Book Image

Mongoose for Application Development

By : Simon Holmes
Book Image

Mongoose for Application Development

By: Simon Holmes

Overview of this book

Mongoose is all about putting the data model where it should be: in your application. You can control everything from within your application in JavaScript, eliminating the need to work with the database or a separate management system. Mongoose for Application Development is a practical, hands-on guide that takes you from installing the technology stack through the steps of developing a web application. It covers the key features of Mongoose and how to use them to rapidly develop a Node.js and MongoDB application. This book introduces the full technology stack of Node.js, MongoDB, Express, and Mongoose. It will take you through the process of building an application on this stack with a focus on how Mongoose makes the process quicker and easier. You will see how Mongoose removes a layer of complexity when dealing with MongoDB whilst giving you more control over your data from your application. You will learn how to define schemas and models for your data in JavaScript. Using these schemas and models, you will learn how to build the cornerstone of any web application that will include CRUD operations (creating, reading, updating, and deleting data). If you want to learn how to build applications quickly and efficiently using Node.js, then Mongoose and this book are ideal for you. Using practical examples throughout, Mongoose for Application Development not only teaches you about the concepts of Mongoose, but walks through how to use them to build a real-life application.
Table of Contents (18 chapters)
Mongoose for Application Development
Credits
About the Author
About the Reviewers
www.PacktPub.com
Preface
Index

Understanding validation errors


When we have been creating, editing, and saving data in our project, we have been using a callback function containing two parameters: an error object and the returned data object. So far we have generally been ignoring the error object and just been saving the data, for example:

user.save(function (err, user) {
  if(err){
    console.log(err)
  } else { ...

It is in the err object that we receive the Mongoose validation errors. The error object will contain a top-level message and name, and a collection of specific errors. Each of these errors give an individual message, name, path, and type object. A typical validation failure looks like the following when sent to the console:

{ message: 'Validation failed',
  name: 'ValidationError',
  errors: 
   { email: 
      { message: 'Validator "required" failed for path email',
        name: 'ValidatorError',
        path: 'email',
        type: 'required' },
     name: 
      { message: 'Validator "required" failed...