RevenueCat x Braze for user_alias drops external_id and breaks integration

[nsarno-lucid]

• I have updated Purchases SDK to the latest version
• I have read the Contribution Guidelines
• I have searched the Community
• I have read docs.revenuecat.com
• I have searched for existing Github issues

Describe the bug

The iOS SDK docs supports sending user_alias fields to Braze:
https://www.revenuecat.com/docs/integrations/third-party-integrations/braze

Purchases.shared.attribution.setAttributes(["$brazeAliasName": "name", "$brazeAliasLabel": "label"])

However, if we set this value, the external_id gets dropped from the payload when sending to Braze and then Braze does not recognize the event.

The following event sends to Braze from RevenueCat, but Braze fails to recognize it on their end:

{
  "events": [
    {
      "name": "revenueCat_trial_started_event",
      "time": "2025-01-22T18:48:17.000000",
      "properties": {
        "product_id": "abc123",
        "store": "STRIPE",
        "revenue": 0,
        "app_id": "abc123"
      },
      "user_alias": {
        "alias_name": "USERID",
        "alias_label": "currentUserId"
      }
    }
  ],
  "attributes": [
    {
      "user_alias": {
        "alias_name": "USERID",
        "alias_label": "currentUserId"
      },
      "rc_active_entitlements": [
        "entitlement"
      ],
      "rc_subscription_status": "trial"
    }
  ]
}

The following event is successfully recognized by Braze, but doesn't have a user_alias set:

{
  "events": [
    {
      "name": "revenueCat_trial_started_event",
      "time": "2025-01-23T19:24:46.000000",
      "properties": {
        "product_id": "abc123",
        "store": "STRIPE",
        "revenue": 0,
        "app_id": "abc123"
      },
      "external_id": "USERID"
    }
  ],
  "attributes": [
    {
      "external_id": "USERID",
      "rc_active_entitlements": [
        "entitlement"
      ],
      "rc_subscription_status": "trial"
    }
  ]
}

Per Braze docs, the example looks like we should be sending both values, external_id always and user_alias if it is available.
https://www.braze.com/docs/api/objects_filters/user_alias_object/#example

Are you able to update this or is the recommendation to not use user_alias?

[RCGitBot]

👀 We've just linked this issue to our internal tracker and notified the team. Thank you for reporting, we're checking this out!

[nsarno-lucid]

Update: It seems the behavior is for user_alias to take priority over external_id. If this is intended, it should be more clear in the docs. Currently it says the brazeAliasName is "optional" which sounds like an additional nice-to-have field and not a replacement of the original.

Closing this because we are reverting to not setting user_alias.