kuromoji_readingform token filter

The kuromoji_readingform token filter replaces the token with its reading form in either katakana or romaji. It accepts the following setting:

use_romaji
Whether romaji reading form should be output instead of katakana. Defaults to false.

When using the pre-defined kuromoji_readingform filter, use_romaji is set to true. The default when defining a custom kuromoji_readingform, however, is false. The only reason to use the custom form is if you need the katakana reading form:

PUT kuromoji_sample
{
    "settings": {
        "index":{
            "analysis":{
                "analyzer" : {
                    "romaji_analyzer" : {
                        "tokenizer" : "kuromoji_tokenizer",
                        "filter" : ["romaji_readingform"]
                    },
                    "katakana_analyzer" : {
                        "tokenizer" : "kuromoji_tokenizer",
                        "filter" : ["katakana_readingform"]
                    }
                },
                "filter" : {
                    "romaji_readingform" : {
                        "type" : "kuromoji_readingform",
                        "use_romaji" : true
                    },
                    "katakana_readingform" : {
                        "type" : "kuromoji_readingform",
                        "use_romaji" : false
                    }
                }
            }
        }
    }
}

POST kuromoji_sample/_analyze?analyzer=katakana_analyzer&text=寿司 

POST kuromoji_sample/_analyze?analyzer=romaji_analyzer&text=寿司 

Returns スシ.

Returns sushi.