Question: Has anyone here implemented autocomplete feature of azure search with Sitecore? 

I see documentation on how to add a suggester while creating an index in azure, but Sitecore documentation (<https://doc.sitecore.net/sitecore_experience_platform/setting_up_and_maintaining/search_and_indexing/using_solr_autosuggest>) only mentions solr suggester configuration, and I don't see corresponding dlls for azure on nuget (Sitecore.ContentSearch.SolrProvider.dll, Sitecore.ContentSearch.SolrNetExtension.dll)

Any ideas?

Answer: 
Azure does not support solr suggester for sitecore, but as a workaround you can create a separate index where you store only text information that you want to use for suggestions (to get suggestions fast) that you will be use like a suggester dictionary.

Example of suggesting by field "Title":

```
public class TitleSearchResultItem
{
    [IndexField("title")]
    public string Title { get; set; }
}

```

Suggest method:

```
public IEnumerable<string> Suggest(string term, int count = 5)
{
            char[] delimiters = { ' ', ',', ';', '.', ':', '-' };

            var words = term.Split(delimiters, StringSplitOptions.RemoveEmptyEntries);

            var predicate = PredicateBuilder.True<TitleSearchResultItem>();
            predicate = words.Aggregate(predicate, (current, t) =>
            {
                return current.And(x => x.Title.StartsWith(t).Boost(10) || x.Title.Contains(t).Boost(5));
            });

            var contextIndex = _contextRepository.GetSearchIndexContext("custom_suggester_index");
            using (var context = contextIndex.CreateSearchContext())
            {
                var results = context.GetQueryable<TitleSearchResultItem>()
                    .Where(predicate)
                    .Take(count)
                    .Select(x => new { x.Title });

                return results.Select(x => x.Title).ToList();
            }
}

```
Following list for features that exist in Azure that are not currently supported by your Sitecore provider:

* Geospatial data types
* Indexers
* Suggestions
* Highlighters

Source: [Sitecore Azure Search overview](https://doc.sitecore.com/developers/91/platform-administration-and-architecture/en/sitecore-azure-search-overview.html#UUID-a5758458-5dbe-ed52-718c-6cd25db7348b_section-idm46485168419808)