Question

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.

Short answer

Create 'meal_planner' folder, start a Django project, make 'meal_plans' app, and create a home page.

Step-by-step solution

Create a New Folder

Open your terminal or command prompt and navigate to the location where you want to create your new folder. Use the command `mkdir meal_planner` to create a new directory called 'meal_planner'. This will be the main directory for your Django project.

Start a New Django Project

Navigate into the newly created 'meal_planner' folder by using the command `cd meal_planner`. Inside this folder, create a new Django project by running `django-admin startproject meal_planner .` (note the dot at the end). This will create a basic Django project structure.

Make a New Django App

With the project directory structure in place, you now need to create a new app within your project. Enter the command `python manage.py startapp meal_plans`. This creates a new Django app called 'meal_plans' in the project folder.

Configure the Project to Include the New App

Open the file 'meal_planner/settings.py' in your text editor and find the `INSTALLED_APPS` list. Add `'meal_plans',` to this list to ensure that your new app is recognized by the Django framework.

Create a Simple Home Page

Inside the 'meal_plans' app folder, open or create a file named 'urls.py'. Define a URL pattern that points to a view: `from django.urls import path from . import views urlpatterns = [ path('', views.home, name='home'), ]`. Then, in 'views.py' within the same folder, create a simple home view: `from django.http import HttpResponse def home(request): return HttpResponse("Welcome to the Meal Planner Home Page")`.

Connect the App URLs to the Project

In 'meal_planner/urls.py', you need to include the URLs from the 'meal_plans' app. Modify the code to: `from django.contrib import admin from django.urls import path, include urlpatterns = [ path('admin/', admin.site.urls), path('', include('meal_plans.urls')), ]`. This tells the project to use the app's URL configurations.

Run the Development Server

Ensure that you're in the 'meal_planner' directory and type the command `python manage.py runserver`. Open a web browser and go to 'http://127.0.0.1:8000/'. You should see the text "Welcome to the Meal Planner Home Page" displayed, indicating your home page is set up correctly.

Key concepts

Django project setup

Setting up a Django project is the foundational step in Django web development and involves creating a structured environment to develop your application. Start by establishing a directory that will house your entire project. It's crucial to navigate your terminal to the desired location on your computer where you'd like your project to reside, using the command `mkdir project_name`. After you have your directory set up, you will initiate a new Django project within it using the `django-admin startproject project_name .` command.

This command creates several files and directories that form the skeleton of a Django project. It includes a manage.py file, which you'll use to perform various Django commands, and another directory named after your project that contains settings and configuration files essential for your application's operation. Remember to maintain proper structure and naming conventions, as these are vital for your project to function correctly.

Creating Django applications

Once your Django project is set up, the next step is to create applications, which are components or sub-modules that make up the project. Each application typically handles a specific functionality or feature within your project. Creating an app is simply done using `python manage.py startapp app_name`, which automatically generates a new directory containing necessary files like views.py, models.py, and an app-specific migrations directory.

In Django, it's important to modularize your application to maintain clean, organized code. After creating the app, you need to integrate it into your project by adding it to the `INSTALLED_APPS` list within your `settings.py` file. This action registers the app with the central Django framework, enabling it to be recognized and interact with other parts of the project seamlessly.

URL routing in Django

In Django, URL routing refers to mapping URL paths to specific view functions or classes in your application. This is a critical infrastructure feature that makes it possible for users to access different parts of your website through their browsers. After creating an app, it’s essential to define URL patterns by editing or creating a `urls.py` file within your app's directory. This file uses Django's `path` and `re_path` functions to connect URL paths with views.

For instance, path configurations route requests to appropriate views, helping you define what should be displayed when a user visits a particular URL. These patterns are then included in the main project’s URL configuration file, typically found in the project directory. This setup is done using `include` function that helps to maintain a clean and organized URL structure.

Django views

Django views are Python functions or classes that take web requests and return web responses, playing a crucial role in generating and displaying content to users. A view can output anything from a simple "Hello World" message to complex data-driven HTML templates. In your application’s `views.py` file, each function or class is a view that deals with a specific URL path.

When a URL is matched in the routing process, its corresponding view function is invoked. This function typically performs any necessary application-specific logic before returning a response, often in the form of a rendered HTML page. Views are the bridge between models and templates in your project, handling user's input and displaying the final content back to them.

Development server in Django

The Django development server is a lightweight web server that comes packaged with Django, allowing developers to test their applications locally. After setting up your project and application, running the development server is as simple as typing `python manage.py runserver` in the terminal from within your project's directory. This command starts the server and listens for incoming HTTP requests on the default port, usually 8000.

Using the development server, you can navigate to `http://127.0.0.1:8000/` in your web browser to see your application in action in a local environment. The server automatically reloads any saved changes, making it highly convenient for testing and development. Note that while the development server is immensely useful in initial phases, it is not designed for production environments.