Serverless lambda function which handles validation, JSON parsing of request and error handling.

handler.js

'use strict';

import utilities from './../lib/utilities';
import ExampleObject from './../objects/ExampleObject';
import Ajv from 'ajv';

const schema = {
  "properties": {
    "primaryID": {
      "type": "string",
      "format": "uuid"
    }
  },
  "required": ["primaryID"]
};

module.exports.fetch = async function(event, context, callback) {
  if (event.source === 'serverless-plugin-warmup') {
    console.log('WarmUP - Lambda is warm!');
    return callback(null, 'Lambda is warm!');
  }
  
  try {
    const ajv = new Ajv();
    const query = utilities.parseJSON(event.query);
    const validate = ajv.compile(schema);
    const valid = validate(query);
    
    if(valid){
      let exampleObject = new ExampleObject(event);
      let response = await exampleObject.fetch();
      return callback(null, response);
    } else {
      return callback(
        new Error(
          "[400] ".concat(ajv.errorsText(validate.errors))
        )
      );
    }
  } catch(error) {
      console.error(error);
      return callback(new Error('[500] Internal Server Error'));
  }
};