Schema Validator Node

The schema validator node validates incoming message data against a JSON Schema (draft 4/7). If validation fails the pipeline stops and no broadcast is emitted.

When to Use

• Enforce a strict contract on client-sent messages
• Reject malformed payloads early in the flow
• Prevent downstream nodes from receiving unexpected data shapes

Configuration

target values

Examples

Require specific fields in the payload

{
  "schema": {
    "type": "object",
    "required": ["userId", "text"],
    "properties": {
      "userId": { "type": "string" },
      "text":   { "type": "string", "maxLength": 500 }
    }
  }
}

Validate a numeric amount with constraints

{
  "schema": {
    "type": "object",
    "required": ["amount", "currency"],
    "properties": {
      "amount":   { "type": "number", "minimum": 0 },
      "currency": { "type": "string", "enum": ["USD", "EUR", "GBP"] }
    }
  }
}

Validate metadata only

{
  "schema": {
    "type": "object",
    "required": ["appId"],
    "properties": {
      "appId": { "type": "string" }
    }
  },
  "target": "metadata"
}

Supported JSON Schema Keywords

Full JSON Schema draft 4/7 is supported, including:

• type, enum, const
• required, properties, additionalProperties
• minLength, maxLength, pattern
• minimum, maximum, exclusiveMinimum, exclusiveMaximum
• minItems, maxItems, items, uniqueItems
• allOf, anyOf, oneOf, not
• $ref (within the same schema document)

On Failure

Validation errors are collected and returned as a human-readable string:

Schema validation failed on data: #/userId: Expected type string, got null, #/amount: Value must be >= 0

The pipeline stops; no downstream nodes run and no broadcast is emitted.

Next Steps

• Filter Node — filter using MongoDB-style query operators
• Transform Node — reshape data after validation