ElasticSearch - Append to integer array

Question

I am new to ES and but I'm getting the hang of it. It's a really powerful piece of software, but I have to say that the documentation is really lacking and confusing some times.

Here's my question: I have an integer array, that looks like this:

"hits_history" : [0,0]

I want to append an integer to that array via an "update_by_query" call, I searched and found this link: https://www.elastic.co/guide/en/elasticsearch/reference/current/docs-update.html which has this example:

POST test/type1/1/_update
{
    "script" : {
        "inline": "ctx._source.tags.add(params.tag)",
        "lang": "painless",
        "params" : {
            "tag" : "blue"
        }
    }
}

so I tried:

 curl -XPOST 'localhost:9200/example/example/_update_by_query?pretty' -H 'Content-Type: application/json' -d'
     {
       "script": {
         "inline": "ctx._source.hits_history.add(params.hits)",
         "params": {"hits": 0}
       },
       "query": {
        "match_all": {}
        }
     }
     '

but it gave me this error:

 "ctx._source.hits_history.add(params.hits); ",
 "                                   ^---- HERE"
 "type" : "script_exception",
     "reason" : "runtime error",
     "caused_by" : {
       "type" : "illegal_argument_exception",
       "reason" : "Unable to find dynamic method [add] with [1] arguments for class [java.lang.Integer]."

So, I looked further and found this: https://www.elastic.co/guide/en/elasticsearch/guide/current/partial-updates.html

which has this example:

We can also use a script to add a new tag to the tags array.

 POST /website/blog/1/_update
 {
    "script" : "ctx._source.tags+=new_tag",
    "params" : {
       "new_tag" : "search"
    }
 }

So I tried it:

 curl -XPOST 'localhost:9200/example/example/_update_by_query?pretty' -H 'Content-Type: application/json' -d'
 {
   "script": {
     "inline": "ctx._source.hits_history += 0;"
   },
   "query": {
    "match_all": {}
    }
 }
 '

Result:

 "type" : "script_exception",
     "reason" : "runtime error",
     "caused_by" : {
       "type" : "class_cast_exception",
       "reason" : "Cannot apply [+] operation to types [java.util.ArrayList] and [java.lang.Integer]."

So, how can I append items to the arrayList? Is there a more up-to-date documentation I should look into?

What I wanted to do was simply something like this: ctx._source.hits_history.add(ctx._source.today_hits); ctx._source.today_hits = 0;

Thank you

Answer 1

You should store first value as array (containing one value). Then you can use add() method.

POST /website/blog/1/_update
{
   "script" : "if (ctx._source.containsKey('tags')) { ctx._source.tags.add('next') } else { ctx._source.tags = ['first'] }"
}