elasticsearch : search issue with accent in spite of french analyzer

Question

When i do a search without accent, i don't have a match with the same words which have an accent in spite of i set a french analyzer in mapping

This is my mapping:

PUT /test12h31
{
  "mappings": {
      "proj": {
        "properties": {
          "movieTitle": {
            "type": "text",
            "fields": {
             "keyword": {
                      "type": "keyword",
                      "ignore_above": 256
                    }
            },
            "analyzer": "french"
          }
        }
      }
    }
}

I enter data with:

 PUT /test12h31/proj/_search
    {
       "movieTitle":"Le Retour Du Héros"
    }

And i have no result when i do this search:

POST /test12h31/proj/_search
{
  "query": {
    "match": {
        "movieTitle": "hero"
    }
  }
}

When i replace "hero" by "héro" in my search request i have a result.

Could you help me to understand what happens and how to ignore accents please?

Answer 1

The french analyzer doesn't take care of accents, for that you need to include the asciifolding token filter.

I suggest you modify your index settings and mapping like this in order to redefine the french analyzer to include the asciifolding token filter:

PUT /test12h31
{
  "settings": {
    "analysis": {
      "filter": {
        "french_elision": {
          "type":         "elision",
          "articles_case": true,
          "articles": [
              "l", "m", "t", "qu", "n", "s",
              "j", "d", "c", "jusqu", "quoiqu",
              "lorsqu", "puisqu"
            ]
        },
        "french_stop": {
          "type":       "stop",
          "stopwords":  "_french_" 
        },
        "french_stemmer": {
          "type":       "stemmer",
          "language":   "light_french"
        }
      },
      "analyzer": {
        "french": {
          "tokenizer":  "standard",
          "filter": [
            "french_elision",
            "lowercase",
            "asciifolding",
            "french_stop",
            "french_stemmer"
          ]
        }
      }
    }
  },
      "mappings": {
          "proj": {
            "properties": {
              "movieTitle": {
                "type": "text",
                "fields": {
                 "keyword": {
                          "type": "keyword",
                          "ignore_above": 256
                        }
                },
                "analyzer": "french"
              }
            }
          }
        }
    }
}

Then you'll get results for your search.