[Music] Welcome to Create a Django App. After watching this video, you will be able to: Describe the Django web app structure, and create and run a simple Django web app. Let’s look at a typical Django development process. The order of these steps may vary. First, we create a Django project which is a container for Django apps and settings. Then we create and add one or more Django apps to the project. In Core Development, we create Django models to model the data and create views to determine which data need to be presented to the UI. We also map the request URLs to our views so Django can forward requests to corresponding views via URLs. Then we can start designing and building the UI. Once we are confident of the current version, we can perform unit or system tests. After the core development is done, we need to make our Django app production-ready, using Add-ons such as an admin site or a 3rd party frontend library. Once we have a working Django app, we can deploy it on a web server, either on premise or on cloud, and monitor the server status. A Django project is essentially a Python package that contains all the settings for an instance of Django app. To create a Django project, open a command-line terminal and run `django-admin, startproject, mysite`. This initializes a Django project with related files and folders. You need to know the usage for some core files that Django creates. manage.py is a command-line interface used to interact with the Django project to start the server, migrate models, and so on. settings.py contains the settings and configurations for your Django project. urls.py contains the URL and routing definitions of your Django app. Once you have created the Django project container, you can add your first Django app to it. We’ll call our first app “onlinecourse.” From the mysite project directory, run python, manage.py, startapp, onlinecourse. Django will create a temporary app structure and some important app files. admin.py includes everything you need to create and customize an admin site to manage users and content. models.py contains the data models and ORM. views.py contains view functions and classes to create views. urls.py contains the URL declarations and routing for the app. app.py contains the application configuration class. The migrations folder contains scripts for model migration. Now, we add the `onlinecourse` app we just created to our `mysite` Django project. Open the settings.py file in the mysite folder, find the INSTALLED_APPS list in the settings file, and add a new entry called 'onlinecourse.apps.OnlinecourseConfig` to the list. The OnlinecourseConfig is a configuration class that represents the onlinecourse app. Now that our app is plugged in, we can optionally set up a database for it. The mysite/settings.py file has a DATABASES dictionary to configure the databases for our app. We add a database instance by adding its connection information such as engine, name, username, and password. Once we have set up our app and database, we can define our Django Models as the ORM component between objects and database tables. Let’s define a simple Course model here with fields like name and description. Next, we tell Django we’ve updated the model by running “python, manage.py, makemigrations, onlinecourse.” Django then will create migration scripts under the `migrations` folder. To see more details about the SQL statements for the migration, we could run “python, manage.py, sqlmigrate, onlinecourse 001.” Here, an onlinecourse_course table will be created. Run “python, manage.py, migrate,” to run the migration scripts. Next, we create a simple view and a hard-coded html template to present the course object. Open the onlinecourse/views.py file to add a course_list view function. It accepts an HTTP Request object and returns an HttpResponse object. First, we get the course object from the database as a course object. Then, we create an html template and dynamically insert the course name into the placeholder. Finally, we add the completed html string as the content of the HttpResponse and return it to the UI. Now we associate the course_list view with a URL so Django will route the request URL to the view to be handled. URL routes are defined in a URLConf file for each app as well as for the Django project. To create a URLConf file for onlinecourse app, we first create a urls.py file under onlinecourse/ folder and then add a path object pointing a URL route to the course_list view we created. The first argument of the path constructor is the `route`. It defines URL patterns for Django to parse and match from the HTTP request to a view. Here we leave it as empty, meaning the root URL, host/onlinecourse, will be mapped to our course_list view. Next, we point the root URLConf file of onlinecourse app to the project’s root URLConf file. We open the project’s URLConf file called mysite/urls.py and add a path object referencing the onlinecourse app’s URLConf. So, when Django receives any URLs with the suffix onlinecourse/, it will try to match any URLs in the onlinecourse.urls.py file. And our Django app is set up. Let’s check the result. First, we call the “python, manage.py, runserver” command-line, which will start a development server locally on 127.0.0.1 with default port 8000 for us to host the Django project and app we just created. Once the server starts, we go to the root URL of the online course app. We should see a web page displaying the sentence: “The first course we created is `Cloud Application Development with Database`.” This simple html file is generated by the course_list view function we created earlier. In this video, you learned: The Django project and app structure and key files, A typical Django app development process, and how to create and run a simple Django app.
