Build a REST API with Express and Sequelize

In this tutorial all steps for building a REST API with Express and Sequelize.

When I started learning Node I made the same mistake as most bootcamp graduates these days. I went straight for NoSQL databases without even considering SQL as an option and I had no idea what I had missed out on until when I was recently exposed to Ruby on Rails and SQL. I learned the difference between the two type of databases and managed to love both of them, equally. Because of my newly found knowledge I decided to write a walkthrough on how to build a REST API using Express and Sequelize.

Let’s start by installing the npm packages that we will use:

npm init
npm install express sequelize sqlite3 body-parser --save
npm install sequelize-cli -g

sequelize init

The command “sequelize init” will create the backbone of our database architecture and will allow us to easily connect to our database to insert/retrieve/delete records. Once that command is completed you will see a couple of extra folders and files in your app and your folder structure should look something like this:

|- express-sequelize
|-- config
|--- config.json
|-- migrations
|-- models
|--- index.js
|-- node_modules
|-- seeders
|-- package.json
|-- package-lock.json

The planned database models and the relationships between them will look something like this:

For this tutorial I will use SQLite3 for the sake of simplicity; in order to use that with Sequelize we have to go into our config/config.json and replace the content of the file with the following:

{
    "development": {
    "dialect": "sqlite",
    "storage": "./database.sqlite3"
  },
    "test": {
    "dialect": "sqlite",
    "storage": ":memory"
  },
    "production": {
    "dialect": "sqlite",
    "storage": "./database.sqlite3"
  }
}

Now that our environment is all set up, it’s time to create the models for our database. Sequelize-CLI allows us to create models on the fly with no effort; we simply have to write the name of the model and the name of the columns in the database that will belong to the current model and the type of data that we will store. Just like this:

sequelize model:create --name Physician --attributes name:string
sequelize model:create --name Patient --attributes name:string
sequelize model:create --name Appointment --attributes physicianId:integer,patientId:integer

After we’re done with this, you’ll see that we have 3 new files inside our *models *folder. All we have to do now is to commit these changes to the database by migrating the changes with the following command:

sequelize db:migrate

This means that our models are created in the database (but, we still have to create the associations between them). We’ll have 2 main models: Physician and Patient. They will be connected by a join table: Appointment. A Physician can have many Patients and vice versa through an Appointment. Let’s start with the Physician. All we have to do is define the association inside the “associate’’ function. The way we do this is on line 11. We select the current model and use the belongsToMany() function that will receive the model we want to connect it to and the optional arguments. In this case we have to include our join table Appointment.

"use strict";
module.exports = (sequelize, DataTypes) => {
  const Physician = sequelize.define(
    "Physician",
    {
      name: DataTypes.STRING
    },
    {}
  );
  Physician.associate = function(models) {
    Physician.belongsToMany(models.Patient, { through: "Appointment", foreignKey: "physicianId" });
  };
  return Physician;
};

We have to do the same with our Patient model:

"use strict";
module.exports = (sequelize, DataTypes) => {
  const Patient = sequelize.define(
    "Patient",
    {
      name: DataTypes.STRING
    },
    {}
  );
  Patient.associate = function(models) {
    Patient.belongsToMany(models.Physician, { through: "Appointment", foreignKey: "patientId" });
  };
  return Patient;
};

And now it’s time to connect these two models with our join model by defining a relationship where Appointment belongs to a Patient and a Physician.

"use strict";
module.exports = (sequelize, DataTypes) => {
  const Appointment = sequelize.define(
    "Appointment",
    {
      physicianId: DataTypes.INTEGER,
      patientId: DataTypes.INTEGER
    },
    {}
  );
  Appointment.associate = function(models) {
    Appointment.belongsTo(models.Physician);
    Appointment.belongsTo(models.Patient);
  };
  return Appointment;
};

This means that our database is ready. It’s time to get started with the Node server. Nothing complicated, just a simple Express server. First of all let’s create a file called server.js and let’s paste this code inside.

const express = require("express");
const bodyparser = require("body-parser");
const port = process.env.PORT || 5000;

const app = express();

app.use(bodyparser.urlencoded({ extended: true }));
app.use(bodyparser.json());

require("./routes/appointmentRoutes")(app);
require("./routes/physicianRoutes")(app);
require("./routes/patientRoutes")(app);

app.listen(port, () => console.log(`Server started on ${port}`));

All that is left is to define the routes where our server will receive requests. For this I will create 3 files inside a folder named “routes”, one file for each model. Each file will have the following routes included:

'GET'    /name
'GET'    /name/:id
'POST'   /name
'PUT'    /name/:id
'DELETE' /name/:id 

In these files we’ll import our models from the database that we’ll use and Sequelize will allow us to call methods on these models that execute specific queries in the database. The content of your files will be almost identical, but with different model names.

This is what “physicianRoutes.js” will look like:

const Physician = require("../models").Physician;
const Patient = require("../models").Patient;

module.exports = function(router) {
  router.get("/physicians", (req, res) => {
    Physician.findAll({
      include: [Patient]
    })
      .then(physicians => {
        res.json(physicians);
      })
      .catch(err => res.json(err));
  });

  router.get("/physicians/:id", (req, res) => {
    Physician.findAll({
      where: { id: req.params.id }
    })
      .then(physician => {
        res.json(physician[0]);
      })
      .catch(err => res.json(err));
  });

  router.post("/physicians", (req, res) => {
    Physician.create({
      name: req.body.name
    })
      .then(res => {
        res.json(res);
      })
      .catch(err => res.json(err));
  });

  router.put("/physicians/:id", (req, res) => {
    Physician.update({ name: req.body.name }, { where: { id: req.params.id } })
      .then(updatedPhysician => {
        res.json(updatedPhysician);
      })
      .catch(err => res.json(err));
  });

  router.delete("/physicians/:id", (req, res) => {
    Physician.destroy({
      where: { id: req.params.id }
    })
      .then(physician => {
        res.json(physician);
      })
      .catch(err => res.json(err));
  });
};

If you compare it to “patientRoutes.js”, the only main difference you will see is the model names.

const Physician = require("../models").Physician;
const Patient = require("../models").Patient;

module.exports = function(router) {
  router.get("/patients", (req, res) => {
    Patient.findAll({
      include: [Physician]
    })
      .then(patients => {
        res.json(patients);
      })
      .catch(err => res.json(err));
  });

  router.get("/patients/:id", (req, res) => {
    Patient.findAll({
      where: { id: req.params.id }
    })
      .then(patient => {
        res.json(patient[0]);
      })
      .catch(err => res.json(err));
  });

  router.post("/patients", (req, res) => {
    Patient.create({
      name: req.body.name
    })
      .then(res => {
        res.json(res);
      })
      .catch(err => res.json(err));
  });

  router.put("/patients/:id", (req, res) => {
    Patient.update({ name: req.body.name }, { where: { id: req.params.id } })
      .then(updatedPatient => {
        res.json(updatedPatient);
      })
      .catch(err => res.json(err));
  });

  router.delete("/patients/:id", (req, res) => {
    Patient.destroy({
      where: { id: req.params.id }
    })
      .then(patient => {
        res.json(patient);
      })
      .catch(err => res.json(err));
  });
};

And “appointmentRoutes.js”:

const Appointment = require("../models").Appointment;
const Physician = require("../models").Physician;
const Patient = require("../models").Patient;

module.exports = function(router) {
  router.get("/appointments", (req, res) => {
    Appointment.findAll({
      include: [Physician, Patient]
    }).then(appointments => {
      res.json(appointments);
    });
  });

  router.get("/appointments/:id", (req, res) => {
    Appointment.findAll({
      where: { id: req.params.id },
      include: [Physician, Patient]
    }).then(appointment => {
      res.json(appointment[0]);
    });
  });

  router.post("/appointments", (req, res) => {
    Appointment.create({
      physicianId: req.body.physicianId,
      patientId: req.body.patientId
    })
      .then(appointments => {
        res.json(appointments);
      })
      .catch(err => res.json(err));
  });

  router.put("/appointments/:id", (req, res) => {
    Appointment.update(
      { physicianId: req.body.physicianId, patientId: req.body.patientId },
      { where: { id: req.params.id } }
    )
      .then(updatedAppointment => {
        res.json(updatedAppointment);
      })
      .catch(err => console.log(err));
  });

  router.delete("/appointments/:id", (req, res) => {
    Appointment.destroy({
      where: { id: req.params.id }
    }).then(appointment => {
      res.json(appointment);
    });
  });
};

These three files will help us to carry out the basic CRUD functionality in our app. Of course we can create more endpoints where we can describe what to do in specific cases or what to return.

This is all for now, if you start up your server and populate your database you can Create, Read, Update and Delete your records.

#node-js #express #rest #api #sql

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What is REST API? An Overview | Liquid Web

What is REST?

The REST acronym is defined as a “REpresentational State Transfer” and is designed to take advantage of existing HTTP protocols when used for Web APIs. It is very flexible in that it is not tied to resources or methods and has the ability to handle different calls and data formats. Because REST API is not constrained to an XML format like SOAP, it can return multiple other formats depending on what is needed. If a service adheres to this style, it is considered a “RESTful” application. REST allows components to access and manage functions within another application.

REST was initially defined in a dissertation by Roy Fielding’s twenty years ago. He proposed these standards as an alternative to SOAP (The Simple Object Access Protocol is a simple standard for accessing objects and exchanging structured messages within a distributed computing environment). REST (or RESTful) defines the general rules used to regulate the interactions between web apps utilizing the HTTP protocol for CRUD (create, retrieve, update, delete) operations.

What is an API?

An API (or Application Programming Interface) provides a method of interaction between two systems.

What is a RESTful API?

A RESTful API (or application program interface) uses HTTP requests to GET, PUT, POST, and DELETE data following the REST standards. This allows two pieces of software to communicate with each other. In essence, REST API is a set of remote calls using standard methods to return data in a specific format.

The systems that interact in this manner can be very different. Each app may use a unique programming language, operating system, database, etc. So, how do we create a system that can easily communicate and understand other apps?? This is where the Rest API is used as an interaction system.

When using a RESTful API, we should determine in advance what resources we want to expose to the outside world. Typically, the RESTful API service is implemented, keeping the following ideas in mind:

• Format: There should be no restrictions on the data exchange format
• Implementation: REST is based entirely on HTTP
• Service Definition: Because REST is very flexible, API can be modified to ensure the application understands the request/response format.
• The RESTful API focuses on resources and how efficiently you perform operations with it using HTTP.

The features of the REST API design style state:

• Each entity must have a unique identifier.
• Standard methods should be used to read and modify data.
• It should provide support for different types of resources.
• The interactions should be stateless.

For REST to fit this model, we must adhere to the following rules:

• Client-Server Architecture: The interface is separate from the server-side data repository. This affords flexibility and the development of components independently of each other.
• Detachment: The client connections are not stored on the server between requests.
• Cacheability: It must be explicitly stated whether the client can store responses.
• Multi-level: The API should work whether it interacts directly with a server or through an additional layer, like a load balancer.

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An API-First Approach For Designing Restful APIs | Hacker Noon

I’ve been working with Restful APIs for some time now and one thing that I love to do is to talk about APIs.

So, today I will show you how to build an API using the API-First approach and Design First with OpenAPI Specification.

First thing first, if you don’t know what’s an API-First approach means, it would be nice you stop reading this and check the blog post that I wrote to the Farfetchs blog where I explain everything that you need to know to start an API using API-First.

Preparing the ground

Before you get your hands dirty, let’s prepare the ground and understand the use case that will be developed.

Tools

If you desire to reproduce the examples that will be shown here, you will need some of those items below.

• NodeJS
• OpenAPI Specification
• Text Editor (I’ll use VSCode)
• Command Line

Use Case

To keep easy to understand, let’s use the Todo List App, it is a very common concept beyond the software development community.

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Opencart REST API extensions - V3.x | Rest API Integration, Affiliate

Opencart REST API extensions - V3.x | Rest API Integration : OpenCart APIs is fully integrated with the OpenCart REST API. This is interact with your OpenCart site by sending and receiving data as JSON (JavaScript Object Notation) objects. Using the OpenCart REST API you can register the customers and purchasing the products and it provides data access to the content of OpenCart users like which is publicly accessible via the REST API. This APIs also provide the E-commerce Mobile Apps.

Opencart REST API 
OCRESTAPI Module allows the customer purchasing product from the website it just like E-commerce APIs its also available mobile version APIs.

Opencart Rest APIs List 
Customer Registration GET APIs.
Customer Registration POST APIs.
Customer Login GET APIs.
Customer Login POST APIs.
Checkout Confirm GET APIs.
Checkout Confirm POST APIs.

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Get Bank Details Rest API
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Get Genealogy JSON Rest API
Get Total Earning Rest API
Get Current Balance Rest API
Get Payout Details Rest API
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Withdrawal Request Rest API
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Why You Should Consider Low-Code Approach to Building a REST API

APIs have been around for decades – they allow different systems to talk to each other in a seamless, fast fashion – yet it’s been during the past decade that this technology has become a significant force.

So then why all the interest in APIs? We all know the usual stories – Uber, Airbnb, Apple Pay… the list goes on, and the reasons are plentiful. Today the question is, how? Perhaps you are looking to differentiate your business or want a first-mover advantage.  How can you execute quickly and at low cost/risk to try new market offerings?

An API provides several benefits to an organisation, but without a dedicated team of trained developers, it might seem like an implausible option. Developers are expensive, and it can take months to develop an API from the ground up. If you don’t fancy outsourcing or have the capability in house to build internal APIs, a low-code platform might just be the answer.

Before You Begin: Plan long-term, start small.

For a small one-page application, this might only be a day or two of talking with stakeholders and designing business logic. The purpose of this first step is to ensure that the API will cover all use cases and provides stakeholders with what they need. Refactoring an entire coding design due to missing business logic is not only frustrating for the development team but adds high cost and time to the API project.

During the planning and design stage, remember that running an API requires more infrastructure than just resources to execute endpoint logic. You need a database to store the data, an email system to send messages, storage for files, and security to handle authorisation and authentication. These services can be farmed out to cloud providers to expedite the API build process (e.g. AWS provides all these infrastructure components, but Microsoft Azure is an optional cloud provider with SendGrid as the email application.)

**Planning considerations: **An API “speaks” in JSON or XML, so the output provided to client applications should be decided. Should you choose to later create endpoints for public developer consumption, you could offer both for ease-of-use and fostering more adoption. Ensuring the API follows OpenAPI standards will encourage more adoption and attract more developers.

#api #rest-api #api-development #restful-api #low-code-platform #low-code #build-a-rest-api #low-code-approach