should I just place the listview inside a grid? I tried this before and it still did not work. Thank you for response. — Hairlock
– Hairlock, Commented Jan 26, 2013 at 21:56
your route element is a single object and you have two different collections in it, but you're trying to pull both collections into a single grid, item by item. What would happen if the Instructions and Distances lists were different sizes? see @FilipSkakun answer below; you're data model is what needs a bit of modification and then the bindings will flow naturally. — Jim O'Neil
– Jim O'Neil, Commented Jan 26, 2013 at 22:13
I can guarantee that instructions and distances will always be the same. I got this working with an alternative method before but that was wasn't registering onselectionchanged handler properly. But am trying to implement the proper method atm. — Hairlock
– Hairlock, Commented Jan 26, 2013 at 22:47

Michael Celey · Accepted Answer · 2013-04-01 17:00:02Z

1

A ListView takes a single collection as ItemsSource, so if you want to display multiple TextBlocks for each item - you need a collection of objects with multiple text properties to bind to your DataTemplate. In your case a routeData is not a collection. Instead you need to define your item view model, e.g.

public class RoutePoint
{
    public double Distance { get; set; }
    public string Instruction { get; set; }
}

then you would bind your ListView.ItemSource to a List and in your DataTemplate bind it like that:

<TextBlock Text="{Binding Distance}"/>
<TextBlock Text="{Binding Instruction}"/>

You don't need to use an ObservableCollection if your collection never changes after you bind it to the ListView for the first time (SelectedItem doesn't constitute a change).

edited Apr 1, 2013 at 17:00

Michael Celey

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answered Jan 26, 2013 at 22:06

Filip Skakun

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2 Comments

Hairlock Over a year ago

Okay, i made the class like you said. I put it in an observable collection. I confirm the collection is populated with members and data. I set the datacontext of listview to the collection (i also tried setting it to "this"). And i set item source of listview to the collection. Still no go. Only thing i change in my data template was the name Instruction and Distance. It is still within a grid view. Stubborn thing is going to kill me.

Filip Skakun Over a year ago

What is your DataContext? Have you tried simply assigning the collection to ItemsSource in code behind? Can you share more of your code?

Daniel Kelley · Accepted Answer · 2013-01-26 20:59:09Z

0

If your view is called routeView, shouldn't your DataContext be set to a new instance of routedata? Also, I suggest you use an ObservableCollection<T> for your bindable collections rather than List<T>.

answered Jan 26, 2013 at 20:59

Daniel Kelley

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1 Comment

Hairlock Over a year ago

I tried your suggestions (observable collection and fiddling with datacontext) but it is still not displaying anything. Only a single row in the list view.

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