filter by multiple blockchains in advanced search mode

[AlexTheLion123]

Summary

• User can only filter trading pairs by a single blockchain
• See @kenkunz reply on Discord:

tl;dr - yes, but requires some UI changes to how we generate filters options.

This is possible with Typesense, but requires some changes to how we auto-generate the available filter options. Currently, we're using the "facet" results to generate the filters and counts. Once you filter by a single blockchain, the other chains are not represented in the returned facet results.

In order to fix this, I think we would need to get the unfiltered facet results to identify available options… and merge this with the filtered facet results to display proper counts.