_meta field

A mapping type can have custom meta data associated with it. These are not used at all by Elasticsearch, but can be used to store application-specific metadata, such as the class that a document belongs to:

PUT my-index-000001
{
  "mappings": {
    "_meta": { 
      "class": "MyApp::User",
      "version": {
        "min": "1.0",
        "max": "1.3"
      }
    }
  }
}

The _meta field can be updated on an existing type using the update mapping API:

response = client.indices.put_mapping(
  index: 'my-index-000001',
  body: {
    _meta: {
      class: 'MyApp2::User3',
      version: {
        min: '1.3',
        max: '1.5'
      }
    }
  }
)
puts response

PUT my-index-000001/_mapping
{
  "_meta": {
    "class": "MyApp2::User3",
    "version": {
      "min": "1.3",
      "max": "1.5"
    }
  }
}