Intro to Mongoose Deleting with a Model

Learning objective: By the end of this lesson, students will be able to delete documents from a MongoDB database using deleteOne() and findByIdAndDelete() in Mongoose.

Deleting documents

Delete operations permanently remove a record from a database. Mongoose provides several methods for deleting documents, either individually or in bulk.

Deleting retrieved documents

One approach is to first retrieve the document, and then remove it from the database using the document instance. This can be useful when you need to check the authorship of a resource before performing a delete operation.

The approach involves two steps:

1. Retrieve the document: Use the findById() method to fetch the document you want to delete.
2. Call upon the deleteOne() method: Once the document is retrieved, call upon its deleteOne() method to delete it from the database.

Let’s take a look at an example:

const id = '6573745144784f6dc034e1df';
const todo = await Todo.findById(id);
await todo.deleteOne();

📚 The deleteOne() method is available on a Mongoose document instance (a retrieved document). It removes the document from the database and returns an object with metadata on the status of the operation.

Simultaneous retrieval and delete

A more direct approach to deletion is the findByIdAndDelete(). It allows you to find a document by its _id and delete it with a single operation.

The findByIdAndDelete() method accepts the unique _id of the document as an argument, removes that document from the database, and returns the document that was removed. If the document cannot be found, the operation will return null.

Let’s take a look at an example:

const id = '6573745144784f6dc034e1df';
const removedTodo= await Todo.findByIdAndDelete(id);

Implementing findByIdAndDelete()

Let’s test some of these examples in our queries.js file.

Build the deleteTodo function

First let’s build a function to delete a todo:

// queries.js

const deleteTodo = async () => {
  const id = '6573745144784f6dc034e1df';
  const removedTodo = await Todo.findByIdAndDelete(id);
  console.log('Removed todo:', removedTodo)
}

Next, we’ll call deleteTodo within the runQueries function:

// queries.js

const runQueries = async () => {
  console.log('Queries running.');
  await deleteTodo();
};

If you haven’t done so already, be sure to remove or comment out any previous methods being called

Run the deleteTodo function

To execute the deleteTodo function, run the queries.js file with the following command:

node queries.js

Check your terminal for the following output:

Removed todo: {
  _id: new ObjectId('6573745144784f6dc034e1df'),
  text: 'Learn JS',
  isComplete: true,
  __v: 0
}