Validator

Server Source code Package

Validates events using JSON Schema with two modes: format (structure of the full WalkerOS.Event) and contract (entity/action business rules). Invalid events are dropped from the pipeline and logged; valid events pass through unchanged.

Installation

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Integrated

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Bundled

Add to your flow.json:

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See bundled mode setup | CLI reference

Configuration

This transformer uses the standard transformer config wrapper (consent, data, env, id, ...). For the shared fields see transformer configuration. Package-specific fields live under config.settings and are listed below.

Settings

Property	Type	Description	More
format	boolean	Validate full WalkerOS.Event structure. Pre-compiled at init.
contract	object	Event-specific validation rules. Entity/action keyed, supports wildcards.

Mapping

This package does not define custom rule-level settings. For the standard rule fields (consent, condition, data, batch, name, policy) see mapping.

Examples

Contract validation

Contract validation passes when event data matches the entity.action JSON Schema

Event

Out

Valid event

A well-formed product view passes validation and is returned unchanged for downstream destinations.

Event

Out

Validation modes

Mode	Purpose
format	Validates full WalkerOS.Event structure
contract	Validates entity/action-specific business rules

Logger levels

Level	Output
ERROR	Validation failures only
DEBUG	All validation results (pass and fail)

Behavior

When validation fails

Invalid events are dropped from the pipeline and do not reach destinations. The validator logs detailed error information:

Validation	Log message	Includes
Format	Event format invalid	Field-level errors from AJV
Contract	Contract validation failed	Rule name + field-level errors

Example log output:

[ERROR] Event format invalid { errors: "data/name must match pattern \"^\\w+ \\w+$\"" }
[ERROR] Contract validation failed { rule: "product add", errors: "data must have required property 'id'" }

When validation passes

• Format valid: Event continues to contract validation (if configured)
• Contract valid: Logs debug message, event continues to next transformer or destinations
• No matching contract: Event passes through unchanged (validation is opt-in per entity/action)

Pipeline flow

Event → Format check → Contract check → Next transformer/Destination
             ↓                ↓
          Invalid?         Invalid?
             ↓                ↓
        Drop + Log       Drop + Log

Conditional rules

Apply different schemas based on event data:

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Wildcard patterns

Match multiple events with wildcards:

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Next steps

• Create your own - Build custom transformers