Retrieving data extension external key via Rest API

Question

Step 1 I am passing the Journey ID in the call to get the data extension ID

 Get
https://xxxxxxxx.rest.marketingcloudapis.com/interaction/v1/eventDefinitions/{5b3c1a00-0bbc-4484-b7be-21234567890}

Sample Response:

    {
"id": "xxxxx",
"type": "EmailAudience",
"name": "xxxxxx",
"description": "",
"createdDate": "2019-07-02T21:41:53.4",
"createdBy": 100169002,
"modifiedDate": "2019-07-02T21:41:53.4",
"modifiedBy": 100169002,
"mode": "Production",
"eventDefinitionKey": "DEAudience-xxxx",
"dataExtensionId": "xxxxxxx",
"dataExtensionName": "xxxxxxxxxx",
"sourceApplicationExtensionId": "xxxxx",
"filterDefinitionId": "00000000-0000-0000-0000-000000000000",
"filterDefinitionTemplate": "",
"iconUrl": "/images/icon-data-extension.svg",
"arguments":
Unknown macro: { "serializedObjectType"}
,
"configurationArguments":
Unknown macro: { "unconfigured"}
,
"metaData":
Unknown macro: { "criteriaDescription"}
,
"interactionCount": 1,
"isVisibleInPicker": false,
"isPlatformObject": false,
"category": "Audience",
"publishedInteractionCount": 1,
"automationId": "xxxxxxx"
}

Now I want to retrieve the External key for the data extension via rest API. Are there any sample calls to retrieve the External key based on the dataExtensionId got from the above response?

Answer 1

The REST and SOAP APIs do not have full parity at this stage. ( Source: https://developer.salesforce.com/docs/atlas.en-us.mc-apis.meta/mc-apis/index-api.htm ). Data Extensions go as "Most other email activities", filed under SOAP. (You can only deduce this as they aren't listed as one of the positive options for either REST or SOAP...)

So, unfortunately, for retrieving a key, you'd have to go for SOAP as of today. Using WS Proxy, SOAP feels a lot less cumbersome though. This example from the docs finds the CustomerKey for a DE:

https://developer.salesforce.com/docs/atlas.en-us.noversion.mc-programmatic-content.meta/mc-programmatic-content/ssjs_WSProxy_advanced_retrieve.htm