Defining document instance methods

Documents have their own built-in instance methods such as save and remove. However, we can write our own instance methods as well.

Documents are instances of models. They can be explicitly created:

      const instance = new Model() 

Or they can be the result of a query:

      Model.findOne([conditions]).then((instance) => {}) 

Document instance methods are defined in the schema. All schemas have a method called method which allows you to define custom instance methods.

Getting ready

In this recipe, you will define a schema and custom document instance methods for modifying and reading document properties. First, ensure that you have MongoDB installed and it's running. As an alternative, if you prefer, a MongoDB DBaaS instance in the cloud will also do. Before you start, create a new package.json file with the following code:

{ 
  "dependencies": { 
    "mongoose": "5.0.11" 
  } 
} 

Then, install the dependencies by opening a Terminal and running this code:

npm...