Exercise (Video): Mongoose ODM Part 1

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Del curso dictado por The Hong Kong University of Science and Technology

Server-side Development with NodeJS, Express and MongoDB

337 calificaciones

The Hong Kong University of Science and Technology

Server-side Development with NodeJS, Express and MongoDB

337 calificaciones

Curso 4 de 4 en SpecializationFull-Stack Web Development with React

This course deals with all things server-side. We base the entire course around the NodeJS platform. We start with a brief overview of the Web protocols: HTTP and HTTPS. We examine NodeJS and NodeJS modules: Express for building web servers. On the database side, we review basic CRUD operations, NoSQL databases, in particular MongoDB and Mongoose for accessing MongoDB from NodeJS. We examine the REST concepts and building a RESTful API. We touch upon authentication and security. Finally we review backend as a service (BaaS) approaches, including mobile BaaS, both open-source and commercial BaaS services. At the end of this course, you will be able to: - Demonstrate an understanding of server-side concepts, CRUD and REST - Build and configure a backend server using NodeJS framework - Build a RESTful API for the front-end to access backend services

De la lección

Data, Data, Where art Thou Data?

This module looks in detail at data storage with MongoDB, the popular NoSQL database. You will learn first about Express generator for scaffolding an Express application. Then you will learn about MongoDB. You will learn how to interact with MongoDB from a Node application. Then you will learn the Mongoose ODM to create schemas and models, and interact with MongoDB server.

Mongoose ODM18:12

Exercise (Video): Mongoose ODM Part 115:37

Exercise (Video): Mongoose ODM Part 213:59

Conoce a los instructores

Jogesh K. Muppala
Associate Professor
Department of Computer Science and Engineering

Now that we have had a quick overview of Mongoose ODM and

how Mongoose brings schemas to structure the documents that we store in our MongoDB,

let's look at how we make use of

the Mongoose node module and then incorporate it into our node application.

Then use Mongoose to communicate with

our MongoDB server and then store and retrieve

documents with structure information in the documents.

To get started on this exercise,

go to a convenient location on your computer.

So, here I am in the Node JS folder where I have been storing

all the examples from this course and then I'm going to

create a new folder named node Mongoose.

This is where we will create the node application using Mongoose next.

In the terminal or the command window,

move to the node Mongoose folder and then initialize a node application there.

So, let me type npm init and then

initialize the node application and then I would name the application

as node-Mongoose and the entry point is index.js git history,

keywords, author and license and we'll say okay.

Once your node package.json file is created,

open the project in the text editor of your choice.

So, here I have my project open in Visual Studio.

Let me go into the package.json file and then add in

the startup script and then we'll

say start node index as usual whenever we start out with a new node application.

Then, going to the terminal or the command window, let's install Mongoose.

So, at the prompt type npm install Mongoose, save.

Which at the moment is Mongoose 5.1.7.

So, these are the versions that I'm going to be using in this course.

Then going to my application in the editor.

Let me create a sub folder in the project called as Models.

So, this is where I'm going to be storing all the models for my application.

In the models folder,

let me create a new file named dishes.js.

So, this is where I'm going to create the schema and the model

for my dishes document that I'm going to store,

the dishes collection which stores the documents for each dishes.

So, right there, let me first import Mongoose.

So, we'll require Mongoose in this file and then say

const schema is Mongoose schema.

Then, we'll create the schema here.

So, we'll say const dishSchema new Schema.

So, this is where I define the schema for my dish.

Inside this schema, let me define the various values.

So, I'll say name,

which is the type String.

So, this is the Schema type and then this I would declare as required.

So, I'll say true.

So, every document will have the name as a required field there and then I

will also declare this as unique meaning that

no two documents should have the same name field in there.

So, that is the first field in my document.

Then, we will also include another field called as, description.

The description is of the type string and required true.

Also, we can have Mongoose automatically insert

timestamps into our model.

So, right there we can just set up the flag time stamps: true.

So, this will automatically add the created at and updated at,

two timestamps into each document that is stored

in our application and it'll automatically update these values.

Whenever we update the document and the created at will be automatically

initialized when the document is first creator of this time.

After this, we will say var Dishes.

So, given the schema,

now we going to construct the model from this schema.

So, we'll say Mongoose model and dish,

and this is going to be using the dish schema that we have just declared earlier.

Then we will export

this model from this file here.

So, we'll say module export dishes.

So, now we have constructed

the Mongoose schema and the corresponding model and the model is now exported from here.

So, this can be imported in our application and used.

So, within our project folder,

let me create a new file named index.js.

In the index.js file,

let me first require Mongoose,

and then after this we can say

const Dishes require models dishes.

Because we have already created the Dishes model in

the models dishes file there and then we are requiring it here.

Now, to establish the connection to the Mongo server,

we'll say const URL mongodb.

Localhost 27017, conFusion.

So, this database is the one that we will connect to from our application and

then after that we can establish the connection by saying const connect Mongoose.

Mongoose supports this connect method,

which takes the URL as the first parameter.

So once we have established this,

then we simply say connect then.

Note that since we are already using promises,

we can just say connect then and then this will take

a function as the parameter

and inside here we can now connect to the database.

So now once this connection is established,

let me do a console log

saying connected correctly to the server,

and here I can create a new Dish by saying var

new Dish and then Dishes and inside here I can specify a document so I'm creating

a new Dish of this kind and then so in here I will

specify the two fields that are required.

So I'll say name,

description and so this is how you would create a new Dish and then once we create

a new Dish from the model we'll simply say new Dish save.

The save method will cause this Dish value to be

saved and then as you expect will return a promise and

then in here we will get the Dish value as call back in there and then,I

can simply log the Dish value here and then after that we'll say

Dishes find and so we'll find

all the Dishes and then say exec.

The exec will ensure that this is

executed and that it will return a promise and so that promise will

be returned so that it can then

chain the method to the remaining ones.

So you see how I am using promises and then I am invoking the previous method so this one

finds all the Dishes within my database,

in the Dishes collection and then makes it available to me.

So when I get the Dishes then I can just console log the Dishes just to see what is

returned and this obviously at this stage should

return this one single Dish that I've inserted into

my Dishes collection and then we will say

return Dishes remove with

an empty JavaScript object which will remove all the Dishes from

the database and return

mongoose connection close which closes the connection to the database.

And catch any error at this point.

So we'll use the catch and then console log.

That's it. So what we are doing here is we're creating the new this Dish and then we are

saving the Dish then we are finding all the Dishes from the collection.

That's it. We are using promises here,

so we have chained all the dens in here. That's it.

Let's save the changes and then see this application executing.

Go into to the terminal,

at the prompt type npm start and you will

see that my node application runs and then it shows,

first, that it has created this particular Dish.

Note in particular, that these two fields,

updated at and created at,

these two timestamps have automatically been added into

the Dish here and so you can see that the created at and

updated at timestamps are exactly the same at the moment and

then the ID is also automatically added in.

In the next step we are printing out all the Dishes that have been retrieved and so you

can see that this one single Dish is in the collection,

Dishes collection, and that is what is printed out on the screen here.

Let's now initialize the Git repository and then let's set up the got gitignore file

so going to the editor then we create the.gitignore file and then add

node modules to the gitignore file and save the changes and

then going back to the prompt let me

type git status and we see that

we have these files that have not been checked in so we'll say

git add and then git

commit the message Mongoose Part One.

With this we complete this exercise.

In this exercise we have seen how easy it is to set up a node application with

mongoose and connect to our MongoDB server and then interact with it.

Now since mongoose builds upon the MongoDB server,

Mongoose can access all the various methods

that are supported by the MongoDB driver also.

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