Update documents using scripts

You can use the update API to update documents with a specified script. The script can update, delete, or skip modifying the document. The update API also supports passing a partial document, which is merged into the existing document.

First, let’s index a simple document:

PUT my-index-000001/_doc/1
{
  "counter" : 1,
  "tags" : ["red"]
}

To increment the counter, you can submit an update request with the following script:

POST my-index-000001/_update/1
{
  "script" : {
    "source": "ctx._source.counter += params.count",
    "lang": "painless",
    "params" : {
      "count" : 4
    }
  }
}

Similarly, you can use an update script to add a tag to the list of tags. Because this is just a list, the tag is added even it exists:

POST my-index-000001/_update/1
{
  "script": {
    "source": "ctx._source.tags.add(params['tag'])",
    "lang": "painless",
    "params": {
      "tag": "blue"
    }
  }
}

You can also remove a tag from the list of tags. The remove method of a Java List is available in Painless. It takes the index of the element you want to remove. To avoid a possible runtime error, you first need to make sure the tag exists. If the list contains duplicates of the tag, this script just removes one occurrence.

POST my-index-000001/_update/1
{
  "script": {
    "source": "if (ctx._source.tags.contains(params['tag'])) { ctx._source.tags.remove(ctx._source.tags.indexOf(params['tag'])) }",
    "lang": "painless",
    "params": {
      "tag": "blue"
    }
  }
}

You can also add and remove fields from a document. For example, this script adds the field new_field:

POST my-index-000001/_update/1
{
  "script" : "ctx._source.new_field = 'value_of_new_field'"
}

Conversely, this script removes the field new_field:

POST my-index-000001/_update/1
{
  "script" : "ctx._source.remove('new_field')"
}

Instead of updating the document, you can also change the operation that is executed from within the script. For example, this request deletes the document if the tags field contains green. Otherwise it does nothing (noop):

POST my-index-000001/_update/1
{
  "script": {
    "source": "if (ctx._source.tags.contains(params['tag'])) { ctx.op = 'delete' } else { ctx.op = 'none' }",
    "lang": "painless",
    "params": {
      "tag": "green"
    }
  }
}