Remove elements/objects From Array in ElasticSearch Followed by Matching Query

Unlike add(), remove() takes the index of the element and remove it.

Your ctx._source.locations in painless is an ArrayList. It has List's remove() method:

E remove(int index)

Removes the element at the specified position in this list (optional operation). ...

See Painless API - List for other methods.

See this answer for example code.

In painless scripts, Array.remove() method removes by index, not by value.

Here's a working example that removes array elements by value in Elasticsearch script:

POST objects/_update_by_query{    "query": {        ...  // use regular ES query to remove only in relevant documents    },    "script": {        "source": """            if (ctx._source[params.array_attribute] != null) {                for (int i=ctx._source[params.array_attribute].length-1; i>=0; i--) {                    if (ctx._source[params.array_attribute][i] == params.value_to_remove) {                        ctx._source[params.array_attribute].remove(i);                    }                }            }        """,        "params": {            "array_attribute": "<NAME_OF_ARRAY_PROPERTY_TO_REMOVE_VALUE_IN>",            "value_to_remove": "<VALUE_TO_REMOVE_FROM_ARRAY>",        }    }}

You might want to simplify script, if your script shall only remove values from one specific array attribute. For example, removing "green" from document's .color_list array:

_doc/001 = {    "color_list": ["red", "blue", "green"]}

Script to remove "green":

POST objects/_update_by_query{    "query": {        ...  // use regular ES query to remove only in relevant documents    },    "script": {        "source": """            for (int i=ctx._source.color_list.length-1; i>=0; i--) {                if (ctx._source.color_list[i] == params.color_to_remove) {                    ctx._source.color_list.remove(i);                }            }        """,        "params": {            "color_to_remove": "green"        }    }}

"script" : {    "lang":"painless",    "inline":"ctx._source.locations.remove(params.tag)",    "params":{      "tag":indexToRemove    }}

If with ctx._source.locations.add(elt) You add the element, with ctx._source.locations.remove(indexToRemove), you remove by the index of element in the array.