feat(index): provide scoped results to render hook

[francoischalifour]

Description

This introduces the concept of scoped results during the render hook.

Why

Since InstantSearch.js now handles multi-index search, we will need to revisit the behavior of some widgets:

• autocomplete may need to access the scope of its current index, as well as all the siblings and children
• currentRefinements may need to show the refinements coming from the current index and all its siblings/children
• clearRefinement may need to reset the refinements coming from the current index and all its siblings/children

Explanation

Behavior

An index now has access to all its children and siblings (+ siblings children) results. As illustrated in the image below, the lower in the tree, the fewer results the index has access to.

The more transparent a level is, the less view it has on the global results.

Render options interface

This information is given in the scopedResults key of the render options. The new interface is:

interface ScopedResult {
  indexId: string;
  results: SearchResults;
}

interface RenderOptions {
  instantSearchInstance: InstantSearch;
  templatesConfig: object;
  results: SearchResults;
  scopedResults: ScopedResult[]; // ← this is new
  state: SearchParameters;
  helper: Helper;
  searchMetadata: {
    isSearchStalled: boolean;
  };
  createURL(state: SearchParameters): string;
}

A scoped result contains an indexId and a results key. It always has a least one entry in scopedResults, being the current index and its own result. Once you start nesting indexes, more results appear in scopedResults.

• indexId: unique identifier of the results. This is not true for now because the indexId is the indexName and you can use the same index several times. We might later need to introduce an indexId option in the index widget.
• results: the results of the given index

[algobot]

Deploy preview for instantsearchjs ready!

Built with commit d1826e7

https://deploy-preview-3964--instantsearchjs.netlify.com

[eunjae-lee]

Btw, what did you use to draw that? That's 💯

[francoischalifour]

@eunjae-lee Good old Sketch haha

[eunjae-lee]

I've read the description and the files changed.
It looks good to me, but considering I'm not aware of the whole scope of the federated search yet, you'd better get approval from someone else :)

[Haroenv]

get xxx is ES5, so we could use it if we want, unrelated to this PR