How to get all field names in elasticsearch index

Question

I just start using elasticsearch 5.2 .

I am trying to get all keys in the index if I have the following mapping:

"properties": {
         "name": { "type": "text" },
         "article": {
          "properties": {
           "id": { "type": "text" },
           "title":  { "type": "text"},
           "abstract": { "type": "text"},
            "author": {
             "properties": {
              "id": { "type": "text" },
              "name": { "type": "text" }
}}}} } }

is it possible to get all fields full name ? like this:

 name,
 article.id ,
 article.title ,
 article.abstract ,
 article.author.id,
 article.author.name

how can I get that ?

Answer 1

You may use _field_names field.

The _field_names field indexes the names of every field in a document that contains any value other than null.

GET _search
{
  "size"0,
  "aggs": {
    "Field names": {
      "terms": {
        "field": "_field_names", 
        "size": 100
      }
    }
  }
}

Update : from ES 5 onwards

the _field_names field has been locked down and is only indexed, it doesn't support fielddata (memory intensive) or doc values,

Ref : https://github.com/elastic/elasticsearch/issues/22576

As an alternative, you may getMapping API

The get mapping API can be used to get more than one index or type mapping with a single call. General usage of the API follows the following syntax: host:port/{index}/_mapping/{type}

$ curl -XGET 'http://localhost:9200/index/_mapping?pretty'

You may then process the response to extract all the field names in the index