In this chapter we’ll build a new Django project that says “Hello, World” on the homepage. This is the traditional way to start a new programming language or framework. We’ll also work with git for the first time which is a version control system and deploy our code to Bitbucket, a remote code repository.

Initial Setup

To start navigate to a new directory on your computer. For example, we can create a helloworld folder on the Desktop with the following commands.

$ cd ~/Desktop
$ mkdir helloworld
$ cd helloworld

Make sure you’re not already in an existing virtual environment at this point. If you see text in parentheses () before the dollar sign $ then you are. To exit it, type exit and hit Return. The parentheses should disappear which means that virtual environment is no longer active.

We’ll use pipenv to create a new virtual environment, install Django and then activate it.

$ pipenv install django
$ pipenv shell

If you are on a Mac you should see parentheses now at the beginning of your command line prompt in the form (helloworld-XXX) where XXX represents random characters. On my computer I see (helloworld-415ivvZC). I’ll display (helloworld) here in the text but you will see something slightly different on your computer. If you are on Windows you will not see a visual prompt at this time.

Create a new Django project called helloworld_project making sure to include the period . at the end of the command so that it is installed in our current directory.

(helloworld) $ django-admin startproject helloworld_project .

If you use the tree command you can see what our Django project structure now looks like. (Note: If tree doesn’t work for you, install it with Homebrew: brew install tree.)

(helloworld) $ tree
.
├── helloworld_project
│   ├── __init__.py
│   ├── settings.py
│   ├── urls.py
│   └── wsgi.py
└── manage.py

1 directory, 5 files

The settings.py file controls our project’s settings, urls.py tells Django which pages to build in response to a browser or url request, and wsgi.py, which stands for web server gateway interface, helps Django serve our eventual web pages. The last file manage.py is used to execute various Django commands such as running the local web server or creating a new app.

Django comes with a built-in web server for local development purposes. We can start it with the runserver command.

(helloworld) $ python manage.py runserver

If you visit http://127.0.0.1:8000/ you should see our familiar Django welcome page.

Django welcome page

Create an app

Django uses the concept of projects and apps to keep code clean and readable. A single Django project contains one or more apps within it that all work together to power a web application. This is why the command for a new Django project is startproject! For example, a real-world Django e-commerce site might have one app for user authentication, another app for payments, and a third app to power item listing details. Each focuses on an isolated piece of functionality.

We need to create our first app which we’ll call pages. From the command line, quit the server with Control+c. Then use the startapp command.

(helloworld) $ python manage.py startapp pages

If you look again inside the directory with the tree command you’ll see Django has created a pages directory with the following files:

├── pages
│   ├── __init__.py
│   ├── admin.py
│   ├── apps.py
│   ├── migrations
│   │   └── __init__.py
│   ├── models.py
│   ├── tests.py
│   └── views.py

Let’s review what each new pages app file does:

  • admin.py is a configuration file for the built-in Django Admin app
  • apps.py is a configuration file for the app itself
  • migrations/ keeps track of any changes to our models.py file so our database and models.py stay in sync
  • models.py is where we define our database models, which Django automatically translates into database tables
  • tests.py is for our app-specific tests
  • views.py is where we handle the request/response logic for our web app

Even though our new app exists within the Django project, Django doesn’t “know” about it until we explicitly add it. In your text editor open the settings.py file and scroll down to INSTALLED_APPS where you’ll see six built-in Django apps already there. Add our new pages app at the bottom:

# helloworld_project/settings.py
INSTALLED_APPS = [
    'django.contrib.admin',
    'django.contrib.auth',
    'django.contrib.contenttypes',
    'django.contrib.sessions',
    'django.contrib.messages',
    'django.contrib.staticfiles',
    'pages', # new
]

Views and URLConfs

In Django, Views determine what content is displayed on a given page while URLConfs determine where that content is going.

When a user requests a specific page, like the homepage, the URLConf uses a regular expression to map that request to the appropriate view function which then returns the correct data.

In other words, our view will output the text “Hello, World” while our url will ensure that when the user visits the homepage they are redirected to the correct view.

Let’s start by updating the views.py file in our pages app to look as follows:

# pages/views.py
from django.http import HttpResponse


def homePageView(request):
    return HttpResponse('Hello, World!')

Basically we’re saying whenever the view function homePageView is called, return the text “Hello, World!” More specifically, we’ve imported the built-in HttpResponse method so we can return a response object to the user. Our function homePageView accepts the request object and returns a response with the string Hello, World!.

Now we need to configure our urls. Within the pages app, create a new urls.py file.

(helloworld) $ touch pages/urls.py

Then update it with the following code:

# pages/urls.py
from django.urls import path

from . import views

urlpatterns = [
    path('', views.homePageView, name='home')
]

On the top line we import path from Django to power our urlpattern and on the next line we import our views. The period used here from . import views means reference the current directory, which is our pages app containing both views.py and urls.py. Our urlpattern has three parts:

  • a Python regular expression for the empty string ''
  • specify the view which is called homePageView
  • add an optional url name of 'home'

In other words, if the user requests the homepage, represented by the empty string '' then use the view called homePageView.

We’re almost done. The last step is to configure our project-level urls.py file too. Remember that it’s common to have multiple apps within a single Django project, so they each need their own route.

Update the helloworld_project/urls.py file as follows:

# helloworld_project/urls.py
from django.contrib import admin
from django.urls import path, include

urlpatterns = [
    path('admin/', admin.site.urls),
    path('', include('pages.urls')),
]

We’ve imported include on the second line next to path and then created a new urlpattern for our pages app. Now whenever a user visits the homepage at / they will first be routed to the pages app and then to the homePageView view.

It’s often confusing to beginners that we don’t need to import the pages app here, yet we refer to it in our urlpattern as pages.urls. The reason we do it this way is that that the method django.urls.include() expects us to pass in a module, or app, as the first argument. So without using include we would need to import our pages app, but since we do use include we don’t have to at the project level!

Hello, world!

We have all the code we need now! To confirm everything works as expected, restart our Django server:

(helloworld) $ python manage.py runserver

If you refresh the browser for http://127.0.0.1:8000/ it now displays the text “Hello, world!”

Hello world homepage

Git

In the previous chapter we also installed git which is a version control system. Let’s use it here. The first step is to initialize (or add) git to our repository.

(helloworld) $ git init

If you then type git status you’ll see a list of changes since the last git commit. Since this is our first commit, this list is all of our changes so far.

(helloworld) $ git status
On branch master

No commits yet

Untracked files:
  (use "git add <file>..." to include in what will be committed)

        db.sqlite3
        helloworld_project/
        manage.py
        pages/
        Pipfile
        Pipfile.lock

nothing added to commit but untracked files present (use "git add" to track)

We next want to add all changes by using the command add -A and then commit the changes along with a message describing what has changed.

(helloworld) $ git add -A
(helloworld) $ git commit -m 'initial commit'

Please note Windows users may receive an error git commit error: pathspec ‘commit’ did not match any file(s) known to git which appears to be related to using single quotes '' as opposed to double quotes "". If you see this error, using double quotes for all commit messages going forward.

Bitbucket

It’s a good habit to create a remote repository of your code for each project. This way you have a backup in case anything happens to your computer and more importantly, it allows for collaboration with other software developers. The two most popular choices are Bitbucket and Github.

In this book we will use Bitbucket because it allows private repositories for free. Github charges a fee. Public repositories are available for anyone on the internet to use; private repositories are not. When you’re learning web development, it’s best to stick to private repositories so you don’t inadvertently post critical information such as passwords online.

To get started on Bitbucket, sign up for a free account. After confirming your account via email you’ll be redirected to the Bitbucket welcome page. Click on the link for “Create a repository”.

Bitbucket welcome page

Then on the “Create Repo” page enter in the name of your repository: “hello-world”. Then click the blue “Create repository button”:

Bitbucket create repo

On the next page, click on the link on the bottom for “I have an existing project” which will open a dropdown:

Bitbucket existing project

We’re already in the directory for our repo so skip Step 1. In Step 2, we’ll use two commands to add our project to Bitbucket. Note that your command will differ from mine since you have a different username. The general format is the below where <USER> is your Bitbucket username.

(helloworld) $ git remote add origin https://<USER>@bitbucket.org/<USER>/hello-world.git

After running this command to configure git with this Bitbucket repository, we must “push” our code into it.

(helloworld) $ git push -u origin master

Now if you go back to your Bitbucket page and refresh it, you’ll see the code is now online! Click on the “Source” tab on the left to see it all.

Bitbucket overview

Since we’re done, go ahead and exit our virtual environment with the exit command.

(helloworld) $ exit

You should now see no parentheses on your command line, indicating the virtual environment is no longer active.

Conclusion

Congratulations! We’ve covered a lot of fundamental concepts in this chapter. We built our first Django application and learned about Django’s project/app structure. We started to learn about views, urls, and the internal web server. And we worked with git to track our changes and pushed our code into a private repo on Bitbucket.

Continue on to Chapter 3: Pages app where we’ll build and deploy a more complex Django application using templates and class-based views.