Homework 3

Due: Thursday April 23, 11pm

Submission: Submit it to this CrowdGrader assignment

The Assignment

You need to add a delete button to each row of the products table displayed in lecture_form, and you have to allow the table to be sorted according to product price. The details follow below.

Starter Code

First, make sure you have the most recent py4web:

cd py4web

git checkout master

git pull

The starter code is in the homework 3 branch of the lecture form, which you can get into an app called hw3 as follows:

cd apps

git clone https://luca_de_alfaro@bitbucket.org/luca_de_alfaro/lecture_form.git hw3

cd hw3

git checkout homework3

Adding a Delete Button

The index controller (at path /index) displays a table of products. On each row of the table, there is already an "Edit" button. You need to add a "Delete" button, complete with a delete icon, that:

• Immediately deletes the item from the products;
• Redirects to /index.

The effect is that when you press the button, the deletion will happen, and the the table will be redisplayed minus the row you have deleted.

The button URL needs to be signed, because it carries out an action that has an effect; you can look in the button_implementation at how to create a signer, and sign a URL. How to delete records in a database is documented in the PyDAL - database abstraction layer documentation (it is a good idea for you to become familiar with this documentation).

Allowing the Table To Be Sorted By Cost

Your next task is to allow the table to be sorted by cost. The behavior needs to be as follows:

• Initially, when the column is unsorted, you display the icon sort next to the Product Cost table, as is done in the starter code.
• When you click on either the icon, or the "Product Cost" (that is, when you click on the table header for the Product Cost), you sort the items in ascending order of cost, and you replace the icon with sort-asc.
• When you click again on the header, you sort the items in descending order of cost, and you replace the icon with sort-desc.
• When you click again, you sould sort the items in ascending order, again with icon sort-asc, and so forth.

To obtain this behavior, you should use the following URLs:

• /index displays the unsorted products
• /index?sort=asc displays the products sorted in ascending order
• /index?sort=desc displays the products sorted in descending order

To sort the products, you should use the orderby construct of PyDAL.