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Solutions - Chapter 18

18-1: New Projects

To get a better idea of what Django does, build a couple empty projects and look at what Django creates. Make a new folder with a simple name, like tik_gram or insta_tok (outside of your learning_log directory), navigate to that folder in a terminal, and create a virtual environment. Install Django and run the command django-admin startproject tg_project . (making sure to include the dot at the end of the command).

Look at the files and folders this command creates, and compare them to Learning Log. Do this a few times, until you’re familiar with what Django creates when starting a new project. Then delete the project directories if you wish.

Note: Early printings of the third edition mention the commmand startproject. That was a holdover from earlier editions; you should use the command django-admin startproject (without the .py), as shown in the main part of the text.

You should see output similar to the following:

(tg_env)tik_gram$ django-admin startproject tg_project .
(tg_env)tik_gram$ ls   tg_project
(tg_env)tik_gram$ ls tg_project

18-2: Short Entries

The __str__() method in the Entry model currently appends an ellipsis to every instance of Entry when Django shows it in the admin site or the shell. Add an if statement to the __str__() method that adds an ellipsis only if the entry is longer than 50 characters. Use the admin site to add an entry that’s fewer than 50 characters in length, and check that it doesn’t have an ellipsis when viewed.
from django.db import models

class Topic(models.Model):

class Entry(models.Model):
    """Something specific learned about a topic."""
    topic = models.ForeignKey(Topic, on_delete=models.CASCADE)
    text = models.TextField()
    date_added = models.DateTimeField(auto_now_add=True)

    class Meta:
        verbose_name_plural = 'entries'

    def __str__(self):
        """Return a simple string representing the entry."""
        if len(self.text) > 50:
            return f"{self.text[:50]}..."
            return self.text

18-4: Pizzeria

Start a new project called pizzeria_project with an app called pizzas. Define a model Pizza with a field called name, which will hold name values, such as Hawaiian and Meat Lovers. Define a model called Topping with fields called pizza and name. The pizza field should be a foreign key to Pizza, and name should be able to hold values such as pineapple, Canadian bacon, and sausage.

Register both models with the admin site, and use the site to enter some pizza names and toppings. Use the shell to explore the data you entered.

An entire Django project, even a small one, is too much to list here. You can see the full solution to this project here.

18-5: Meal Planner

Consider an app that helps people plan their meals throughout the week. Make a new folder called meal_planner, and start a new Django project inside this folder. Then make a new app called meal_plans. Make a simple home page for this project.

The full solution is here.

18-6: Pizzeria Home Page

Add a home page to the Pizzeria project you started in Exercise 18-4 (page 388).

The full solution is here.

18-8: Pizzeria Pages

Add a page to the Pizzeria project from Exercise 18-6 (page 392) that shows the names of available pizzas. Then link each pizza name to a page displaying the pizza’s toppings. Make sure you use template inheritance to build your pages efficiently.

The full solution is here.