Django Framework Fundamentals

1# 🌟 COMPLETE DJANGO BLOG APPLICATION
2# This demonstrates Django MVT architecture with real-world patterns
3
4# models.py - Data Layer
5from django.db import models
6from django.contrib.auth.models import User
7from django.urls import reverse
8from django.utils import timezone
9
10class Category(models.Model):
11    """Blog post categories for organization"""
12    name = models.CharField(max_length=100, unique=True)
13    slug = models.SlugField(max_length=100, unique=True)
14    description = models.TextField(blank=True)
15    created_at = models.DateTimeField(auto_now_add=True)
16
17    class Meta:
18        verbose_name_plural = "Categories"
19        ordering = ['name']
20
21    def __str__(self):
22        return self.name
23
24    def get_absolute_url(self):
25        return reverse('blog:category', kwargs={'slug': self.slug})
26
27class Post(models.Model):
28    """Main blog post model with full functionality"""
29    STATUS_CHOICES = [
30        ('draft', 'Draft'),
31        ('published', 'Published'),
32    ]
33
34    title = models.CharField(max_length=200)
35    slug = models.SlugField(max_length=200, unique=True)
36    author = models.ForeignKey(User, on_delete=models.CASCADE, related_name='blog_posts')
37    category = models.ForeignKey(Category, on_delete=models.SET_NULL, null=True, blank=True)
38    content = models.TextField()
39    excerpt = models.TextField(max_length=300, blank=True)
40    status = models.CharField(max_length=10, choices=STATUS_CHOICES, default='draft')
41    created_at = models.DateTimeField(auto_now_add=True)
42    updated_at = models.DateTimeField(auto_now=True)
43    published_at = models.DateTimeField(blank=True, null=True)
44
45    # SEO and social media fields
46    meta_description = models.CharField(max_length=160, blank=True)
47    featured_image = models.ImageField(upload_to='blog/images/', blank=True, null=True)
48
49    class Meta:
50        ordering = ['-published_at', '-created_at']
51        indexes = [
52            models.Index(fields=['-published_at']),
53            models.Index(fields=['status']),
54        ]
55
56    def __str__(self):
57        return self.title
58
59    def save(self, *args, **kwargs):
60        """Auto-set published_at when status changes to published"""
61        if self.status == 'published' and not self.published_at:
62            self.published_at = timezone.now()
63        super().save(*args, **kwargs)
64
65    def get_absolute_url(self):
66        return reverse('blog:post_detail', kwargs={'slug': self.slug})
67
68    @property
69    def reading_time(self):
70        """Calculate estimated reading time"""
71        words = len(self.content.split())
72        return max(1, words // 200)  # Assume 200 words per minute
73
74class Comment(models.Model):
75    """User comments on blog posts"""
76    post = models.ForeignKey(Post, on_delete=models.CASCADE, related_name='comments')
77    name = models.CharField(max_length=100)
78    email = models.EmailField()
79    content = models.TextField()
80    created_at = models.DateTimeField(auto_now_add=True)
81    is_approved = models.BooleanField(default=False)
82
83    class Meta:
84        ordering = ['created_at']
85
86    def __str__(self):
87        return f'Comment by {self.name} on {self.post.title}'
88
89# views.py - Business Logic Layer
90from django.shortcuts import render, get_object_or_404
91from django.views.generic import ListView, DetailView
92from django.db.models import Q, Count
93from django.core.paginator import Paginator
94from django.http import JsonResponse
95from django.contrib import messages
96
97class PostListView(ListView):
98    """Display paginated list of published blog posts"""
99    model = Post
100    template_name = 'blog/post_list.html'
101    context_object_name = 'posts'
102    paginate_by = 10
103
104    def get_queryset(self):
105        queryset = Post.objects.filter(status='published').select_related('author', 'category')
106
107        # Search functionality
108        search_query = self.request.GET.get('search')
109        if search_query:
110            queryset = queryset.filter(
111                Q(title__icontains=search_query) |
112                Q(content__icontains=search_query)
113            )
114
115        # Category filtering
116        category_slug = self.request.GET.get('category')
117        if category_slug:
118            queryset = queryset.filter(category__slug=category_slug)
119
120        return queryset
121
122    def get_context_data(self, **kwargs):
123        context = super().get_context_data(**kwargs)
124        context['categories'] = Category.objects.annotate(
125            post_count=Count('post', filter=Q(post__status='published'))
126        )
127        context['search_query'] = self.request.GET.get('search', '')
128        return context
129
130class PostDetailView(DetailView):
131    """Display individual blog post with comments"""
132    model = Post
133    template_name = 'blog/post_detail.html'
134    context_object_name = 'post'
135    slug_field = 'slug'
136
137    def get_queryset(self):
138        return Post.objects.filter(status='published').select_related('author', 'category')
139
140    def get_context_data(self, **kwargs):
141        context = super().get_context_data(**kwargs)
142        # Get approved comments
143        context['comments'] = self.object.comments.filter(is_approved=True)
144        # Related posts
145        context['related_posts'] = Post.objects.filter(
146            category=self.object.category,
147            status='published'
148        ).exclude(id=self.object.id)[:3]
149        return context
150
151def category_posts(request, slug):
152    """Display posts filtered by category"""
153    category = get_object_or_404(Category, slug=slug)
154    posts = Post.objects.filter(
155        category=category,
156        status='published'
157    ).select_related('author')
158
159    paginator = Paginator(posts, 10)
160    page_number = request.GET.get('page')
161    page_obj = paginator.get_page(page_number)
162
163    context = {
164        'category': category,
165        'posts': page_obj,
166        'page_obj': page_obj
167    }
168    return render(request, 'blog/category_posts.html', context)
169
170# urls.py - URL Routing
171from django.urls import path
172from . import views
173
174app_name = 'blog'
175
176urlpatterns = [
177    path('', views.PostListView.as_view(), name='post_list'),
178    path('post/<slug:slug>/', views.PostDetailView.as_view(), name='post_detail'),
179    path('category/<slug:slug>/', views.category_posts, name='category'),
180]
181
182# admin.py - Django Admin Configuration
183from django.contrib import admin
184from .models import Category, Post, Comment
185
186@admin.register(Category)
187class CategoryAdmin(admin.ModelAdmin):
188    list_display = ['name', 'slug', 'created_at']
189    prepopulated_fields = {'slug': ('name',)}
190    search_fields = ['name']
191
192@admin.register(Post)
193class PostAdmin(admin.ModelAdmin):
194    list_display = ['title', 'author', 'category', 'status', 'created_at', 'published_at']
195    list_filter = ['status', 'category', 'created_at']
196    search_fields = ['title', 'content']
197    prepopulated_fields = {'slug': ('title',)}
198    date_hierarchy = 'created_at'
199
200    fieldsets = (
201        ('Content', {
202            'fields': ('title', 'slug', 'author', 'category', 'content', 'excerpt')
203        }),
204        ('Publishing', {
205            'fields': ('status', 'published_at')
206        }),
207        ('SEO', {
208            'fields': ('meta_description', 'featured_image'),
209            'classes': ('collapse',)
210        }),
211    )
212
213@admin.register(Comment)
214class CommentAdmin(admin.ModelAdmin):
215    list_display = ['name', 'post', 'created_at', 'is_approved']
216    list_filter = ['is_approved', 'created_at']
217    search_fields = ['name', 'email', 'content']
218    actions = ['approve_comments']
219
220    def approve_comments(self, request, queryset):
221        queryset.update(is_approved=True)
222        messages.success(request, f'{queryset.count()} comments approved.')
223    approve_comments.short_description = "Approve selected comments"
224
225# Template Example: blog/post_list.html
226template_content = '''
227<!-- Base template with Django template language -->
228{% extends 'base.html' %}
229{% load static %}
230
231{% block title %}Blog Posts{% endblock %}
232
233{% block content %}
234<div class="blog-container">
235    <header class="blog-header">
236        <h1>Latest Blog Posts</h1>
237
238        <!-- Search Form -->
239        <form method="get" class="search-form">
240            <input type="text" name="search"
241                   value="{{ search_query }}"
242                   placeholder="Search posts...">
243            <button type="submit">Search</button>
244        </form>
245    </header>
246
247    <!-- Categories Sidebar -->
248    <aside class="categories">
249        <h3>Categories</h3>
250        <ul>
251            {% for category in categories %}
252            <li>
253                <a href="{% url 'blog:category' category.slug %}">
254                    {{ category.name }} ({{ category.post_count }})
255                </a>
256            </li>
257            {% endfor %}
258        </ul>
259    </aside>
260
261    <!-- Posts Grid -->
262    <main class="posts-grid">
263        {% for post in posts %}
264        <article class="post-card">
265            {% if post.featured_image %}
266            <img src="{{ post.featured_image.url }}" alt="{{ post.title }}">
267            {% endif %}
268
269            <div class="post-content">
270                <h2>
271                    <a href="{{ post.get_absolute_url }}">{{ post.title }}</a>
272                </h2>
273
274                <div class="post-meta">
275                    <span>By {{ post.author.get_full_name|default:post.author.username }}</span>
276                    <span>{{ post.published_at|date:"M d, Y" }}</span>
277                    <span>{{ post.reading_time }} min read</span>
278                    {% if post.category %}
279                    <span>in {{ post.category.name }}</span>
280                    {% endif %}
281                </div>
282
283                <p>{{ post.excerpt|default:post.content|truncatewords:30 }}</p>
284
285                <a href="{{ post.get_absolute_url }}" class="read-more">
286                    Read More →
287                </a>
288            </div>
289        </article>
290        {% empty %}
291        <p>No posts found.</p>
292        {% endfor %}
293    </main>
294
295    <!-- Pagination -->
296    {% if is_paginated %}
297    <nav class="pagination">
298        <span class="pagination-info">
299            Page {{ page_obj.number }} of {{ page_obj.paginator.num_pages }}
300        </span>
301
302        {% if page_obj.has_previous %}
303        <a href="?page={{ page_obj.previous_page_number }}">← Previous</a>
304        {% endif %}
305
306        {% if page_obj.has_next %}
307        <a href="?page={{ page_obj.next_page_number }}">Next →</a>
308        {% endif %}
309    </nav>
310    {% endif %}
311</div>
312{% endblock %}
313'''
314
315print("🎉 Django Blog Application Complete!")
316print("\n✅ Features Implemented:")
317print("• MVT Architecture with proper separation")
318print("• Category-based organization")
319print("• Search functionality")
320print("• Pagination with performance optimization")
321print("• SEO-friendly URLs and meta fields")
322print("• Comment system with moderation")
323print("• Django Admin integration")
324print("• Template inheritance")
325print("• Database relationships and indexes")
326print("• Reading time calculation")
327print("\n🚀 Production Ready Features:")
328print("• select_related() for query optimization")
329print("• Database indexes for performance")
330print("• Proper error handling")
331print("• Security best practices")
332print("• Responsive template structure")