Persisting Data with Vapor 3 and PostgreSQL

A server-side Swift tutorial

Johann Kerr
Jul 31, 2018 · 8 min read

At Flatiron School, our team culture encourages learning new tech and sharing knowledge. We constantly look for new technologies to work on and experiment with. We aren’t currently using any Vapor/Swift internally, but as an iOS & Web developer, Server Side Swift continues to fascinate me, so I wanted to put together a tutorial on how to use PostgreSQL (an open source relational database) and Vapor 3 (a server side Swift framework) to store our data.

If you’re not totally familiar with using SQL, have no fear: Vapor comes with an ORM (Object Relational Mapping Tool) called Fluent that makes working with databases very easy.

Before we dive in, let’s take care of a little housekeeping. Ensure that you have the following:

To check your version of the Vapor Toolbox, open your terminal and type the following:

For this tutorial, we’re going to be building a simple application to keep track of meals you enjoy.

Step 1 — Generate a new Vapor project

Inside of your terminal, enter vapor new foodtracker

Step 2 — Generate an Xcode project file

In terminal, type cd foodtracker && vapor xcode -y .The -y flag tells the vapor xcode generator to automatically open the .xcodeproj file.

Now that we have Xcode open, let’s go ahead and start our server. First, we need to change our scheme from the foodtracker-Package package to Run:

Click on foodtracker-Package

Next, click the run button or hit Cmd + R to start up your server.

Once, it has finished building, navigate to localhost:8080/hello

Now that we have Vapor up and running, let’s add PostgreSQL.

Step 3 — Install PostgreSQL

In terminal, type brew install postgresql.

Note: If you don’t have Homebrew installed yet, you should! Homebrew is a package manager that helps developers install tools to their MacOS devices.

Once postgresql is installed, let’s install This is a small program that makes running PostgreSQL on your machine easy. Once you’ve installed, let’s run it.

Step 4 — Create database for foodtracker

In your terminal, enter psql. This will allow us to type SQL statements into our terminal to manage our database. In our terminal, type CREATE DATABASE foodtracker;.

Once your database has been created you will notice a new database in

Step 5 — Connect Vapor to PostgreSQL

To use PostgreSQL with Vapor, we will be using the FluentPostgreSQL Provider. Firstly, what is a provider?

The Provider protocol make it easy to integrate external services into your application. — Vapor Documentation

To add a provider to your Vapor application, you first need to add the package to Vapor. To do this, we need to replace fluent-sqlite with fluent-postgresql. Add the following line to your Package.swift:

Also replace the target FluentSQLite with FluentPostgreSQL. Your Package.swift should look like this:

To install our new package, return to your terminal and enter vapor xcode -y This will re-fetch the our packages and generate an Xcode project.

Step 6 — Configure Vapor to work with PostgreSQL

First, things first, we need to remove some of the old code that came with our project that is configured to use SQLite.

We need to delete Todo.swift and TodoController.swift. Your folder structure should look like this:

In routes.swift, we also need to remove the reference to TodoController.swift:

Now, we need to configure our application by changing the code in configure.swift.

First, let’s change the import on Line 1 from import FluentSQLite to import FluentPostgreSQL. We also need to register our new provider. In the beginning of the configure method, we need to write the following:

Next, we need to create a PostgreSQLDatabaseConfig and initialize our PostgreSQLDatabase object using our configuration:

let postgres = PostgreSQLDatabase(config: config)

There are a couple of things to note here. The hostname points to our local computer and 5432 is the default port that postgreSQL runs on. The database string here matches the database we just created.

Finally, let’s add our new postgres database to our DatabaseConfig object:

Your code should now look like the following:

Step 7 — Add Vapor model

For this project, we’re going to create a Meal model to track food. Let’s create a Meal.swift file and add it to our models group.

Add the following code to your new file:

final class Meal: PostgreSQLModel {
var id: Int?

If you have any experience with a SQL based database, the id property here should be familiar to you. In SQL databases, new records are identified uniquely using what is known as primary key. Imagine a school registration system where you store information on students. It is conceivable that two students could have the same name, for example “John Smith”. By storing a primary key like id, we can distinguish between one John and the next.

Let’s add a new property to our meal class like description and an initializer. Our class should now look like this:

Finally, let’s import Vapor at the top of this class and adopt a few more protocols to our class:

/// Allows `Todo` to be encoded to and decoded from HTTP messages.
extension Meal: Content { }
/// Allows `Meal` to be used as a dynamic parameter in route definitions.
extension Meal: Parameter { }

Our final class should look like this:

In our database, we must have a table to match the model we just created. To do this we need to create a migration.

Step 8 — Create migration

Creating a migration with Fluent is simple. Navigate to the configure.swift file and after the creation of our MigrationConfig object, add the following line:

Now let’s run our project in Xcode.

In your terminal, we can see that our migrations have run, and our server is running. Now we want to be able to see the new table we have created. One of the easiest ways to do this is to download a PostgreSQL client like Postico. This will allow us to directly connect to our database and use a GUI to interact with our tables.

Once we connect to our database, we should see the tables we created:

If we click into the Meal table, we can see an empty table with the property we created.

Let’s go ahead and add a new record and save it.

Now, that our database and tables are working as expected we can create routes to allow us to interact with them.

Step 9 — Create a Meal Controller

Inside of our controller group, create a new file called MealController.swift.

Let’s add the following code to our controller:

final class MealController {
func index(_ req: Request) throws -> Future<[Meal]> {
return Meal.query(on: req).all()

func create(_ req: Request) throws -> Future<Meal> {
return try req.content.decode(Meal.self).flatMap { meal in
return req)

In the index method, we use one of Fluent’s query methods to return all of the Meal objects stored in our database.

Note that this method returns a Future<[Meal]>. Vapor utilizes the Future type to provide a reference to an object that isn’t available yet.

In the create method, we decode some JSON that is sent in the request to create a Meal object which we then save. Earlier in this tutorial, we adopted the Content protocol which gives us the ability to decode and encode Swift objects to JSON.

At the bottom of our routes method in the routes.swift file, add the following code:

Let’s run our program and test our routes. To test our routes, it’s best to use a REST client like Postman. This will allow us to test GET and POST requests.

First, we’ll try a GET request at http://localhost:8004/meals.

For the POST request, we will send some JSON data in the body of our request.

Note that if we retry our GET request we should now see two meal records.

Voila! We’ve now persisted data to our database and also retrieved that data back from the database. Find the completed project here.

Thanks for reading! Want to work on a mission-driven team that loves ice cream and server-side Swift? We’re hiring!

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Flatiron Labs

We're the technology team at The Flatiron School (a WeWork…

Flatiron Labs

We're the technology team at The Flatiron School (a WeWork company). Together, we're building a global campus for lifelong learners focused on positive impact.

Johann Kerr

Written by

Software Engineer @FlatironSchool, formerly Lead iOS & Web Instructor at //

Flatiron Labs

We're the technology team at The Flatiron School (a WeWork company). Together, we're building a global campus for lifelong learners focused on positive impact.