Case insensitive sorting using normalizer

[CesarPozo (Cesar)]

Hello, I am using elasticsearch 7.5 and NEST client.

I want to sort a query, and as you know, by default does A..Za..z. I want it to be case insensitive.

I am trying to use a normalizer as is explained here:

Case insensitive sort doesn't work

To sort case-insensitively on a keyword field, you can apply a normalizer to that field. You can think of normalizers as analyzers for keyword fields instead of text fields. So, instead of defining an analyzer in your settings, define a normalizer: PUT /testindex { "settings": { "analysis": { "normalizer": { "case_insensitive": { "filter": "lowercase" } } } } } Next, apply that normalizer to your keyword field in your mapping: PUT /testindex/_…

PUT /testindex
{
  "settings": {
     "analysis": {
       "normalizer": {
         "case_insensitive": {
            "filter": "lowercase"
         }
        }
       }
     }
}

And then I could use it in the mapping:

PUT /testindex/_mapping/testmapping
{
  "properties": {
    "Id": {
    "type": "keyword"
    },
    "Name": {
      "type": "text",
      "fields": {
        "keyword": {
          "type": "keyword",
          "normalizer": "case_insensitive"
        }
      }
     }
   }
}

The problem it comes when I try to do it on the NEST client:

client.Indices.Create("testindex", e => e
                .Settings(s => s
                    .Analysis(a => a
                        .Normalizers(n => n.Custom("case_insensitive",c => c.Filters("lowercase")))))
                .Map(m => m
                    .Properties(p => p
                       .Text(st => st.Name("Name")
                       **.NORMALIZER**)))
            );

There is no way to add the normalizer the Name property field.

Any idea?

Thanks a million

[CesarPozo (Cesar)]

The question has been answered here by Rob:

Elasticsearch 7.x case insensitive sorting using normalizer

This property is part of keyword type properties as docs say.

The normalizer property of keyword fields is similar to analyzer except that it guarantees that the analysis chain produces a single token.

Simply changing your prop. to keyword field will allow you to place normalizer

await client.Indices.CreateAsync("testindex", e => e
    .Settings(s => s
        .Analysis(a => a
            .Normalizers(n => n.Custom("case_insensitive", c => c.Filters("lowercase")))))
    .Map(m => m
        .Properties(p => p
            .Keyword(st => st.Normalizer("case_insensitive").Name("Name"))))
);

[Martijn_Laarman]

Normalizer is only available on keyword fields, you were nearly there with mapping the provided example to csharp. You still need to introduce the Fields for Name

var response2 = Client.Indices.Create("testindex", e => e
	.Settings(s => s
		.Analysis(a => a
			.Normalizers(n => n.Custom("case_insensitive", c => c.Filters("lowercase")))))
	.Map(m => m
		.Properties(p => p
			.Text(st => st
				.Name("Name")
				.Fields(f => f
					.Keyword(kw => kw.Name("Keyword").Normalizer("case_insensitive"))
				)
			)
		)
	)
);

You can now sort on Name.Keyword.

[CesarPozo (Cesar)]

Thanks a million!