Schema Validation

Nodes can define JSON Schema for input and output validation. Validation runs automatically during workflow execution.

Schema helpers

import { Schema } from 'light-process';

Schema.string()                  // { type: 'string' }
Schema.string({ minLength: 1 }) // { type: 'string', minLength: 1 }
Schema.number()                  // { type: 'number' }
Schema.number({ minimum: 0 })   // { type: 'number', minimum: 0 }
Schema.integer()                 // { type: 'integer' }
Schema.boolean()                 // { type: 'boolean' }
Schema.array(Schema.string())   // { type: 'array', items: { type: 'string' } }
Schema.object(props, required)   // { type: 'object', properties, required }

Define on a node

SDK

node.inputs = Schema.object({
  name: Schema.string({ minLength: 1 }),
  age: Schema.integer({ minimum: 0, maximum: 150 }),
  tags: Schema.array(Schema.string(), { minItems: 1 }),
  active: Schema.boolean(),
}, ['name', 'age']); // required fields

node.outputs = Schema.object({
  result: Schema.string(),
  score: Schema.number({ minimum: 0, maximum: 100 }),
});

.node.json

{
  "inputs": {
    "type": "object",
    "properties": {
      "name": { "type": "string", "minLength": 1 },
      "age": { "type": "integer", "minimum": 0 }
    },
    "required": ["name", "age"]
  },
  "outputs": {
    "type": "object",
    "properties": {
      "result": { "type": "string" }
    }
  }
}

Validation behavior

Input validation runs before the node executes
Output validation runs after the node completes (only if successful)
If validation fails, the node result is marked as failed with the error details
If inputs or outputs is null, validation is skipped

Supported JSON Schema properties

Property	Applies to	Description
`type`	all	"string", "number", "integer", "boolean", "array", "object"
`properties`	object	Field definitions
`required`	object	Required field names
`items`	array	Item schema
`minItems`	array	Minimum array length
`maxItems`	array	Maximum array length
`minimum`	number/integer	Minimum value
`maximum`	number/integer	Maximum value
`minLength`	string	Minimum string length
`maxLength`	string	Maximum string length
`pattern`	string	Regex pattern
`enum`	all	Allowed values
`default`	all	Default value
`description`	all	Human-readable description

Error format

Validation errors include the field path:

Input validation failed: input.name: must NOT have fewer than 1 characters
Output validation failed: output.score: must be >= 0

Manual validation

import { validate, validateInput, validateOutput } from 'light-process';

const schema = Schema.object({
  name: Schema.string({ minLength: 1 }),
}, ['name']);

const result = validateInput({ name: '' }, schema);
// { valid: false, errors: ['input.name: must NOT have fewer than 1 characters'] }

const result2 = validateInput({ name: 'Alice' }, schema);
// { valid: true, errors: [] }

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