Freemarker syntax for accessing item in array

ahoang

I am trying to create a custom payload for my Webhook destination. The input event payload has an array of items and I always want to access fields in the first item of the array. I am able to successfully test the connection if I only access the first item of the array, but when I try to access properties within that item, I get a configuration error.

 

"${input.events[0].event_type}"

Leads to the error below

There was an issue with sending your test event.<br />Invalid payload or configuration.

 

But 

"${input.events[0]}"

does not lead to any errors. This suggests that accessing the item using the index works correctly, but I can’t find any documentation out there on how to access the properties within that item.

 

For reference, this is the input event. I redacted some private information. This is an integration between RevenueCat and Amplitude, I need to forward some of this info to another service (Singular) which Amplitude does not have an integration for.

<br />{<br />  "api_key": <redacted>,<br />  "events": [<br />    {<br />      "event_properties": {<br />        "aliases": [<br />          <redacted><br />        ],<br />        "app_id": <redacted>,<br />        "app_user_id": <redacted>,<br />        "cancel_reason": "UNSUBSCRIBE",<br />        "currency": "USD",<br />        "entitlement_id": null,<br />        "entitlement_ids": [<br />          "Default"<br />        ],<br />        "environment": "SANDBOX",<br />        "expiration_at": "2023-11-30T17:02:04Z",<br />        "original_app_user_id": <redacted>,<br />        "original_transaction_id": <redacted>,<br />        "period_type": "NORMAL",<br />        "presented_offering_id": null,<br />        "product_id": <redacted>,<br />        "purchased_at": "2023-11-30T16:02:04Z",<br />        "revenue": 0,<br />        "store": "APP_STORE",<br />        "subscriber_attributes": {<br />          "$fbAnonId": <redacted>,<br />          "$idfa": <redacted>,<br />          "$idfv": <redacted>,<br />          "$ip": <redacted>,<br />          "$onesignalId": <redacted>,<br />          "$onesignalUserId": <redacted><br />        },<br />        "transaction_id": <redacted><br />      },<br />      "event_type": "cancellation_event",<br />      "insert_id": <redacted>,<br />      "partner_id": "revenuecat",<br />      "platform": "iOS",<br />      "productId": <redacted>,<br />      "revenue": 0,<br />      "time": 1701360394149,<br />      "user_id": <redacted>,<br />      "user_properties": {<br />        "rc_subscription_status": "cancelled"<br />      }<br />    }<br />  ],<br />  "options": {<br />    "min_id_length": 5<br />  }<br />}