Chapter 8. Interacting with Data – Deleting

We have learned about Creating, Reading, and Updating data using Mongoose. Now it is time to look at the final CRUD operation: deleting.

In this chapter we will:

• Learn how to delete multiple documents in one operation

• Learn how to delete a single document

• Put this knowledge into action by adding the functionality to delete a user account

By the end of this chapter, you will be familiar with the different approaches you can take to delete data, and when it is best to use each one. You will also have added the ability to delete users and projects from your MongoosePM application.

Deleting data

By now it will probably come as no surprise that there are a few different methods for deleting data. The methods are:

• remove(): This method deletes one or more documents from the collection

• findOneAndRemove(): This method finds a single document based on a query object and removes it, passing it to the callback function on successful completion

• findByIdAndRemove(): This method is the same as the findOneAndRemove method, except that it finds a document based on a provided document ID

The remove() method can be used in two ways: as a model method, or as an instance method. When using it as a model method, you pass it a query object and it will remove the matching documents. For example:

User.remove({ name : /Simon/ } , function (err){
  if (!err){
    // all users with 'Simon' in their name were deleted
  }
});

To use the remove() method as an instance method you operate it after a find operation once you have results returned. For example:

User.findOne({ email : 'simon@theholmesoffice...

CRUD – deleting user and projects

That's the theory, so let's see it in action and let a user delete their account. To follow the approach we've been taking through this application, we'll have a page displaying a form and a form handler.

The routes in app.js that we'll use for this are:

app.get('/user/delete', user.confirmDelete); // delete current user form
app.post('/user/delete', user.doDelete);     // Delete current user action

The "Are you sure" page

Before a user deletes the account we want to ask them to confirm this, in case they clicked on the link by accident. So we create a new view as views/user-delete-form.jade:

h1= title
p #{name}, are you sure you want to permanently delete your account? The email address on this account is #{email}
form(id="formUserDelete", method="post", action="")
  input(type="hidden", name="_id", id="_id", value="#{_id}")
  input(type="submit", value="Yes, please delete it!")

And create a controller to map it to the route in routes/user.js:

// GET user delete...

Summary

In this chapter, we have learned how to delete database records using Mongoose methods. We then applied this knowledge to our project and added the ability for a user to delete their profile.

This brings us to the end of the data interaction CRUD section, so you should now have a good idea of how to do most things you want to with data in your applications.

Coming up in the next chapter, we're going to look at validation and see how Mongoose can help us maintain data integrity.