Searching in facet indices

[francoischalifour]

Since InstantSearch.js v4, we introduced the index widget that allows to target multiple Algolia indices in a single instantsearch instance—and what if we allowed to also target facet indices?

Motivation

When building advanced search interfaces, you often need to search through "hidden" data at first glance (e.g., hit categories) to allow to centralize all filters in a single search box.

Here's an example in a Pokédex application, where I search Pokémon and their abilities at the same time, to allow to refine the search.

I had to use the search client for this. As a user, I would expect to be able to use a facetIndex widget to search through these values.

Proposed usage

A facet index could act as an index, where its widgets inherit from its context: a nested search box would target a facet index (through a SFFV endpoint), a hits widget would display facet hits, etc.

Using the React syntax for convenience:

function App() {
  return (
    <InstantSearch>
      <FacetIndex facetName="brand">
        <Configure maxFacetHits={5} />

        {/* Sets the `facetQuery` search parameter when in a facet index */}
        <SearchBox />

        {/* Reads from the `facetHits` response when in a facet index */}
        <Hits />
      </FacetIndex>
    </InstantSearch>
  );
}

Am I the only one in need for such a feature?

[Haroenv]

How do the other widgets make sense in a "facet index"? Would they just throw an error?

[francoischalifour]

I would say so. What would you see?

[Haroenv]

in InstantSearch.js I would expect that error to happen in addWidgets, it could filter accepted child widgets for FacetIndex begin hits / searchbox, maybe refinementList & menu on the attribute you're in (to be able to refine)

[francoischalifour]

If we take things further, we could even statically prevent users from these errors with ESLint rules.