w6- advanced mongodb

Question 1

How to have strongly-typed documents?

Answer 1

MongooseJS

Question 2

MongooseJS

Answer 2

strongly-typed schemas, data validation, data pre-processing, and many other features.

Question 3

one-to-one rel approaches?

Answer 3

author_id as property of book.

let Author = {
_id: 1234,
firstName: ‘Tim’,
lastName: ‘John’,
age: 35
};

let book1 = {
_id: 789,
title: ‘FIT2095 Book’,
author_id: 1234,
isbn: 9876
}

Question 4

Mongoose

Answer 4

object data modelling (ODM) library that provides a modelling environment for your collections.

enforces structure as needed while still keeping the flexibility and scalability of MongoDB.

JavaScript framework commonly used in a Node.js application with a MongoDB database

built-in typecasting, validation, query building, business logic hooks and more out of the box.

Question 5

How does Mongoose interact with MongoDB?

Answer 5

It uses the MongoDB driver to interact with MongoDB storage.
.

Question 6

Mongoose SchemaTypes?

Answer 6

currently contains eight SchemaTypes that a property is saved as when it is persisted to MongoDB.

String

Number

Date

Buffer

Boolean

Mixed

ObjectId

Array

Decimal128

Map

Question 7

SchemaTypes handle the definition of?

Answer 7

defaults

validation

getters

setters

field selection defaults for queries

Question 8

Schema?

Answer 8

Each schema maps to a MongoDB collection and defines the shape of the documents within that collection.

Question 9

Field is mandatory?

Answer 9

required:true
make a field required, set the field an object with two properties: the type and required, which needs a boolean value.

Question 10

age: {
type: Number,
validate: {
validator: function (ageValue) {
return ageValue >= 10 && ageValue <= 110;
},
message: ‘Age should be a number between 10 and 110’
}
}

Answer 10

Validator if it is between 10 and 110

Question 11

age: { type: Number, min: 5, max: 20 }

Answer 11

Anbother way to validator Mongoose

Question 12

created: {
type: Date,
default: Date.now
}

Answer 12

field has default date

Question 13

Boook schema referencing author

Answer 13

author: {
type: mongoose.Schema.Types.ObjectId,
ref: ‘Author’
},

Question 14

Mongoose models?

Answer 14

Models are higher-order constructors that take a schema and create an instance of a document equivalent to records in a relational database

A Mongoose model is a wrapper on the Mongoose schema.

Question 15

Difference b/w mongoose schema and mongoose model?

Answer 15

Mongoose schema defines the structure of the document, default values, validators, etc.,

whereas a Mongoose model provides an interface to the database for creating, querying, updating, deleting records, etc.

Question 16

module.exports = mongoose.model(‘Author’, authorSchema);

Answer 16

to export a model, we need to invoke the model constructor and pass it a string represents the name of the collection and a reference to the schema.

author collection

Question 17

let url=’mongodb://localhost:27017/libDB’;

Answer 17

Mongoose URL string which has syntax: mongodb://ServerAddress: Port//DbName

Question 18

format

Answer 18

adding new book
saving book

Question 19

Note: the creating and saving of book1 and book2 have been implemented inside the callback of author1.save function. Why?? N

Answer 19

Node.js is asynchronous and both book1 and book2 require the author’s ID (lines 31 and 43). Therefore, we have to create them after the save operation of the author is done.

Question 20

.insertMany() function

Answer 20

This function takes as input an array of documents (objects) and inserts them if they are valid.

Question 21

Mongoose models have several static functions that can be used for CRUD operations?

Answer 21

Model.deleteMany()

Model.deleteOne()

Model.find()

Model.findById()

Model.findByIdAndDelete()

Model.findByIdAndRemove()

Model.findByIdAndUpdate()

Model.findOne()

Model.findOneAndDelete()

Model.findOneAndRemove()

Model.findOneAndUpdate()

Model.replaceOne()

Model.updateMany()

Model.updateOne()

Question 22

Using ‘where’, we can create complex expressions. Example: Find all documents with firstName starting with the letter ‘T’ and the age >= 25.

Answer 22

Author.where({ ‘name.firstName’: /^T/ }).where(‘age’).gte(25).exec(function (err, docs) {
console.log(docs);

});

Question 23

What does exec mean?

Answer 23

Note exec indicates the end of the chain and invokes the callback function.

Question 24

and sort the results in ascending order by the age

Answer 24

Author.where({ ‘name.firstName’: /^T/ }).where(‘age’).gte(25).lte(35).limit(10).sort(‘age’).exec(function (err, docs) {
console.log(docs);

});

Question 25

Author.find({ ‘name.firstName’: ‘Tim’ }, ‘age’, function (err, docs) {
//docs is an array
console.log(docs);

});

Answer 25

Retrieving only certain fields Example: get the age of all documents with first name = ‘Tim’

Question 26

Populate?

Answer 26

Mongoose has a powerful aggregation operator called populate(), which allows you reference documents in other collections.

Question 27

Book.find({}).populate(‘author’).exec(function (err, data) {
console.log(data);
});

Answer 27

For exmaple, to get the books and their authors’ details:

Question 28

Author.updateOne({ ‘name.firstName’: ‘Alex’ }, { $set: { ‘name.firstName’: ‘John’ } }, function (err, doc) {
console.log(doc);
});

Answer 28

This document updates only the first document that matches the criteria.

Question 29

Author.deleteOne({ ‘name.firstName’: ‘Tim’ }, function (err, doc) {
console.log(doc);

});

Author.deleteMany({ ‘name.firstName’: ‘Tim’ }, function (err, doc) {
console.log(doc);

});

Answer 29

deleteOne() function deletes a document based on condition (criteria).

This function deletes all the documents that match the criteria.

Question 30

Deployment workflow this unit- 3 stages

Answer 30

1.testing functionality in local machine
2.pushed to a VCS repository i.e Github - intermediary between IDE and GCP VM instances i.e production

clon source code to VM instane- fetch dependencies- build and execute app

IDE ->push->Github->clone-> GCP VM-> production!

Question 31

Cloud computing models!

Answer 31

3 cloud computing models- IaaS
PaaS
SaaS

Question 32

IaaS

Answer 32

Infrastructure as a Service- IaaS is a form of cloud computing that offers virtualized resources over the internet. In this form, you can create your network of resources: Virtual Machines (VMs), firewalls, and load balancers

Question 33

PaaS

Answer 33

Platform as a Service-PaaS is a form of cloud computing where the infrastructure will be created and managed by the cloud vendor, and your responsibility as a developer is to provide the application’s source code.

Question 34

SaaS

Answer 34

Software as a Service- The cloud vendor will manage the infrastructure and application source code in this form.

Question 35

Bootstrap

Answer 35

Bootstrap is the most popular CSS Framework for developing responsive and mobile-first websites.

Question 36

Is integer?

Answer 36

var itemSchema = mongoose.Schema({
_id: mongoose.Schema.Types.ObjectId,
itemName: String,
quantity: {
type: Number,
validate: {
validator: Number.isInteger,
message: ‘The quantity is not an integer value’
}
}
});

Question 37

Retrieve the first 50 documents with quantity between 100 and 150 inclusive.

Answer 37

Items.where(‘quantity’).gte(100).lte(150).limit(50).exec(function (err, docs) {
// Do something with Docs
});

Question 38

const mongoose = require(“mongoose”);
let doctorSchema = mongoose.Schema({
_id: {
type: mongoose.Schema.Types.ObjectId,
auto: true
},
name: {
firstName: {
type: String,
required: true,
},
lastName: String,
}
});

Add a validator to the schema, so it only accepts documents with at least 5 characters in firstName. The message for invalid data is ‘firstName length cannot be less than 5’.

Answer 38

const mongoose = require(“mongoose”);
let doctorSchema = mongoose.Schema({
_id: {
type: mongoose.Schema.Types.ObjectId,
auto: true
},
name: {
firstName: {
type: String,
required: true,
validate:{
validator: function (firstNameValue){
return firstName.length >= 5;
},
message = ‘‘firstName length cannot be less than 5’.
}
},
lastName: String,
}
});

Question 39

What are the roles on param in the following statement:
module.exports = mongoose.model(param, mySchema);

Answer 39

param - unique name i.e String to reference collection , collection name in database.

Question 40

How does populate work in mongoose? Support with example

Answer 40

Mongoose has a powerful aggregation operator called populate(), which allows you reference documents in other collections.

For exmaple, to get the books and their authors’ details:

Book.find({}).populate(‘author’).exec(function (err, data) {
console.log(data);
});