public SimpleViewModel()
{
var dataSource = new FakeDataSource();
Items = new InfiniteScrollCollection <DataItem>
{
OnLoadMore = async() =>
{
// load the next page
var page = Items.Count / PageSize;
var items = await dataSource.GetItemsAsync(page + 1, PageSize);
return(items);
}
};
RefreshCommand = new Command(() =>
{
// clear and start again
Items.Clear();
Items.LoadMoreAsync();
});
// load the initial data
Items.LoadMoreAsync();
}
public GroupedViewModel()
{
var dataSource = new FakeDataSource();
Items = new InfiniteScrollCollection <GroupCollection <DataItem> >
{
OnLoadMore = async() =>
{
// load the next page
var page = Items.Sum(i => i.Count) / PageSize;
var items = await dataSource.GetItemsAsync(page + 1, PageSize);
// go through each group from the server
foreach (var group in items.GroupBy(i => i.Group))
{
// look to see if these items belong to any existing groups
var inList = Items.LastOrDefault(i => i.Group == group.Key);
if (inList != null)
{
// this is an existing group, so add the items to that
foreach (var item in group)
{
inList.Add(item);
}
// TODO: instead of adding each item individually, we could make use of
// the RangedObservableCollection from the NuGet:
// https://github.com/mattleibow/RangedObservableCollection
// this would become:
//
// inList.AddRange(group);
}
else
{
// this is a new group
Items.Add(new GroupCollection <DataItem>(group)
{
Group = group.Key
});
}
}
return(null); // we have added the items ourselves
}
};
RefreshCommand = new Command(() =>
{
// clear and start again
Items.Clear();
Items.LoadMoreAsync();
});
// load the initial data
Items.LoadMoreAsync();
}