Data Validation

Validate input data before continuing the workflow

Overview

The Data Validation node is designed to validate incoming data against a user-defined JSON Schema before allowing the workflow to continue. This ensures that only data conforming to specific structural and type requirements proceeds further in your n8n automation. Common scenarios include:

  • Ensuring API responses or webhook payloads match expected formats.
  • Validating user input before processing or storing it.
  • Enforcing data integrity when integrating with external systems.

Practical Example:
If you expect each item to have an integer field foo and a string field bar, you can define this schema, and the node will halt execution (with an error) if any item does not comply.

Properties

Display Name Type Description
JSON Schema json The JSON Schema definition used for validation. Visit ajv.js.org or json-schema.org to learn how to describe your validation rules in JSON Schemas.

Details:

  • The property expects a valid JSON Schema as a string.
  • The default schema requires an object with:
    • An integer property foo (required).
    • A string property bar.
    • No additional properties allowed.

Output

  • json: Each output item contains the original input json object, unchanged, but only if it passed validation.
  • If any input item fails validation, the node throws an error and stops processing further items.
  • No binary data is produced by this node.

Example Output:

[
  {
    "json": {
      "foo": 123,
      "bar": "example"
    }
  }
]

Dependencies

  • External Library: ajv is used internally for JSON Schema validation.
  • No external services or API keys are required.

Troubleshooting

Common Issues:

  • Invalid JSON Schema:

    • Error: "Invalid JSON Schema"
    • Cause: The provided schema is not valid JSON or does not conform to JSON Schema standards.
    • Solution: Double-check your schema syntax and structure using online tools like JSON Schema Validator.

  • Validation Errors:

    • Error: "Invalid data" with details about which fields failed validation.
    • Cause: Input data does not match the defined schema (e.g., missing required fields, wrong types).
    • Solution: Review the error message for specifics and adjust your input data or schema accordingly.

  • Type Mismatch:

    • If the input data has types that do not match the schema (e.g., string instead of integer), validation will fail.

Links and References

Discussion