merge

Last updated: Feb 24, 2026

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IMPLEMENTATION

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Definition

In a config modifier schema, use merge to avoid overwriting all of the properties of an output. This keyword combines multiple objects into one. If objects share the same property name, the value from the last object overwrites the first one.

Exclusive keywords

If properties, if, concat, switch, pipe, merge, prefer, or items are present at the same nesting level, only the first keyword listed will run. We recommend not listing these keywords together at the same nesting level.

Order of execution

This keyword executes in the following order:

omit
constant
references
use
get
Mutually exclusive keywords at this level:
- properties
- if
- concat
- switch
- pipe
- merge
- prefer
- items
default
plugin

Example

You could duplicate the Location resource's name to the description field.

Example: Merge input from initial payload

json

1
"resource": {
2
        "description": "Point of Care",
3
        "mode": "kind",
4
        "name": "USC-IS",
5
        "partOf": {
6
          "reference": "urn:uuid:8041c338-e0d8-4f60-a658-93d89e86f224"
7
        },
8
        "physicalType": {
9
          "coding": [
10
            {
11
              "code": "wa",
12
              "display": "Ward",
13
              "system": "http://terminology.hl7.org/CodeSystem/location-physical-type"
14
            }
15
          ],
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          "text": "wa"
17
        }
18
  }

Example: Merge selector

json

1
$.entry[?(@.resource.resourceType=="Location")].resource

Example: Config modifier with merge keyword

yaml

1
merge:
2
  - {}
3
  - properties:
4
      description:
5
        get: name

Example: Merge output

json

1
"resource": {
2
        "description": "USC-IS",
3
        "mode": "kind",
4
        "name": "USC-IS",
5
        "partOf": {
6
          "reference": "urn:uuid:8041c338-e0d8-4f60-a658-93d89e86f224"
7
        },
8
        "physicalType": {
9
          "coding": [
10
            {
11
              "code": "wa",
12
              "display": "Ward",
13
              "system": "http://terminology.hl7.org/CodeSystem/location-physical-type"
14
            }
15
          ],
16
          "text": "wa"
17
        }
18
 }

Alternative solution with @parent

To achieve the same outcome with the use keyword and @parent variable, try this selector and config modifier instead:

Example: Alternative selector

json

1
$.entry[?(@.resource.resourceType=="Location")].resource.description

Example: Alternative config modifier

yaml

1
use: '@parent'
2
get: name

Learn more about use and parent.

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