Incorrect number of hits on HitsInteractor when using pagination (infinitescroll)

[steffidg]

Describe the bug 🐛 With infinitescroll the HitsInteractor returns an incorrect number of hits after query is changed with hits less than the previous one.

To Reproduce 🔍 Steps to reproduce the behavior:

Pre-req: On example project, configure Paging Single Index to support applying of filter that will return less hits than the default

1. Go to Paging Single Index
2. Scroll down to at least 3 pages or more (roughly you'll be at numberOfHits=80 and above)
3. Apply filter (this filter should have a result that is less than the number of hits pre-filter)
4. See error.

Expected behavior 💭 HitsInteractor.numberOfHits should return the numbers from step 3 but it returns step 2 numbers.

Here's a demo video: https://user-images.githubusercontent.com/81630747/195762256-fada5382-119f-4eb6-ba82-4fdf141a1080.mov Note: On the demo, I'm using our own indices.

Environment:

• OS: iOS
• Version: 15.5
• InstantSearch: 7.21

Additional context

• Seems like it only happens when you've loaded other pages. If you skip step 2, bug doesn't occur.
• With the bug, you'll encounter a scenario wherein HitsInteractor.numberOfHits is more than SearchStat.totalNumberOfHits. As a result, it messes up the UI. As a temp solution, I had to create a conditional check like this to determine the correct item count to display

  if hitsSource.numberOfHits() > stats.totalHitsCount {
      return stats.totalHitsCount
  }
   return hitsSource.numberOfHits()

[VladislavFitz]

Hi @steffidg , Could you make sure that the HitsInteractor instance is connected to the FilterState using the connectFilterState method in your example? This connection ensures resetting the cached hits stored in the HitsInteractor whenever the FilterState changed.

[steffidg]

Hi @VladislavFitz Tried it but unfortunately I'm still getting the incorrect number of hits.

class EcommerceDemoController {

    let searcher: HitsSearcher
    let hitsInteractor: HitsInteractor<Hit<StoreItem>>
    let searchBoxConnector: SearchBoxConnector
    let statsConnector: StatsConnector
    let loadingConnector: LoadingConnector
    let filterState: FilterState = .init()

    init(searchTriggeringMode: SearchTriggeringMode = .searchAsYouType) {
        let client = SearchClient(appID: "appid", apiKey: "apikey")
        Logger.minSeverityLevel = .trace
        searcher = .init(client: client, indexName: "indexname")
        searcher.connectFilterState(filterState)

// Connectors
       searchBoxConnector = .init(searcher: searcher, searchTriggeringMode: searchTriggeringMode)
        statsConnector = .init(searcher: searcher)
        loadingConnector = .init(searcher: searcher)

// Interactor
        let decoder = JSONDecoder()
        decoder.keyDecodingStrategy = .convertFromSnakeCase
        hitsInteractor = .init(jsonDecoder: decoder)
        hitsInteractor.connectFilterState(filterState)
        hitsInteractor.connectSearcher(searcher)
    }

// Called on tap of apply filters button    
    func applyFilters() {
        filterState[and: "conjunctiveGroup"].add(Filter.Facet(attribute: "price.range", stringValue: "₱500-₱1,500"))
        filterState[and: "conjunctiveGroup"].add(Filter.Facet(attribute: "stock.stock_label", stringValue: "In Stock"))
        filterState[and: "conjunctiveGroup"].add(Filter.Facet.init(attribute: "reviews.average_rating", stringValue: "5"))
        searcher.search()
    }
}

[VladislavFitz]

Hi @steffidg, I slightly modified the demo application to reproduce the issue you reported. You can find it in the branch hits-count-issue branch. Please try it by launching the PagingSingleIndex target of the Examples application. I logged the same data as you in your example and it works as expected.

[steffidg]

Hi @VladislavFitz Oh. I see! Yes it works fine now. Appreciate the help!