| `field` | yes | - | The field to insert, upsert, or update. Supports <<template-snippets,template snippets>>.
| `value` | yes* | - | The value to be set for the field. Supports <<template-snippets,template snippets>>. May specify only one of `value` or `copy_from`.
| `copy_from` | no | - | The origin field which will be copied to `field`, cannot set `value` simultaneously. Supported data types are `boolean`, `number`, `array`, `object`, `string`, `date`, etc.
| `override` | no | `true` | If processor will update fields with pre-existing non-null-valued field. When set to `false`, such fields will not be touched.
| `ignore_empty_value` | no | `false` | If `true` and `value` is a <<template-snippets,template snippet>> that evaluates to `null` or the empty string, the processor quietly exits without modifying the document
| `media_type` | no | `application/json` | The media type for encoding `value`. Applies only when `value` is a <<template-snippets,template snippet>>. Must be one of `application/json`, `text/plain`, or `application/x-www-form-urlencoded`.