How to get data from a LongListSelector item in WP

问题:

So I have a LongListSelector that will soon be bound to a list of object.

What I want is when one of the LongListSelectorItems is tapped that I get the specific object tapped, and have the ability to pass that object to another screen so I can show full information about the object

private void PeopleList_Tap_1(object sender, System.Windows.Input.GestureEventArgs e)
    { 
        MessageBox.Show("SUCCESS");
    }

My Tap is working, I just don't know how to get the object that was selected, or how to pass it to another page using NavigationService

回答1:

You can use SelectionChanged event and LongListSelector.SelectedItem property to get selected item.

回答2:

Below is pulled straight from my latest app.

You can't directly pass an object, but you can pass text data. In my case, an id:

private void WishListBoxSelectionChanged(object sender, SelectionChangedEventArgs e)
{
    if (WishListBox != null && WishListBox.SelectedItem != null)
    {
        var selectedItem = (Models.Gift)WishListBox.SelectedItem;
        WishListBox.SelectedIndex = -1;
        var id = selectedItem.Id;
        NavigationService.Navigate(new Uri("/Views/Gift/GiftView.xaml?action=load&id=" + id, UriKind.Relative));
    }
}

then on the receiving end:

protected override void OnNavigatedTo(System.Windows.Navigation.NavigationEventArgs e)
{
    base.OnNavigatedTo(e);
    if (NavigationContext.QueryString.ContainsKey("action"))
    {
        if (NavigationContext.QueryString["action"]=="load")
        {
            PageTitle.Text = "edit gift";
            giftVm.Gift = App._context.Gifts.Single(g => g.Id == Int32.Parse(NavigationContext.QueryString["id"]));                    
        }
        else if (NavigationContext.QueryString["action"] == "new")
        {
            PageTitle.Text = "new gift";
        }
        else if (NavigationContext.QueryString["action"] == "newWishList")
        {
            App.vm = ((MainViewModel)App.vm).Me;
        }
    }
    else
    {
        MessageBox.Show("NavigationContext.QueryString.ContainsKey('action') is false");
    }
}

In my case, the data is stored in a DB. I simply cast the selected item to the correct object type, then check its ID and pass that to the next page where I do a lookup.

I hope this helps.