Login and Sessions

Goal

This snapshot advances Mossbank Post by teaching you to authenticate with signed session cookies.

Every numbered folder is a complete app. Run this stage independently, then compare it with the previous folder.

Prerequisites

Use Go 1.22+, and Docker for Postgres stages.

Port 8083 must be free. Copy .env.example before starting database stages.

• Go toolchain
• A code editor and terminal
• Docker from part 4 onward

Concepts

Keep only the user id in the session and load the user per request.

Keep handlers thin: templates present data, handlers enforce rules, and html/template escapes by default.

Walkthrough

Verify credentials, set the session, and clear it on logout.

Read the example, then open the matching snapshot. The repository includes the surrounding setup and error handling.

session.Set("user_id", user.ID)
session.Save()
c.Redirect(302, "/")

Run and verify

Enter 07-Login-And-Sessions, copy .env.example, and start Gin on port 8083.

Open http://127.0.0.1:8083. Watch the terminal for validation and database errors.

docker compose up -d
git clone https://github.com/michaeldunga1/fcc-gin-blog.git
cd fcc-gin-blog/07-Login-And-Sessions
cp .env.example .env
go run .

Troubleshooting

Changing SESSION_SECRET invalidates cookies.

For database failures, confirm Docker and the mossbank_NN name. Never commit .env.

• Read the first error first
• Restart after environment changes
• Never commit secrets

Try this

Log in, restart, confirm session, then log out.

Test a happy path and one invalid or unauthorized request.

• Make one small change
• Test it in the browser
• Compare with the next snapshot only after it works