Debugging

Logs

All custom channel pipelines log to procpiper.log. For debugging, it is useful to add Log pipes at key points in the pipeline — before and after HTTP requests, after unpacking the response, before registering events.

Example: logging around an HTTP request

[
  {
    "id": 1,
    "type": "log",
    "params": {
      "message": "[Request] URL: $sender.url, method: POST",
      "level": "debug"
    },
    "outs": {
      "success": 2
    }
  },
  {
    "id": 2,
    "type": "http_request",
    "params": {
      "method": "POST",
      "timeout": 10,
      "content_type": "json",
      "url": "$sender.url",
      "success_codes": [200]
    },
    "outs": {
      "success": 3,
      "error": 5
    }
  },
  {
    "id": 3,
    "type": "unpack",
    "outs": {
      "success": 4,
      "error": 5
    }
  },
  {
    "id": 4,
    "type": "log",
    "params": {
      "message": "[Response] status: $in.data.status",
      "level": "debug"
    }
  },
  {
    "id": 5,
    "type": "log",
    "params": {
      "message": "[Error] code: $error.code, message: $error.message",
      "level": "error"
    }
  }
]

Error data

When any pipe encounters an error, the following variables are available:

Variable	Description
$error.code	Error code (number). Not all pipes return a code — see the table below
$error.message	Text description of the error. Available for all pipes

Error structure by pipe

Pipe	$error.code	$error.message
HTTP Request	Yes (HTTP code: 400, 403, 500, etc.)	Yes (error description: timeout, connection refused, etc.)
Pack	No	Yes (template error description)
Unpack	No	Yes (unmarshalling error description)
SQL	No	Yes (SQL error description)
Eventer	No	Yes (template or format error description)
Scheduler	No	Yes (template error description)
Selector	No	Yes (JsonQL error description)
Store Set / Store Get	No	Yes (database error description)
Log	No	Yes (template error description)
Result	No	Yes (path error or missing data description)
Error	No	Yes (message template error description)

Use them in Log, Eventer, or Error pipes for diagnostics.

Typical errors

SQL: forgot map: true in Read operation

Symptom: Result fails with a data type error. Cause: Without map: true, SQL returns an array []map[string]interface{}, but Result expects an object map[string]interface{}. Solution: Add "map": true to the SQL pipe parameters for the Read operation.

Templating: $ instead of $#

Symptom: A numeric field arrived as a string, the external API returned a validation error. Cause: The $ prefix always returns a string. The $# prefix preserves the original type. Solution: Use $# for numbers, booleans, arrays, and objects. For example, $#template.discountAmount instead of $template.discountAmount.

Scheduler: did not pass send_message_id in template

Symptom: Eventer in the Schedule pipeline cannot register an event — $origin.send_message_id is missing. Cause: In Schedule, $origin is replaced with params.template of the Scheduler pipe. Solution: Pass send_message_id explicitly through the template:

{
  "template": {
    "send_message_id": "$origin.send_message_id",
    "external_id": "$#in.data.externalId"
  }
}

And access it in Schedule as $origin.send_message_id.

HTTP Request: missing Pack before content_type: json

Symptom: Error $in.body not found.
Cause: content_type: json reads the body from $in.body, which is formed by the Pack pipe.
Solution: Add a Pack pipe before HTTP Request in the chain.

HTTP Request: $in.body is not a byte array

Symptom: Data type error for $in.body.
Cause: Pack pipe is not configured or type is not specified.
Solution: Make sure the Pack pipe has "type": "JSON" (or "XML") and is placed before HTTP Request.

Eventer: incorrect channel_id / action_type

Symptom: Event does not appear in reports and profile history.
Cause: channel_id does not match the numeric ID of the channel, action_type does not match the Event ID of the created event.
Solution: Verify the correspondence in the Events section of the channel: action_type = Event ID of the event.

Selector: error in JsonQL

Symptom: Event goes to outs.error of the Selector pipe.
Cause: Incorrect JsonQL query syntax or field not found.
Solution: Check the query syntax and make sure the field exists in $in or $template.

Channel verification after creation

1. Create a template with minimal content
2. Create a sender and a subscription (or a resource for indirect)
3. Send a test mailing
4. Check procpiper.log — entries from Log pipes should appear
5. Check events in profile history — a send or undeliv event should appear
6. If there is an error — add Log pipes before and after the problematic pipe to localize the failure point