go_movies_api_rest

Build, manage & deploy a RESTful JSON API (a movies web application)in GO.

Database Setup and Configuration

You'll need to install PostgreSQL.

brew install postgresql@15  # mac

sudo apt install postgresql # ubuntu

psql --version

Connecting to the PostgreSQL Interactive Terminal

sudo -u postgres psql

# now the prompt should become like: postgres=#

Check out the current user

SELECT current_user;

-- you can also use meta command to check the users:
\du
-- the following lists all the databases
\l
-- list the tables
\dt

Create the project databae & connect to it.

CREATE DATABASE moviesdb;

\c moviesdb -- connect to the database created
/*
Now the prompt should look like: moviesdb=#
*/

CREATE ROLE moviesdb_user WITH LOGIN PASSWORD 'Ch@ng3M3!';

/*
citext extension adds a case-insensitive character string to PostgreSQL.
We'll use this to store user email adresses.
*/
CREATE EXTENSION IF NOT EXISTS citext;

exit

Connect as the new user

psql --host=localhost --dbname=moviesdb --username=moviesdb_user
# You'll be prompted to enter the password for the user.

-- Now you should be connected to the `moviesdb` & the prompt looks like: moviesdb=>
SELECT current_user;

exit

Connecting to PostgreSQL from Go

We'll be needing a database driver to act as the middleman between Go and the database itself. We'll be using the pq package.

go get github.com/lib/pq@v1

We also want to decouple the connection string, aka DSN, from our Go code. So, in our go application we'll pass the DSN like so:

flag.StringVar(&cfg.db.dsn, "db-dsn", os.Getenv("MOVIESDB_DSN"), "PostgreSQL DSN")

And to store the DSN as an environment variable on the local machine, open the .profile file in your HOME directory, and add the DSN like so

export MOVIESDB_DSN='postgres://moviesdb_user:Ch@ng3M3!@localhost/moviesdb'

For our environmental variable to be recognized in the terminal either reboot your system or in the terminal run source $HOME/.profile.

# Make sure the variable is recognized in your terminal.
echo MOVIESDB_DSN

As a bonus you can connect to the database via the DSN saved as the environmental variable

psql $MOVIESDB_DSN

SQL Migrations

To manage SQL migrations we'll be using the migrate command-line tool (which itself is written in Go). To install:

brew install golang-migrate # macOS

# On Linux, simply download the pre-built binary and move it to a location on your system path.
curl -L https://github.com/golang-migrate/migrate/releases/download/v4.18.2/migrate.linux-amd64.tar.gz | tar xvz -C /tmp
mv /tmp/migrate ~/go/bin/
## you may need to add to the path
export PATH=$HOME/go/bin:$PATH

# make sure it's working
migrate -version

Having installed the migrate tool, we can generate our migration files.

migrate create -seq -ext=.sql -dir=./migrations create_movies_table
# -seq flag indicates to use sequential numbering like 0001, 0002 ...
# now we should have two files in the `migrations` directory:
# 001_create_movies_table.up.sql
# 001_create_movies_table.down.sql