Lecture 33

POST and Forms

MCS 275 Spring 2023
Emily Dumas

Lecture 33: POST and Forms

Reminders and announcements:

• Project 4 is due 6pm CDT Friday 28 April.
• Today is the last day to submit initial application for a non-SQLite project 4 topic.

Web app todo list

• ☑ HTML mockup
• ☑ Stylesheet
• ☑ Learn a bit about Flask
• ☑ Database schema & test data
• ☑ Python code to generate worker view HTML from a database query
• ☐ Add page to create new work order
• ☐ Make buttons on worker view page work

Forms

Interactive elements in an HTML document (text entry, checkbox, dropdown list, etc.)

        

            Full name:
            
            Nickname:
            
            
        
    

jsfiddle is a nice way to test out form designs (for code that can be public).

Inputs name vs id

Each form input should have both a name and id attribute. Usually they are equal, but they have separate roles:

• name is what this value is called when submitted to the server.
• id is used to match an input with its <label>.

Textarea

<input type="text"> is typically for single-line answers.

Longer text entry (multi-line) should be handled with a <textarea> tag.

HTTP request types

GET - load a resource, the only action we've considered so far.

GET requests are supposed to be idempotent, meaning repeating the same request multiple times has the same effect as doing it once.

HTTP request types

POST - submit data and/or request an action.

POST requests are not expected to be idempotent. Browsers typically prevent reloading a POST request, for example.

Form values are made available to the function handling submission through flask.request.values.get(name).

Note that a Flask route must explicitly declare that it accepts POST requests:

        from flask import Flask, request

        # ... app setup ...

        @app.route('/registernick',methods = ['POST', 'GET'])
        def record_fullname_and_nickname():
            print("Received nickname {}".format(
                request.values.get("nick")
            ))