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Event Validation Middleware for Middy

Joi powered event validation middleware for Middy.

The middleware integrates Joi validation library to validate AWS Lambda events triggered by API Gateway.

Failed validations throw error of http-errors instance with status code 422.

Usage

import middy from 'middy';
import eventValidator from '@keboola/middy-event-validator';
 
export const handler = middy(() => {
  // ...
});
 
handler
  .use(eventValidator({
    path: {
      id: Joi.string().required()
    },
    body: {
      size: Joi.number().integer()
    },
    pagination: true
  }));

The configuration accepts following options:

• headers - validation of HTTP headers
• body - validation of HTTP body in JSON format
• path - validation of path parameters (shortcut for API Gateway's pathParameters)
• query - validation of query string (shortcut for API Gateway's queryStringParameters)
• pagination: true - shortcut for two query string parameters offset and limit validated as numbers.
  • Default and maximum for limit is 1000. It can be changed by a definition: pagination: { max: 10 }

The module also offers a set of validation shortcuts using class Validation:

import middy from 'middy';
import eventValidator, { Validation } from '@keboola/middy-event-validator';
 
handler
  .use(eventValidator({
    path: {
      id: Validation.string('id').required()
    }
  }));

List of available shortcuts:

• getJoi() - returns Joi instance for custom validation
• forbidden(param) - setting of the parameter is forbidden
• boolean(param) - boolean value
• string(param) - string. All string shortcuts promote trimming of trailing white spaces
• stringMaxLength(param, length) - string with maximal length
• integer(param)
• object(param)
• enum(param, values)
• array(param)
• arrayOfStrings(param)

All shortcuts create optional parameters, for required parameters add .required().