[Feature requested] ListView do not ScrollTo a group when there is no child of this group.

[jessiezh0320]

Description

At present, we must special a item object as the first parameter of method : ScrollTo .
https://docs.microsoft.com/en-us/dotnet/api/xamarin.forms.listview.scrollto?view=xamarin-forms

When a group of listview has no child, the function ScrollTo cannot scroll to the corresponding group.

Many customers think it is not reasonable, and it should have this feature.

Expected Behavior

When a group of listview has no child, the function ScrollTo should scroll to the corresponding group.

Actual Behavior

When a group of listview has no child, the function ScrollTo cannot scroll to the corresponding group.

Basic Information

[techduggu]

I'd like to pick this up. Currently trying to reproduce it and I also noticed that it doesn't Scroll if list item (first parameter) is passed as null (in-case I'd like to scroll to a group only). For e.g.

List.ScrollTo(null, mygroupitem, ScrollToPosition.MakeVisible, true);

@jsuarezruiz @jfversluis Is it expected behavior or should I fix this too?

Thanks!

[jfversluis]

Makes sense to me to scroll to the group whenever the item is not found but the group is. I guess the cases for the different parameter values would be:

• No item, do have a group: go to the group
• Do have an item, no group: find the first item throughout all the groups and scroll there
• Have an item and have a group: find the item in the specified group and scroll there. If the item isn't found, scroll to the group
• No item, no group: doesn't make any sense, do nothing

Right?

[Rajeswari06]

We are facing the same issue in iPad-iOS 12.4.1. with grouped listView.

We have used a grouped listview, when we try to expand and collapse an item in bottom of the screen scroll position is changing to top and unable to see the selected item.

Listview.scroll is not working in grouped listview if it don't have items.

[jfversluis]

There is a PR for the Android side of things @Rajeswari06 if you're brave enough you could add the iOS implementation? 😉

[techduggu]

@Rajeswari06 When I fixed for Android, I had seen the existing implementation for iOS too as it also uses the TemplatedItemsList.cs from Core library and it requires little tweaks at the iOS ListViewRenderer.cs at the following LOC:

if (results.Item1 == -1 || (results.Item1 == -1 && results.Item2 == -1))
return;

You can refer the PR #8310 for more details. I couldn't complete the iOS as I don't have mac/iOS but if you'd like to pick this up, I'm happy to help should you have any further questions.

[samhouts]

closed by #8310