Painless Script to Update Array

[mrbarret (Matthew Barrett)]

I am using ELK 7.4.2 and need to write a script to update documents in my cluster. (We have about 20 TB of data so I also ask for advice about optimizations!)

I have documents that look like

{
   "owner": "Matt",
   "cars": [ "Honda", "Kia", "Aston Martin" ]
}

and I would like to write a script that will remove values from matching documents. For example, remove "Aston Martin" from all the cars array for all documents that have "Aston Martin" in the cars array. I have a number of attempts to do this but am having a hard time even debugging the problem(s). Any advice would be appreciated. Here is my latest attempt.

POST /automobiles/_update_by_query
{
  "query": {
    "term": {
         "cars": "Aston Martin"
    }
  },
  "script_fields": {
    "edit-automobiles-script": {
      "script": {
        "source": """
          def names = ["Aston Martin"];
           for (int j = 0; doc.containsKey("cars") && j < doc["cars"].size(); j++) {
                if (names.contains(doc["cars"][j])) {
                  doc["cars"].values.removeIf(car -> names.contains(car));
                }
            }
""",
        "lang": "painless"
      },
      "ignore_failure": false
    }
  }
}```