Validation

Moleculer has a built-in validator module. It uses the fastest-validator library.

Built-in validator

const { ServiceBroker } = require("moleculer");

const broker = new ServiceBroker({
    validation: true // Default is true
});

broker.createService({
    name: "say",
    actions: {
        hello: {
            // Parameters definitions to validator
            params: {
                name: { type: "string", min: 2 }
            },
            handler(ctx) {
                return "Hello " + ctx.params.name;
            }
        }
    }
});

broker.call("say.hello").then(console.log)
    .catch(err => console.error(err.message));
// -> throw ValidationError: "The 'name' field is required!"

broker.call("say.hello", { name: 123 }).then(console.log)
    .catch(err => console.error(err.message));
// -> throw ValidationError: "The 'name' field must be a string!"

broker.call("say.hello", { name: "Walter" }).then(console.log)
    .catch(err => console.error(err.message));
// -> "Hello Walter"

Play it on Runkit

Example validation schema

{
    id: { type: "number", positive: true, integer: true },
    name: { type: "string", min: 3, max: 255 },
    status: "boolean" // short-hand def
}

Documentation

You can find more information about validation schema in the documentation of the library

Custom validator

You can create your custom validator. You should implement compile and validate methods of BaseValidator.

Example for Joi

// --- JOI VALIDATOR CLASS ---

const BaseValidator = require("moleculer").Validator;
const { ValidationError } = require("moleculer").Errors;

class JoiValidator extends BaseValidator {
    constructor() {
        super();
        this.validator = require("joi");
    }

    compile(schema) {
        return (params) => this.validate(params, schema);
    }

    validate(params, schema) {
        const res = this.validator.validate(params, schema);
        if (res.error)
            throw new ValidationError(res.error.message, null, res.error.details);

        return true;
    }
}

// --- BROKER ---

const { ServiceBroker } = require("moleculer");
const Joi = require("joi");

const broker = new ServiceBroker({
    logger: true,
    validation: true,
    validator: new JoiValidator()
});

// --- SERVICE ---
broker.createService({
    name: "greeter",
    actions: {
        hello: {
            params: Joi.object().keys({
                name: Joi.string().min(4).max(30).required()
            }),
            handler(ctx) {
                return `Hello ${ctx.params.name}`;
            }
        }
    }
});

// --- TEST ---
broker.start()
    .then(() => broker.call("greeter.hello").then(res => broker.logger.info(res)))
    .catch(err => broker.logger.error(err.message, err.data))

    .then(() => broker.call("greeter.hello", { name: 100 }).then(res => broker.logger.info(res)))
    .catch(err => broker.logger.error(err.message, err.data))

    .then(() => broker.call("greeter.hello", { name: "Joe" }).then(res => broker.logger.info(res)))
    .catch(err => broker.logger.error(err.message, err.data))

    .then(() => broker.call("greeter.hello", { name: "John" }).then(res => broker.logger.info(res)))
    .catch(err => broker.logger.error(err.message, err.data));