Validate input on the server and produce predictable responses
Goal
You should be able to demonstrate the result described in the lesson and explain why each step was necessary.
You should be able to demonstrate the result described in the lesson and explain why each step was necessary.
Step-by-step
01
Define allowed fields
Accept only the fields the form actually needs.
02
Validate and normalize
Check required values, lengths, email formats, and expected enums on the server.
03
Use CSRF protection
For authenticated or state-changing forms, include an anti-CSRF token/nonce appropriate to the framework.
04
Escape output
Validation and output escaping solve different problems; do both.
05
Log failures safely
Record enough to troubleshoot without logging passwords, secrets, or unnecessarily sensitive form content.
Verify before moving on
You should be able to demonstrate the result described in the lesson and explain why each step was necessary.
You should be able to demonstrate the result described in the lesson and explain why each step was necessary.
Troubleshooting
If a command or screen differs from the lesson, stop and verify the version you are using before forcing a change.
What you learned
You now understand the purpose of this part of the system and have a concrete result you can verify before continuing to the next lesson.