Conditional JSON Patch

Javascript Object Notation (JSON) Patch is a JSON document structure for expressing a sequence of operations to apply to a JSON document. In some cases, it is desirable to conditionally apply a patch to a JSON data message payload based on the value of a given field in the document. The test operation can be used to conditionally apply a patch to a data message payload.

This example demonstrates using a test operation with the json-patch transformer to only apply a patch to payloads for a specific device. The device identifier is accessed by injecting it into the data message payload using the inject-metadata transformer. A subsequent json-patch step removes the metadata from the payload.

Pipeline: Conditional JSON Patch

filter:
  path: "*"
  content_type: application/json
steps:
  - name: get-metadata
    transformer:
      type: inject-metadata
      version: v1
  - name: conditional-patch
    transformer:
      type: json-patch
      version: v1
      parameters:
        patch: |
          [
            {"op": "test", "path": "/device_id", "value": "649998262fecb43eb2d39859"},
            {"op": "add", "path": "/demo", "value": true}
          ]
  - name: remove-metadata
    transformer:
      type: json-patch
      version: v1
      parameters:
        patch: |
          [
            {"op": "remove", "path": "/device_id"},
            {"op": "remove", "path": "/project_id"},
            {"op": "remove", "path": "/timestamp"}
          ]
  - name: send-lightdb
    destination:
      type: lightdb-stream
      version: v1