Building a REST API with NodeJS,Express and DynamoDB
***************** This is a mock blog (real content coming soon…😉) ***************
this simple example builds REST API with following schema database of users
id:String, email: String ,gender:String, Name: String
The dependencies used in this project are as follows:
"dependencies": {
"aws-sdk": "^2.1341.0",
"dotenv": "^16.0.3",
"express": "^4.18.2",
"nodemon": "^2.0.22"
}
We will create a .env file and store all the Credential needed to connect and communicate with the AWS-DynamoDB. it should look as such
AWS_ACCESS_KEY_ID=BHFAWHJBJHVSES
AWS_SECRET_ACCESS_KEY=MNGk9KBjjhkjDGHVbjbhjDFGCFDS
AWS_DEFAULT_REGION=us-west-1We will set up the configuration for DynamoDB in the file DynamoDB.js
Then we will create the CRUD function to create , read, update and delete user info from dynamodb.
Below is the code for dynamodb.js
import AWS from 'aws-sdk';
import dotenv from 'dotenv';
// here we are loading the environment variables from the .env file
dotenv.config();
// here we are destructuring the AWS object to get the config and DynamoDB object
const{config, DynamoDB} = AWS;
// here we are configuring the AWS environment
AWS.config.update({
region: process.env.AWS_DEFAULT_REGION,
accessKeyId: process.env.AWS_ACCESS_KEY_ID,
secretAccessKey: process.env.AWS_SECRET_ACCESS_KEY,
maxRetries:10,
retryDelayOptions: {base: 200}
})
// here we are creating a new instance of the DynamoDB client
export const dynamoClient = new DynamoDB.DocumentClient();
// this is the name of the table we created in DynamoDB
const TABLE_NAME = "users";
// this is the function that will get all the users from the table, it will return a promise
export const getUsers = async ()=>{
const params = {
TableName:TABLE_NAME
};
return await dynamoClient.scan(params).promise();
}
// this is the function that will get a user by id(individual entry), it will return a promise
export const getUserByID = async (id)=>{
const params = {
TableName: TABLE_NAME,
Key:{
id
}
}
return await dynamoClient.get(params).promise();
}
// this is the function that will add or update a user(if the entry already exist with the same id will update), it will return a promise
export const AddorUpdateUser = async (user)=>{
const params ={
TableName: TABLE_NAME,
Item: user
}
return await dynamoClient.put(params).promise();
}
// this is the function that will delete a user by id, it will return a promise
export const deleteUser = async(id)=>{
const params ={
TableName: TABLE_NAME,
Key:{
id
}
}
return await dynamoClient.delete(params).promise();
}All the routing for different operations , getAllUsers, GetUserById, EditUser & Delete User will be setup in a separate file called index.js.
We will setup a initial home route that will display some message when the server is loaded and running.
we will be using. a middleware that will return our entry in json format
we will be creating 5 separate routes to carry out the CRUD functions via REST API
we will tell set a port where our server will run and listen for any user inputs
Below is the full code covering all these concepts , in index.js file
import express from 'express';
import {getUsers, getUserByID,deleteUser, AddorUpdateUser} from './/dynamodb.js';
const app = express();
// here we are telling express to use the json middleware
app.use(express.json());
// this is the route that will be called when we go to the root of the server; a home page-route
app.get('/',(req,res)=>{
res.send('Welcome to Local Server. Get ready to be amazed')
})
// this is the route that will get all the users from the table
// we are using async/await to handle the promises
// we are using try/catch to handle the errors
app.get('/users', async (req,res)=>{
try {
const users = await getUsers();
res.json(users);
} catch (error) {
console.log(error);
res.status(500).json({error:error.message})
}
})
// this is the route that will get a user by id. need to pass the id as a parameter
app.get('/users/:id', async (req,res)=>{
try {
const users = await getUserByID(req.params.id);
res.json(users);
} catch (error) {
console.log(error);
res.status(500).json({error:error.message})
}
})
// this is the route that will add or update a user
app.post('/users', async(req,res)=>{
const user = req.body;
try {
const newUser = await AddorUpdateUser(user);
res.json(newUser)
} catch (error) {
console.log(error);
res.status(500).json({error:error.message})
}
})
// this is the route that will edit an existing user. need to pass the id as a parameter
app.put('/users/:id',async(req,res)=>{
const user = req.body;
const {id} = req.params;
user.id = id;
try {
const newUser = await AddorUpdateUser(user);
res.json(newUser)
} catch (error) {
console.log(error);
res.status(500).json({error:error.message})
}
})
// this is the route that will delete a user
app.delete('/users/:id', async(req,res)=>{
try {
const user = await deleteUser(req.params.id);
res.json(user)
} catch (error) {
console.log(error);
res.status(500).json({error:err})
}
})
// this is the port that the server will listen to
// we are using the environment variable PORT if it is available, if not we are using 8080
const port = process.env.PORT || 8080;
// here we are telling the server to listen to the port
app.listen(port,()=>{
console.log(`Server is running on port ${port}`)
})Below is the snapshot of GetAllUsers returned in our server
{
"Items": [
{
"email": "bellawati@gmail.com",
"id": "2",
"name": "Bella koirala",
"gender": "female"
},
{
"email": "test@email.com",
"id": "1",
"name": "testing tester",
"gender": "male"
}
],
"Count": 2,
"ScannedCount": 2
}Happy Coding !
This post was last updated on: March 23, 2023