elasticsearch filtering by the size of a field that is an array

Question

How can I filter documents that have a field which is an array and has more than N elements?

How can I filter documents that have a field which is an empty array?

Answer 1

Still posting to here for who stuck same situation with me. Let's say your data look like this:

{
    "_source": {
        "fieldName" : [
            {
                "f1": "value 11",
                "f2": "value 21"
            },
            {
                "f1": "value 12",
                "f2": "value 22"
            }
        ]
    }
}

Then to filter fieldName with length > 1 for example:

"query": {
    "bool" : {
        "must" : {
            "script" : {
                "script" : {
                    "inline": "doc['fieldName.f1'].values.length > 1",
                    "lang": "painless"
                 }
            }
        }
    }
}

The script syntax is as ES 5.4 documentation https://www.elastic.co/guide/en/elasticsearch/reference/current/query-dsl-script-query.html.