Running a Sails App - Installing dependancies

When trying to start a Sails App, it resulted in below few errors

module.js:327

    throw err;

    ^

Error: Cannot find module 'request-promise'

    at Function.Module._resolveFilename (module.js:325:15)

    at Function.Module._load (module.js:276:25)

    at Module.require (module.js:353:17)

    at require (internal/module.js:12:17)

This appeared to be because some of the modules are not installed. This could get resolved by installing packages 

using the commands such as below 

npm install request-promise

references:

http://stackoverflow.com/questions/9023672/nodejs-how-to-resolve-cannot-find-module-error