split event with > 20 objectIDs

[eunjae-lee]

Since this PR #4841, an event with more than 20 objectIDs is split into multiple requests. Now that multiple events in a single request is supported in search-insights (algolia/search-insights.js#335), we can update InstantSearch.js as well to send a single request instead of many.

I propose to revert some of the part of the previous work, which is splitting payload and call instantSearchInstance.sendEventToInsights() multiple times. For those using onEvent hook to get the payload, this can be confusing because it's supposed to be a single callback for them. I think we can split the job within instantSearchInstance.sendEventToInsigths() method.

This line
https://github.com/algolia/instantsearch.js/blob/master/src/middlewares/createInsightsMiddleware.ts#L155:L155

can become something like this:

insightsClient('sendEvents', chunk(event.payload));

What do you think?

[Haroenv]

interesting, but won't that break people on older versions of search-insights?

[eunjae-lee]

yeah if we decide to this, then we should either do this in the next major version of InstantSearch.js, or put a big banner in the changelog?

[Haroenv]

yes, in a major version I see it as possible, but probably not before