Heroku - 10 Heroku postgre part 3

This third part of the Heroku Postgres tutorial picks up where the previous lesson left off: everything is now installed and configured, so we focus on actually creating a table and feeding it from a small Node.js application before deploying that application to Heroku. We use pgAdmin as the external client, since the Heroku Postgres dashboard does not let you modify the database directly: we need a real PostgreSQL tool to do that.

Creating the visits table with pgAdmin

We launch pgAdmin, right-click Servers and choose Create > Server. A dialog asks for the connection details, all of which come from the Heroku Postgres credentials page of the add-on: host, port, database name, username and password. Once the server is added, pgAdmin lists several databases (other tenants on the same Heroku Postgres cluster), but we only have permission on ours — it is the one without a small red cross on its icon.

Inside that database we right-click and create a new table called visit, designed to log one row per visit on the application. We add two columns: an id defined as a serial / auto-incremented integer that serves as the primary key, and a created_at timestamp to know when the visit happened. The table is now ready to receive data.

Building the Node.js app and deploying it

We then create a small Node.js project. npm init -y generates the package.json, after which we install the two required dependencies:

npm install pg
npm install express

In package.json, the start script is set to node app.js so Heroku knows how to launch the application. We create app.js and paste the example code (the focus is not on the code itself): the first part creates an Express server, the second opens the connection to the Postgres database, and the third inserts a row into the visit table on every HTTP request. To deploy, we log in with heroku login, initialize a Git repo with git init, then run git add ., git commit -m "first commit" and finally git push heroku master. Heroku detects the Node.js buildpack, installs every dependency declared in package.json and starts the application. The code is now live and writing visits into the Heroku Postgres database. That is all for this lesson — see you in the next one.