How do I get the size of a 'nested' type array through a Painless script in Elasticsearch version 6.7? - elasticsearch

Question

I am using Elasticsearch version 6.7. I have the following mapping:
{
"customers": {
"mappings": {
"customer": {
"properties": {
"name": {
"type": "keyword"
},
"permissions": {
"type": "nested",
"properties": {
"entityId": {
"type": "keyword"
},
"entityType": {
"type": "keyword"
},
"permission": {
"type": "keyword"
},
"permissionLevel": {
"type": "keyword"
},
"userId": {
"type": "keyword"
}
}
}
}
}
}
}
}
I want to run a query to that shows all customers who have > 0 permissions. I have tried the following:
{
"query": {
"bool": {
"filter": {
"script": {
"script": {
"lang": "painless",
"source": "params._source != null && params._source.permissions != null && params._source.permissions.size() > 0"
}
}
}
}
}
}
But this returns no hits because params._source is null as Painless does not have access to the _source document according to this Stackoverflow post. How can I write a Painless script that gives me all customers who have > 0 permissions?

Answer 1

Solution 1: Using Script with must query
POST <your_index_name>/_search
{
"query": {
"bool": {
"must": [
{
"script": {
"script": {
"lang": "painless",
"inline": """
ArrayList st = params._source.permissions;
if(st!=null && st.size()>0)
return true;
"""
}
}
}
]
}
}
}
Solution 2: Using Exists Query on nested fields
You could simply make use of Exists query something like the below to get customers who have > 0 permissions.
Query:
POST <your_index_name>/_search
{
"query": {
"bool": {
"must": [
{
"nested": {
"path": "permissions",
"query": {
"bool": {
"should": [
{
"exists":{
"field": "permissions.permission"
}
},
{
"exists":{
"field": "permissions.entityId"
}
},
{
"exists":{
"field": "permissions.entityType"
}
},
{
"exists":{
"field": "permissions.permissionLevel"
}
}
]
}
}
}
}]
}
}
}
Solution 3: Create definitive structure but add empty values to the fields
Another alternative would be to ensure all documents would have the fields.
Basically,
Ensure that all the documents would have the permissions nested document
However for those who would not have the permissions, just set the field permissions.permission to 0
Construct a query that could help you get such documents accordingly
Below would be a sample document for a user who doesn't have permissions:
POST mycustomers/customer/1
{
"name": "john doe",
"permissions": [
{
"entityId" : "null",
"entityType": "null",
"permissionLevel": 0,
"permission": 0
}
]
}
The query in that case would be as simple as this:
POST <your_index_name>/_search
{
"query": {
"bool": {
"must": [
{
"nested": {
"path": "permissions",
"query": {
"range": {
"permissions.permission": {
"gte": 1
}
}
}
}
}
]
}
}
}
Hope this helps!