SectionList misses scrollTo* methods

[nihgwu]

I'm planning to switch from ListView to SectionList, but find that I can't perform any scrollTo* methods, they are defined in VirtualizedList but not in VirtualizedSectionList. At least scrollToOffset should be implemented.

I'd like to send a PR, but I'm afraid to break the docs, and I don't know whether should we implement scrollToIndex and scrollToItem as they are different from FlatList

Perhaps a new method scrollToSection could be added too, it's a common use case in a contact list

@sahrens

[sahrens]

Yeah I punted on this but I agree it's important. Maybe scrollToIndexInSection({sectionKey: string, index: number})?

[nihgwu]

IMO, scrollTo* is a bit complex, especially the scrollToOffset({ animated: boolean?, offset: number }), now that it receives a object, what about simplify them to a single method scrollTo(params) where the params is in a shape of { animated: boolean?, offset: number?, index: number?, item: object?, sectionKey: string? } or scrollToOffset(offset: number, animated: boolean?)

And the renderItem(info: {item: object, index: number}) -> renderItem(item: object, index: number)

Those are just some of my thoughts when I'm trying to switch from ListView to SectionList

Thanks for your great effort to create such a wonderful component

[sahrens]

I appreciate the input, but here is the reasoning:

scrollTo* is more explicit and makes the API more clearly self documenting and simpler to flow-type, especially with composition.

renderItem(info: {...}) makes it easier to pull out just the info you care about in an order-independent way, and gives us the option value to add more data in the future in a backwards compatible way.

[jpshelley]

Has anyone started work on this? Don't want to duplicate efforts if so, otherwise I may have time to try it out. Although I'll defer to @sahrens if he already has thoughts on how to implement 😄

[sahrens]

No one is working on it to my knowledge so a PR would be appreciated :)

Just need to figure out the right API since we need to account for sections. I'll let you take a stab at it and we can iterate in review, just cc me in the PR summary.

[nihgwu]

@jpshelley 👍

[NicolasSandri]

@jpshelley, can you have a look to sticky section header support too? ;)

[jpshelley]

@MediaXtend PRs get merged faster if broken into smaller 'sections', so you should probably submit a new issue for it.

[sahrens]

Sticky headers are already in master.

[NicolasSandri]

@jpshelley, got it for the next time! 😇
@sahrens, I thought they were not because I've read:

Sticky headers are not yet supported.

(https://github.com/facebook/react-native/blob/master/Libraries/Lists/SectionList.js#L111)

If you need sticky section header support, use ListView for now.

(https://github.com/facebook/react-native/blob/master/Libraries/Lists/SectionList.js#L149)

I have to test this.

[sahrens]

Oh ha, forgot to update that comment!

[jpshelley]

@sahrens I started a branch on this work here and wanted to get your (and others) thoughts on the API.
https://github.com/jpshelley/react-native/tree/SectionList-AddScrollToSupport

I'm basically just making a wrapper call to the underlying VirtualizedSectionList which calls the VirtualizedList. The scrollToEnd is a fairly trivial function to show the implementation, with scrollToIndexInSection a suitable next candidate to add imo and which could take a little bit more work.

• Thoughts on the implementation?
• Thoughts on how many methods we should add before submitting a PR (scrollToEnd, scrollToIndexInSection, etc like the FlatList)?

[sahrens]

An internal client needed scrollToIndexAtSection support so I already added it in master (as scrollToLocation - maybe naming could be better, what do you think?). I think scrollToEnd can be done via getScrollResponder so not a big deal, but if you want to put up a PR for it I'll take a look.

[jpshelley]

We might end up using https://github.com/expo/react-native-invertible-scroll-view for our ScrollComponent for what I'm working on anyways so good timing 😄 We can ditch the branch I created in favor of yours and probably close this issue if @nihgwu agrees

[postalPain]

The 44-th version has been released but scrollTo method is not added :(
When are you going to release it?