Elasticsearch painless, how to determine the data type of a field

Question

In es5.5, how to determine whether a field is numeric?

if (is_numeric(ctx._source.some)) {
    ctx._source.some = ctx._source.some + 2
}

Answer 1

The instanceof operator might help here

if (ctx._source.some instanceof byte ||
    ctx._source.some instanceof short ||
    ctx._source.some instanceof int ||
    ctx._source.some instanceof long ||
    ctx._source.some instanceof float ||
    ctx._source.some instanceof double)
{
    ctx._source.some = ctx._source.some + 2
}

Answer 2

Another approach is to use Debug.explain, see https://www.elastic.co/guide/en/elasticsearch/painless/6.8/painless-debugging.html

This will abort with a painless_explain_error and the output will tell you what classes are involved. With that information (obtained manually from your various indices across your various ElasticSearch versions), you can then implement Painless with instanceof, as shown in @oleg-grishko 's answer.

POST /hockey/player/1/_explain
{
  "query": {
    "script": {
       "script": "Debug.explain(doc.goals)"
    }
  }
}

{
   "error": {
      "type": "script_exception",
      "painless_class": "org.elasticsearch.index.fielddata.ScriptDocValues.Longs",
       ...