case insensitive elasticsearch with uppercase or lowercase

Question

I am working with elastic search and I am facing a problem. if any body gave me a hint , I will really thankful.

I want to analyze a field "name" or "description" which consist of different entries . e.g someone want to search Sara. if he enter SARA, SAra or sara. he should be able to get Sara. elastic search uses analyzer which makes everything lowercase.

I want to implement it case insensitive regardless of user input uppercase or lowercase name, he/she should get results. I am using ngram filter to search names and lowercase which makes it case insensitive. But I want to make sure that a person get results if even he enters in uppercase or lowercase.

Is there any way to do this in elastic search?

{"settings": {

        "analysis": {
            "filter": {
                "ngram_filter": {
                    "type": "ngram",
                    "min_gram": 1,
                    "max_gram": 80
                }
            },
            "analyzer": {
                "index_ngram": {
                    "type": "custom",
                    "tokenizer": "keyword",
                    "filter": [ "ngram_filter", "lowercase" ]
                },

I attach the example.js file which include json example and search.txt file to explain my problem . I hope my problem will be more clear now. this is the link to onedrive where I kept both files. https://1drv.ms/f/s!AsW4Pb3Y55Qjb34OtQI7qQotLzc

Answer 1

Is there any specific reason you are using ngram? Elasticsearch uses the same analyzer on the "query" as well as the text you index - unless search_analyzer is explicitly specified, as mentioned by @Adam in his answer. In your case it might be enough to use a standard tokenizer with a lowercase filter

I created an index with the following settings and mapping:

{
   "settings": {
      "analysis": {
         "analyzer": {
            "custom_analyzer": {
               "type": "custom",
               "tokenizer": "standard",
               "filter": [
                  "lowercase"
               ]
            }
         }
      }
   },
   "mappings": {
      "typehere": {
         "properties": {
            "name": {
               "type": "string",
               "analyzer": "custom_analyzer"
            },
            "description": {
               "type": "string",
               "analyzer": "custom_analyzer"
            }
         }
      }
   }
}

Indexed two documents Doc 1

PUT /test_index/test_mapping/1
    {
        "name" : "Sara Connor",
        "Description" : "My real name is Sarah Connor."
    }

Doc 2

PUT /test_index/test_mapping/2
    {
        "name" : "John Connor",
        "Description" : "I might save humanity someday."
    }

Do a simple search

POST /test_index/_search?query=sara
{
    "query" : {
        "match" : {
            "name" : "SARA"
        }
    }
}

And get back only the first document. I tried with "sara" and "Sara" also, same results.

{
  "took": 12,
  "timed_out": false,
  "_shards": {
    "total": 5,
    "successful": 5,
    "failed": 0
  },
  "hits": {
    "total": 1,
    "max_score": 0.19178301,
    "hits": [
      {
        "_index": "test_index",
        "_type": "test_mapping",
        "_id": "1",
        "_score": 0.19178301,
        "_source": {
          "name": "Sara Connor",
          "Description": "My real name is Sarah Connor."
        }
      }
    ]
  }
}