Lecture 38
Web app wrap-up
MCS 275 Spring 2022
Emily Dumas
Lecture 38: Web app wrap-up
Course bulletins:
- Work on Project 4.
- Project 4 is due 6pm CDT Friday 29 April
- Autograder (basically QuizBot) opens Monday 25 April.
- Course evaluations open Monday. Please complete!
If GEO strike begins Monday
I hope UIC will avert a strike by reaching an agreement with GEO.
If strike starts on Monday 18 April, then until it ends:
- MCS 275 lectures move online (zoom) to avoid crossing picket line
- MCS 275 labs won't be held
- Homework collected as usual, grading begins when strike ends
- No TA office hours or email
- Instructor availability unchanged (office hours, email, discord)
Today
This is the last in our contiguous lecture series focused on writing a Flask+SQLite application.
(We may revisit this topic a bit in the last week.)
WorkSnap todo list
- ☑ HTML + CSS mockups
- ☑ Database
- ☑ Flask application with worker view
- ☑ New work order form
- ☑ Activate "take assignment" button
- ☐ Activate other buttons
- ☐ Style the submission form
- ☐ Date/time formatting
- ☐ Work order status page
- ☐ Make all actions redirect to natural destinations
- ☐ DB initialization and connection cleanup
- ☐ Detect and handle errors (e.g. failure to take assignment)
WorkSnap todo list
- ☑ HTML + CSS mockups
- ☑ Database
- ☑ Flask application with worker view
- ☑ New work order form
- ☑ Activate "take assignment" button
- ☑ Activate other buttons
- ☑ Style the submission form
- ☐ Date/time formatting
- ☐ Work order status page
- ☐ Make all actions redirect to natural destinations
- ☐ DB initialization and connection cleanup
- ☐ Detect and handle errors (e.g. failure to take assignment)
WorkSnap todo list
- ☑ HTML + CSS mockups
- ☑ Database
- ☑ Flask application with worker view
- ☑ New work order form
- ☑ Activate "take assignment" button
- ☑ Activate other buttons
- ☑ Style the submission form
- ☐ Date/time formatting
- ☐ Work order status page
- ☐ Make all actions redirect to natural destinations
- ☐ DB initialization and connection cleanup
- ☐ Detect and handle errors (e.g. failure to take assignment)
Routes
/worker/<name>/ - (GET) worker's view of orders/wo/new/ - (GET) form for new order/wo/post/ - (POST) form submission destination/wo/<int:woid>/ - (GET) work order status/wo/<int:woid>/assign_to/<name>/ - (GET*) take assignment/wo/<int:woid>/unassign_from/<name>/ - (GET*) unassign/wo/<int:woid>/complete_by/<name>/ - (GET*) mark complete
Did update change anything?
An UPDATE might match any number of rows (e.g. 0, 1, 50). How can we check the actual number?
SELECT changes();
Flask functions
All are in the flask module:
redirect(url) - Returning this object from a route will cause the HTTP server to issue a 302 response code, telling client to load url instead.abort(http_error_code) - Immediately stop and return a HTTP error code (usually 400 bad request, 401 not authorized, 403 forbidden, or 404 not found).
Retrospective
Some of the things you'd do differently in a "real" application:
- Action history: We have a single column for WO creation time. We should probably log every action that changes a work order in a separate table.
- Accounts, roles, cookies: login page checks credentials against DB, sets browser cookie. Auth-required pages check for it, redirect to login page if not found.
- JavaScript: e.g. to check for new messages in real time, post new message without loading a new page, make buttons perform POST requests without forms.
- Pagination: Links to show next/prev page of messages or posts.
References
Revision history
- 2022-04-15 Initial publication