Nested JSON Undefined Path Diagnostics with Quarantine

How it works

1. 1.Run Manual Trigger; the injection Code node emits three fictional records matching the real input schema
2. 2.A Code node scans every mapped path depth-first, flagging undefined, null, "undefined" strings and missing keys
3. 3.Each bad output path is matched to its source path using the SPECS table with array index substitution
4. 4.An If node sends clean records (status=clean) to the true lane and corrupt ones to quarantine
5. 5.A Merge appends both branches and a final Code node builds one report with counts and issue details

Use cases

• Diagnosing undefined errors after transforming nested JSON payloads into a target structure
• Data quality gating before passing transformed output downstream
• Quarantining corrupt records with precise per-path source traceability

Requirements

• n8n 2.45.5 with Manual Trigger, Code, If, Merge, NoOp and Sticky Note nodes
• No credentials or network connections
• For real use: replace the injection node with your upstream items and update the SPECS table inside the scanner to match your mapping

Setup and testing in n8n

1. Import the JSON into n8n and execute Manual Trigger
2. Verify the Final Diagnostic Report: one clean record and two quarantined records
3. Add a record missing a mapped key to see the missing_output_key issue type
4. Test edge cases like empty arrays or null fields to confirm safe handling

Service Value

Ready-made workflow template for automation delivery and service execution.