[BUG]: external_customer_id is always received as null

[rawwerks]

Describe the bug
The value of external_customer_id is not being received by Lago via the events API, it is always null.

To Reproduce

curl --location --request POST "https://localhost:3000/api/v1/events" \
  --header "Authorization: Bearer my-key" \
  --header 'Content-Type: application/json' \
  --data-raw '{
    "event": {
      "transaction_id": "test00001",
      "external_customer_id": "placeholder",
      "code": "test-curl",
      "properties": {
          "cost": "1"
      }
    }
}'

Expected behavior
The external_customer_id should be equal to "placeholder", instead it is null:

{
  "event": {
    "transaction_id": "test00001",
    "external_customer_id": null,
    "external_subscription_id": null,
    "code": "test-curl",
    "timestamp": 1725407284,
    "properties": {
      "cost": "1"
    }
  }
}

Additional context
here is the return, in case helpful:

{"event":{"lago_id":"ada83cb6-8d95-4a1e-b1dc-089dd0a365c1","transaction_id":"test00001","lago_customer_id":null,"code":"test-curl","timestamp":"2024-09-03T23:48:04.258Z","properties":{"cost":"1"},"lago_subscription_id":null,"external_subscription_id":null,"created_at":"2024-09-03T23:48:05Z"}}%   

related: BerriAI/litellm#5477

[rawwerks]

oh wait...this is a new change: https://docs.getlago.com/guide/migration/migration-to-v1.2.0#2-mandatory-external-subscription-id-field-in-event-payloads

so can you explain what an external_subscription_id is supposed to be?

[rawwerks]

even with this field, the external_customer_id is still null:

curl --location --request POST "https://localhost:3000/api/v1/events" \
  --header "Authorization: Bearer my-key" \
  --header 'Content-Type: application/json' \
  --data-raw '{
    "event": {
      "transaction_id": "test00002",
      "external_customer_id": "placeholder",
      "external_subscription_id": "wtf is this supposed to be?",
      "code": "test-curl",
      "properties": {
          "cost": "1"
      }
    }
}'

shows payload:

{
  "event": {
    "transaction_id": "test00002",
    "external_customer_id": null,
    "external_subscription_id": "wtf is this supposed to be?",
    "code": "test-curl",
    "timestamp": 1725407985,
    "properties": {
      "cost": "1"
    }
  }
}

and returns:

{"event":{"lago_id":"56b51d8a-4886-4347-a369-afb9038d6791","transaction_id":"test00002","lago_customer_id":null,"code":"test-curl","timestamp":"2024-09-03T23:59:45.499Z","properties":{"cost":"1"},"lago_subscription_id":null,"external_subscription_id":"wtf is this supposed to be?","created_at":"2024-09-03T23:59:45Z"}}%   

[rawwerks]

external_customer_id is apparently deprecated now:
https://lago-community.slack.com/archives/C03MCH55EL8/p1725408699599749?thread_ts=1725407568.186619&cid=C03MCH55EL8

[jdenquin]

@rawwerks yes this field is not used anymore and not supported, the source of truth is now external_subscription_id