Processors - Join - 《Elasticsearch v7.9 Reference》

Join processor

Joins each element of an array into a single string using a separator character between each element. Throws an error when the field is not an array.

Table 24. Join Options

Name	Required	Default	Description
`field`	yes	-	Field containing array values to join
`separator`	yes	-	The separator character
`target_field`	no	`field`	The field to assign the joined value to, by default `field` is updated in-place
`if`	no	-	Conditionally execute this processor.
`on_failure`	no	-	Handle failures for this processor. See Handling Failures in Pipelines.
`ignore_failure`	no	`false`	Ignore failures for this processor. See Handling Failures in Pipelines.
`tag`	no	-	An identifier for this processor. Useful for debugging and metrics.

{
  "join": {
    "field": "joined_array_field",
    "separator": "-"
  }
}