How to implement Incremental Loading for ListView Items?

Question

I am making a UWP app. I have a ListView bound to an ObservableCollection. I want to find out when the end of ListView is reached. Once the end of ListView is reached, I have to make an API call to add more data to the List.

By end of ListView I mean that user has scrolled all the way down and I have to make a api call to get more data into the listview so that the user can scroll further.

How do I find out when the user has scrolled all the way down?

Please refine your question, show us some code and let us know which part of the code you're having a hard time with. What do you consider to be `the end of the ListView reached`? The user scrolled all the way down? Or your code is done populating the ListView? — blaze_125, May 26 '17 at 17:46
@blaze_125 Added to the question. There's nothing much with the code, only a ListView which takes items from an ObservableCollection. — ravi kumar, May 26 '17 at 17:57
Check this out to get started -> [handling-scroll-event-on-listview-in-c-sharp](https://stackoverflow.com/questions/1851620/handling-scroll-event-on-listview-in-c-sharp) It's not UWP specific but it may help you get going. — blaze_125, May 26 '17 at 18:15

score 3 · Accepted Answer · answered May 27 '17 at 06:52

Use Incremental Loading Collection Helpers in UWP Community Toolkit

using Microsoft.Toolkit.Uwp;

public class Person
{
    public string Name { get; set; }
}
public class PeopleSource : IIncrementalSource<Person>
{
    private readonly List<Person> people;

    public async Task<IEnumerable<InfoOverView>> GetPagedItemsAsync(int pageIndex, int pageSize, CancellationToken cancellationToken = default(CancellationToken))
    {
        return AddItems();
    }

    public void AddItems()
    {
        people.Clear();
        //Code to add the additional items in the people List
        return people;
    }
}

//In Page.xaml.cs
public Page()
{
    this.InitializeComponent();
    var collection = new IncrementalLoadingCollection<PeopleSource, Person>();
    MasterDetailsViewPanel.ItemsSource = collection;
}

A. Milto · Answer 2 · 2017-05-27T02:17:39.297

0

In the UWP Community Toolkit there's a special version of UWP ListView control called PullToRefreshListView that has a functional close to what you're looking for: when the user pulls down beyond the end of the list the RefreshRequested event is fired - this is where you add new items.

I suggest you go to the Windows Store and download UWP Community Toolkit Sample App to take a look at the demo of this control and have an example of code to start with.

edited May 27 '17 at 02:17

answered May 26 '17 at 18:17

A. Milto

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you should have recommended [`Incremental Loading Collection Helpers`](http://www.uwpcommunitytoolkit.com/en/master/helpers/IncrementalLoadingCollection/) – Vijay Nirmal May 27 '17 at 06:54

How to implement Incremental Loading for ListView Items?

2 Answers2