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

Question

I'm having issues trying to remove elements/objects from an array in elasticsearch.
This is the mapping for the index:
{
"example1": {
"mappings": {
"doc": {
"properties": {
"locations": {
"type": "geo_point"
},
"postDate": {
"type": "date"
},
"status": {
"type": "long"
},
"user": {
"type": "text",
"fields": {
"keyword": {
"type": "keyword",
"ignore_above": 256
}
}
}
}
}
}
}
}
And this is an example document.
{
"_index": "example1",
"_type": "doc",
"_id": "8036",
"_score": 1,
"_source": {
"user": "kimchy8036",
"postDate": "2009-11-15T13:12:00",
"locations": [
[
72.79887719999999,
21.193036000000003
],
[
-1.8262150000000001,
51.178881999999994
]
]
}
}
Using the query below, I can add multiple locations.
POST /example1/_update_by_query
{
"query": {
"match": {
"_id": "3"
}
},
"script": {
"lang": "painless",
"inline": "ctx._source.locations.add(params.newsupp)",
"params": {
"newsupp": [
-74.00,
41.12121
]
}
}
}
But I'm not able to remove array objects from locations. I have tried the query below but it's not working.
POST example1/doc/3/_update
{
"script": {
"lang": "painless",
"inline": "ctx._source.locations.remove(params.tag)",
"params": {
"tag": [
-74.00,
41.12121
]
}
}
}
Kindly let me know where i am doing wrong here. I am using elastic version 5.5.2

Answer 1

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"
}
}
}

Answer 2

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.

Answer 3

"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.