old_contents: // RethinkDB
  import r from 'rethinkdb';
  // Constants
  import { DB_HOST, DB_PORT } from '../../constants/configurations.js';
  import moment from 'moment';
  
  // create a worklog
  export async function createWorkLog(worklog){
  	let connection = null,
  		query = null;
  
  	try {
  		
  		worklog.create_date = moment().utc().format('X') * 1000;
  		query = r.db('work_genius').table('worklog').insert(worklog);
  		connection = await r.connect({ host: DB_HOST, port: DB_PORT });
  		let result = await query.run(connection);
  		await connection.close();
  		let id = '';
          if (result && result.generated_keys && result.generated_keys.length > 0){
            id = result.generated_keys[0];
          }
          return id;
  	} catch (err) {
  		return 'Fail to create a worklog!';
  	}
  };
  
  //update a worklog
  export async function updateWorkLog(id, worklog){
  	let connection = null,
  		query = null;
  
  	try {
  		
  		if(worklog.id){
  			delete worklog.id;
  		}
  		worklog.update_date = moment().utc().format('X') * 1000;
  		query = r.db('work_genius').table('worklog').get(id).update(worklog);
  		connection = await r.connect({ host: DB_HOST, port: DB_PORT });
  		await query.run(connection);
  		await connection.close();
  	} catch (err) {
  		return 'Fail to update a worklog!';
  	}
  	return 'Update worklog successfully!';
  }
new_contents: // RethinkDB
  import r from 'rethinkdb';
  // Constants
  import { DB_HOST, DB_PORT } from '../../constants/configurations.js';
  import moment from 'moment';
  
  // create a worklog
  export async function createWorkLog(worklog){
  	let connection = null,
  		query = null;
  
  	try {
  		
  		worklog.create_date = moment().utc().format('x');
  		worklog.update_date = worklog.create_date;
  		query = r.db('work_genius').table('worklog').insert(worklog);
  		connection = await r.connect({ host: DB_HOST, port: DB_PORT });
  		let result = await query.run(connection);
  		await connection.close();
  		let id = '';
          if (result && result.generated_keys && result.generated_keys.length > 0){
            id = result.generated_keys[0];
          }
          return id;
  	} catch (err) {
  		return 'Fail to create a worklog!';
  	}
  };
  
  //update a worklog
  export async function updateWorkLog(id, worklog){
  	let connection = null,
  		query = null;
  
  	try {
  		
  		if(worklog.id){
  			delete worklog.id;
  		}
  		worklog.update_date = moment().utc().format('X') * 1000;
  		query = r.db('work_genius').table('worklog').get(id).update(worklog);
  		connection = await r.connect({ host: DB_HOST, port: DB_PORT });
  		await query.run(connection);
  		await connection.close();
  	} catch (err) {
  		return 'Fail to update a worklog!';
  	}
  	return 'Update worklog successfully!';
  }
subject: set the value of update_date when create worklog