Mongoose Notebook

• Mongoose Notebook
  • About Mongoose
  • Mongoose Schema
  • Models
  • Virtual properties
  • Instance Methods
  • Static Methods
  • Middlewares

About Mongoose

• ODM(Object Data Modeling) lib for MongoDB and Node.js

• manages relationships between data, provides schema validation and it is used to translate between obj in code and the repr of those object in MongoDB

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Mongoose Schema

• document data structure (shape of the document) that is enforced via the app layer

---

Models

• high-order constructors that take schema and create an instance of a document

• wrapper on the Mongoose Schema

• provides an interface to the db for creating, updating etc...

---

Virtual properties

• not persisted to the database

userSchema.virtual('fullname').get(function () {
    return `${this.firstName} ${this.lastName}`;
})

userSchema.virtual('fullname').set(function (name) {
    const str = name.split(' ');
    
    this.firstName = str[0];
    this.lastName = str[1];
})

// Use case
const model = new UserModel();

model.fullname = 'Andrei Gatej';

---

Instance Methods

• helper methods on the schema

• accessed via the model instandce

• will have access tot the model object

userSchema.methods.getInitials = function () {
    return this.firstName[0] + this.lastName[0];
}

// Use case
console.log(model.getInitials())

---

Static Methods

• accessible via the Model Class

userSchema.statics.getUsers = function () {
    return new Promise((resolve, reject) => {
        this.find((err, docs) => {
            if(err) {
                console.error(err)
                return reject(err)
            }

            resolve(docs)
        })
    });
}

// Use case
UserModel.getUsers()
  .then(console.log)
  .catch(console.error)

---

Middlewares

• functions that run at specific stages of a pipeline

• for the following operations: Aggregation, Document, Query, Model

• pre and post take 2 params:

  • the type of the event: init, validate, savec, remove
  • cb tjat os executed wotj this referencing the Model Instance

User Model -> Pre-save Middl ->   save  -> Post save Middl
                |                   |               |
                |                   |               |
        generate pass hash      write to DB     send email when user acc is created