Consider using ElasticSearch's suggesters and/or fuzziness on search

[raquelalegre]

ElasticSearch provides some functionality we could use to present users with suggestions when they mistype words. Have a look at Suggesters and Fuzzy Queries. Note those two link to ES 7.1, and I'm not sure which ES version we are using right now :)

[ageorgou]

In particular for search-as-you-type suggestions, we may want a combination of a completion suggester and a term suggester (for misspellings). Although the completion suggester also has a fuzziness setting, which may be enough.

The term suggester seems simple to add. The completion one requires some setup at index time, and maybe some configuration (e.g. filtering the _source to reduce data size, as suggested in the docs). We should be able to use both at the same time with a single query. The elasticsearch_dsl library doesn't seem to have a special API for suggestions, but we can just use the normal search() method.

The other option for completion suggestions is storing shingles/ngrams at index time, although that seems more involved (and I haven't found any docs for more recent versions). There is also apparently a search-as-you-type field type coming in future versions.

[ageorgou]

A useful tutorial for setting up a completion suggester (even though the interface has changed slightly, the steps seem to be the same).