Index analyzer not working with Elasticsearch.net And Nest

You create a custom analyzer but you don't send it to Elasticsearch, so when it comes to using it in a mapping, Elasticsearch knows nothing about the custom analyzer.

You can create a new index with analysis and mappings in one request. Here's an example of creating an index, adding your custom analyzer and mapping as part of the index creation

void Main()
{
    var node = new SingleNodeConnectionPool(new Uri("http://localhost:9200"));
    var settings = new ConnectionSettings(node)
        // set "aa" as the default index; if no index
        // is specified for a type or in the request, 
        // the default index will be used
        .DefaultIndex("aa");

    var client = new ElasticClient(settings);

    var indexExistsResponse = client.IndexExists("aa");
    if (indexExistsResponse.Exists)
    {
        client.DeleteIndex("aa", null);
    }

    var people = new List<Person>{
        new Person
        {
            id = 1,
            Firstname = "an apples bananas  boxes, the sun.",
            Lastname = "a beautiful womens with a good guys in there"
        }
    };

    var createIndexResponse = client.CreateIndex("aa", c => c
        .Settings(s => s
            .Analysis(a => a
                .Analyzers(ad => ad
                    // give the custom analyzer a name
                    .Custom("ilhee_Custom", ca => ca
                        .Tokenizer("standard")
                        .Filters("lowercase", "stop", "standard", "snowball")
                    )
                )
            )
        )
        .Mappings(m => m
            .Map<Person>(d => d
                .Properties(props => props
                   .String(s => s
                       .Name(p => p.Firstname)
                       .Analyzer("ilhee_Custom")
                   )
                   .String(s1 => s1
                       .Name(p1 => p1.Lastname)
                       .NotAnalyzed()
                    )
                )
            )
        )   
    );

    var indexManyResponse = client.IndexMany<Person>(people, "aa");

    // refresh the index after indexing, so that newly indexed documents
    // are available in search results.
    client.Refresh("aa");

    var searchResponse = client.Search<Person>(s => s
        .Query(q => q
            .Match(m => m
                .Field(p => p.Firstname)
                .Query("boxes")
            )
        )
    );
}


public class Person
{
    public int id { get; set; }
    public string Firstname { get; set; }
    public string Lastname { get; set;}
}

The search returns back our indexed document as expected

{
  "took" : 9,
  "timed_out" : false,
  "_shards" : {
    "total" : 5,
    "successful" : 5,
    "failed" : 0
  },
  "hits" : {
    "total" : 1,
    "max_score" : 0.15342641,
    "hits" : [ {
      "_index" : "aa",
      "_type" : "person",
      "_id" : "1",
      "_score" : 0.15342641,
      "_source" : {
        "id" : 1,
        "firstname" : "an apples bananas  boxes, the sun.",
        "lastname" : "a beautiful womens with a good guys in there"
      }
    } ]
  }
}