We will go through setting up a Django project from scratch to create a simple polling application. This guide will cover everything from installing Python and Django to configuring your app with models, views, and templates. Along the way, we will build a feature that lets users vote in a poll, and we will explore key concepts like generic views, models, and URL routing. **Step 1: Installing Python and Setting Up a Virtual Environment** Before you start with Django, make sure you have Python installed on your machine. If you don’t have it installed, you can download Python from python.org. To keep your project’s dependencies isolated, it’s best to use a virtual environment. ``` # Install virtualenv if you don't have it pip install virtualenv # Create a virtual environment virtualenv venv # Activate the virtual environment venv\Scripts\activate ``` **Step 2: Installing Django and Starting a Project** With your virtual environment activated, install Django: ``` pip install django ``` Now, create a new Django project called mysite: ``` django-admin startproject mysite ``` This command creates a mysite directory that contains your project files. **Step 3: Creating the Polls App** Django follows a modular approach, and every feature in Django is usually built inside an "app". We will create an app called polls. ``` cd mysite python manage.py startapp polls ``` Next, register the polls app in mysite/settings.py by adding it to the INSTALLED_APPS list: ``` INSTALLED_APPS = [ # other apps... 'polls', ] ``` **Step 4: Defining Models for Questions and Choices** In polls/models.py, we will define two models: Question and Choice. Each Question will have several Choices that users can vote on. ``` from django.db import models from django.utils import timezone import datetime class Question(models.Model): question_text = models.CharField(max_length=200) pub_date = models.DateTimeField('date published') def __str__(self): return self.question_text def was_published_recently(self): now = timezone.now() return now - datetime.timedelta(days=1) <= self.pub_date <= now class Choice(models.Model): question = models.ForeignKey(Question, on_delete=models.CASCADE) choice_text = models.CharField(max_length=200) votes = models.IntegerField(default=0) def __str__(self): return self.choice_text ``` **Step 5: Creating and Migrating the Database** We will be using SQLite for our database, which is the default for Django. The configuration can be found in mysite/settings.py under the DATABASES section: ``` DATABASES = { 'default': { 'ENGINE': 'django.db.backends.sqlite3', 'NAME': BASE_DIR / 'db.sqlite3', } } ``` After setting up the models, you need to generate the migrations and apply them to create the database schema: ``` python manage.py makemigrations python manage.py migrate ``` **Step 6: Creating Views for Polls** We will use Django’s generic views to simplify the process of creating list and detail views. In polls/views.py, define views for listing questions, showing details of a question, and displaying results. ``` from django.shortcuts import get_object_or_404, render from django.http import HttpResponseRedirect from django.urls import reverse from django.db.models import F from django.views import generic from django.utils import timezone from .models import Question, Choice class IndexView(generic.ListView): template_name = 'polls/index.html' context_object_name = 'latest_question_list' def get_queryset(self): return Question.objects.filter(pub_date__lte=timezone.now()).order_by('-pub_date')[:5] class DetailView(generic.DetailView): model = Question template_name = 'polls/detail.html' def get_queryset(self): return Question.objects.filter(pub_date__lte=timezone.now()) class ResultsView(generic.DetailView): model = Question template_name = 'polls/results.html' def vote(request, question_id): question = get_object_or_404(Question, pk=question_id) try: selected_choice = question.choice_set.get(pk=request.POST['choice']) except (KeyError, Choice.DoesNotExist): return render(request, 'polls/detail.html', { 'question': question, 'error_message': "You didn't select a choice.", }) else: selected_choice.votes = F('votes') + 1 selected_choice.save() return HttpResponseRedirect(reverse('polls:results', args=(question.id,))) ``` **Step 7: Mapping URLs to Views** In polls/urls.py, define the URL patterns for our app, which will map the URL paths to the views we just created. ``` from django.urls import path from . import views app_name = 'polls' urlpatterns = [ path('', views.IndexView.as_view(), name='index'), path('/', views.DetailView.as_view(), name='detail'), path('/results/', views.ResultsView.as_view(), name='results'), path('/vote/', views.vote, name='vote'), ] ``` Then, include the polls/urls.py in the main mysite/urls.py: ``` from django.contrib import admin from django.urls import include, path urlpatterns = [ path('polls/', include('polls.urls')), path('admin/', admin.site.urls), ] ``` **Step 8: Creating Templates** In polls/templates/polls/, create the HTML templates. First, index.html will display the list of questions: ``` {% load static %} {% if latest_question_list %}

{{ question.question_text }}

{% else %}

No polls are available.

{% endif %} ``` Next, the detail.html template will display the voting form for a question: ```

{% if error_message %}

{{ error_message }}

{% endif %} ``` Lastly, results.html will display the voting results: ```

{{ choice.choice_text }} -- {{ choice.votes }} vote{{ choice.votes|pluralize }}

Vote again? ``` **Step 9: Running the Development Server** Now that everything is set up, you can start the Django development server: ``` python manage.py runserver ```

{{ question.question_text }}

{{ question.question_text }}

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Building a Simple Polling App in Django: Step-by-Step Guide

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