Elasticsearch - Updating nested fields

es-updating-nested-fields.txt

POST my-index/_update_by_query
{
	"script": {
		// "source" after v5.6, "inline" before
		"source": """
			for (item in ctx._source.nested_items) { 
				for(param in params.new_values) { 
					if (item.category == param.category) { 
						item.description = param.description; 
					} 
				} 
			}
		""",
		"lang": "painless",
		"params": {
			"new_values": [
				{
					"category": 1,
					"description": "Category 1 description"
				},
				{
					"category": 2,
					"description": "Category 2 description"
				},
				{
					"category": 3,
					"description": "Category 3 description"
				}
			]
		}
	},
	"query":{
		"term": {
			"_id": "1"
		}
	}
}