Set JSON-Mode Expression Migrator to Safe Manual Mapping with Field-by-Field Verification

How it works

1. 1.Manual Trigger starts the run with a single empty item
2. 2.Code node declares the expression catalogue locally and evaluates each entry inside try/catch, producing canonical value, type and expectation
3. 3.Set node (manual mapping) writes migrationStatus plus string/number/boolean/object values with includeOtherFields:true
4. 4.IF node compares mappedValueText with expectedComparable using strict string equals
5. 5.True branch feeds Merge input 1; false branch passes through NoOp into Merge input 2
6. 6.Final Code node (runOnceForAllItems) returns exactly one migration report object

Use cases

• Safely migrating Set JSON-mode expressions to manual mapping
• Proving field-by-field value equivalence after rewriting expressions
• Testing expressions containing $, & or $& before production rollout
• Producing a migration quality report during code review

Requirements

• n8n 2.46.7 or newer
• No credentials and no network access required
• Edit the definitions array in the first Code node to insert your real expressions and expected values

Setup and testing in n8n

1. Import the JSON workflow into n8n
2. Click Execute Workflow and confirm the first Code node outputs seven items
3. Open the Set node and verify no JSON mode is used and types are correct
4. Inspect the report: 7 expressions, 5 matched, 2 mismatched, 1 evaluation error
5. Invalid cases: discountLabel differs from expectation and brokenRef fails evaluation; both appear in mismatches
6. Change the expected value of discountLabel to -10%&off and re-run to see 6 matched

Service Value

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