Welcome to Build and Deploy a REST API with Deno!

How to Install Deno Locally and in Docker Containers

Introduction

Deno vs Node: A Deno Fresh Start to JavaScript Runtimes

How to Use the Deno REPL Command Line Interface

Executing TypeScript Files With Deno With the Config File

Deno vs Golang's Standard Library

How to Start a Deno Server and Set Permissions

How to Build a Token Authentication Server With Deno

Getting Started with Deno

Using Databases with Deno

How to Use PostgreSQL in Docker with Deno

How to Integrate MySQL or MariaDB With Deno

How to Add SQLite to Deno with deno-sqlite

Connect to a database

What is Database Migration? The Strategy to Migrate Data

How to Add Nessie to Deno to Migrate Databases

How to Create a New Database Migration With Deno Nessie

Edit a Deno Nessie Database Migration to Catch Errors

How to Run and Roll Back a Database Migration With Deno Nessie

How to Create a Database Seed File With Deno Nessie

How to Import JSON Data and Seed a Database With Deno Nessie

Database migrations

REST API Introduction

Best Practices for a REST API: Endpoints and Database Schema

How to Prepare Deno to Build a REST API

How to Build REST API Endpoints in Deno

Integrate a PostgreSQL Database With Nessie Into a Deno API

Building a MySQL or PostgreSQL Database Pool in Deno

Migrating Data to PostgreSQL and Modeling Data in Deno

Build API Calls That Generate SQL Queries in Deno

Create a Database Controller in Deno

How to Authenticate and Authorize REST API Requests in Deno

Create New Tables and Models With Deno Database Migration

Add List, Create, Read, Update, and Delete Requests in Deno

How to Build Many-to-Many Namespace Connections in Deno

API Afterthoughts

REST API

Deployment Introduction

How to Create a Docker Image to Containerize an Application

How to Create Continuous Integration Files for GitHub and GitLab

How to Deploy a Deno API Server With the Digital Ocean API

How to Deploy a Deno Docker Image to Digital Ocean

Deploy with Docker

Deployment

deno

In this course, we will learn how to work with [Deno](https://deno.land) to create a REST API using TypeScript with the web framework [Oak](https://github.com/oakserver/oak) and the migration tool [Nessie](https://github.com/halvardssm/deno-nessie). 
Deno is a JavaScript runtime created by [Ryan Dahl](https://tinyclouds.org), the same creator for Node, as an attempt to simplify the JavaScript landscape by strictly following the WebAPI specs. 
If you are interested in learning more about the motivation behind Deno, you can watch this video where Ryan Dahl explains "[10 Things I Regret About Node.js](https://www.youtube.com/watch?v=M3BM9TB-8yA)"

We will explore how to create an application using the powers of TypeScript, and learn how to traverse the Deno ecosystem which is much like the native web ecosystem. 
There are 5 modules that will take you from installing Deno and running your first lines of code, to working with web frameworks and databases, and in the end, deploying your application to a web server using a deployment pipeline.

Throughout this course, you will experience all the different aspects of Deno which you will need to create your own application in the future. 
And from this course, you will get a good feeling for if Deno is ready to be your next default for new projects.

In this course, we will learn how to create and deploy a REST API with Deno from scratch.

Build and deploy a REST API with Deno

Integrating databases into your application

Importance of database migrations in production applications

Deploying Deno applications to production using CICD

In the previous steps, we created a basic Duck model and connected the database
pool to our application. In this step, we will be adding the queries to our

 class which allows us to use Deno to communicate with the database, and
insert and fetch data.

, in
short DAO, is widely used to separate application logic from the database logic.
As with everything else, this is a design decision for our application, and we
will be using it to separate the router/controller from the database logic. If
you really wanted to, you could write everything in one file, but that wouldn't
be very nice to work with as the file would quickly become quite big and
convoluted. But remember, it always depends on your application, so in some
cases it might be better, cleaner, or more efficient to have everything in one
file. In short, it depends!

To create a Duck, we first need to add a way of inserting data into the
database.

import { AppRouterContext } from "../../main.ts";

  static async create(
    ctx: AppRouterContext,
    data: Partial<Duck>,
  ): Promise<Duck> {
    const id = await this.getUniqueId(ctx);

    const client = await ctx.app.state.pool.connect();

    const result = await client.queryObject(
      `INSERT INTO ${this.TABLE_NAME} (${this.COL_ID}, ${this.COL_USERNAME}, ${this.COL_PASSWORD}) VALUES ($1, $2, $3) RETURNING *`,
      id,
      data.username,
      data.password,
    );

    await client.release();

    return result.rows[0] as Duck;
  }

In the code snippet above, we are using something called a prepared statement
for our database insert. If you are not familiar with the concept, it simply
protects the database against SQL injections as you can't simply pass in the
username 

 or something similar. You may wonder, "but we are
using string templates, isn't this the same thing??". Well no, we are using
internal constants in the code above to fill in the table name and columns,
which is not the same as enabling user input directly into the statement.

We start the method by getting an available client from the 

 by using the
global state. When you access 

, it is simply a clone of the state,
while 

 is the actual state where you can access the 

When retrieving a new client from the pool, we also need to release it once we
are done, or at some point there may no longer be any available connections.

Lastly, if you look at the last part of the insert statement, we are returning
the new row. This means we get an output which we can cast to the type 

---
title: Duck DAO
description: Creating the methods to access the database using our model
---

## Duck DAO (Data Access Object)

In the previous steps, we created a basic Duck model and connected the database
pool to our application. In this step, we will be adding the queries to our
`Duck` class which allows us to use Deno to communicate with the database, and
insert and fetch data.

A [Data Access Object](https://en.wikipedia.org/wiki/Data_access_object), in
short DAO, is widely used to separate application logic from the database logic.
As with everything else, this is a design decision for our application, and we
will be using it to separate the router/controller from the database logic. If
you really wanted to, you could write everything in one file, but that wouldn't
be very nice to work with as the file would quickly become quite big and
convoluted. But remember, it always depends on your application, so in some
cases it might be better, cleaner, or more efficient to have everything in one
file. In short, it depends!

### Create Duck

To create a Duck, we first need to add a way of inserting data into the
database.

Add the `AppRouterContext` import from our `main.ts` file like so:

```typescript { actualFilename=../../code/module_4.3.3/src/duck/model.ts endLine=1 startLine=1 statedFilename=src/duck/model.ts url=https&#x3A;//gitlab.com/fullstackio/books/build-and-deploy-a-rest-api-with-deno/module_04/lesson_03.03/.../code/module_4.3.3/src/duck/model.ts }
import { AppRouterContext } from "../../main.ts";
```

And add the following method to the `DuckModel` (and ignore that `getUniqueId`
does not exist for now):

```typescript { actualFilename=../../code/module_4.3.3/src/duck/model.ts endLine=34 startLine=16 statedFilename=src/duck/model.ts url=https&#x3A;//gitlab.com/fullstackio/books/build-and-deploy-a-rest-api-with-deno/module_04/lesson_03.03/.../code/module_4.3.3/src/duck/model.ts#L16 }
  static async create(
    ctx: AppRouterContext,
    data: Partial<Duck>,
  ): Promise<Duck> {
    const id = await this.getUniqueId(ctx);

    const client = await ctx.app.state.pool.connect();

    const result = await client.queryObject(
      `INSERT INTO ${this.TABLE_NAME} (${this.COL_ID}, ${this.COL_USERNAME}, ${this.COL_PASSWORD}) VALUES ($1, $2, $3) RETURNING *`,
      id,
      data.username,
      data.password,
    );

    await client.release();

    return result.rows[0] as Duck;
  }
```

In the code snippet above, we are using something called a prepared statement
for our database insert. If you are not familiar with the concept, it simply
protects the database against SQL injections as you can't simply pass in the
username `;drop database ...;` or something similar. You may wonder, "but we are
using string templates, isn't this the same thing??". Well no, we are using
internal constants in the code above to fill in the table name and columns,
which is not the same as enabling user input directly into the statement.

We start the method by getting an available client from the `pool` by using the
global state. When you access `ctx.state`, it is simply a clone of the state,
while `ctx.app.state` is the actual state where you can access the `pool`.

When retrieving a new client from the pool, we also need to release it once we
are done, or at some point there may no longer be any available connections.

Creating the methods to access the database using our model

Learn

The newline Guide to Building Your First GraphQL Server with Node and TypeScript

Teach

Amelia Wattenberger

Author of Fullstack D3

Community

Build and deploy a REST API with Deno

Module 1: Introduction

Introduction:

Start Here

Introduction:

Welcome to Build and Deploy a REST API with Deno!

Lesson:

How to Install Deno Locally and in Docker Containers

Module 2: Getting Started with Deno

Introduction:

Deno vs Node: A Deno Fresh Start to JavaScript Runtimes

Lesson 1:

How to Use the Deno REPL Command Line Interface

Lesson 2:

Executing TypeScript Files With Deno With the Config File

Lesson 3:

Deno vs Golang's Standard Library

Lesson 4:

How to Start a Deno Server and Set Permissions

Lesson 5:

How to Build a Token Authentication Server With Deno

Module 3: Connect to a database

Introduction:

Using Databases with Deno

Lesson 1:

How to Use PostgreSQL in Docker with Deno

Lesson 2:

How to Integrate MySQL or MariaDB With Deno

Lesson 3:

How to Add SQLite to Deno with deno-sqlite

Module 4: Database migrations

Introduction:

What is Database Migration? The Strategy to Migrate Data

Lesson 1:

How to Add Nessie to Deno to Migrate Databases

Lesson 2:

How to Create a New Database Migration With Deno Nessie

Lesson 3:

Edit a Deno Nessie Database Migration to Catch Errors

Lesson 4:

How to Run and Roll Back a Database Migration With Deno Nessie

Lesson 5:

How to Create a Database Seed File With Deno Nessie

Lesson 6:

How to Import JSON Data and Seed a Database With Deno Nessie

Module 5: REST API

Introduction:

REST API Introduction

Lesson 1:

Best Practices for a REST API: Endpoints and Database Schema

Lesson 2:

How to Prepare Deno to Build a REST API

Lesson 3:

How to Build REST API Endpoints in Deno

Lesson 4:

Integrate a PostgreSQL Database With Nessie Into a Deno API

Lesson 5:

Building a MySQL or PostgreSQL Database Pool in Deno

Lesson 6:

Migrating Data to PostgreSQL and Modeling Data in Deno

Lesson 7:

Build API Calls That Generate SQL Queries in Deno

Lesson 8:

Create a Database Controller in Deno

Lesson 9:

How to Authenticate and Authorize REST API Requests in Deno

Lesson 10:

Create New Tables and Models With Deno Database Migration

Lesson 11:

Add List, Create, Read, Update, and Delete Requests in Deno

Lesson 12:

How to Build Many-to-Many Namespace Connections in Deno

Lesson 1:

API Afterthoughts