今日目标

o 理解Django框架的架构和特点

o 掌握Django项目的创建和配置

o 学会使用Django ORM进行数据库操作

o 了解Django的MVT模式

o 掌握Django Admin后台管理

Django框架介绍

Django是一个高级的Python Web框架，具有以下特点：

o 全功能框架：内置ORM、Admin、认证等

o MVT架构：Model-View-Template模式

o 安全性：内置CSRF、XSS等安全防护

o 可扩展性：丰富的第三方包生态

o 快速开发：代码生成和自动化工具

Django vs Flask

# Django特点：全功能、约定优于配置
# Flask特点：轻量级、灵活性高

# Django适合：大型项目、团队开发、快速原型
# Flask适合：小型项目、API服务、学习入门

Django项目创建

1. 安装Django

pip install django
django-admin --version

2. 创建项目

# 创建Django项目
django-admin startproject myproject
cd myproject

# 项目结构
myproject/
├── manage.py
└── myproject/
    ├── __init__.py
    ├── settings.py
    ├── urls.py
    └── wsgi.py

3. 创建应用

# 创建Django应用
python manage.py startapp blog

# 应用结构
blog/
├── __init__.py
├── admin.py
├── apps.py
├── models.py
├── tests.py
├── urls.py
└── views.py

4. 项目配置

# myproject/settings.py
INSTALLED_APPS = [
    'django.contrib.admin',
    'django.contrib.auth',
    'django.contrib.contenttypes',
    'django.contrib.sessions',
    'django.contrib.messages',
    'django.contrib.staticfiles',
    'blog',  # 添加我们的应用
]

# 数据库配置
DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.sqlite3',
        'NAME': BASE_DIR / 'db.sqlite3',
    }
}

# 语言和时区
LANGUAGE_CODE = 'zh-hans'
TIME_ZONE = 'Asia/Shanghai'
USE_I18N = True
USE_TZ = True

Django ORM

1. 模型定义

# blog/models.py
from django.db import models
from django.contrib.auth.models import User

class Category(models.Model):
    """文章分类"""
    name = models.CharField(max_length=100, verbose_name='分类名称')
    description = models.TextField(blank=True, verbose_name='分类描述')
    created_at = models.DateTimeField(auto_now_add=True, verbose_name='创建时间')
    
    class Meta:
        verbose_name = '分类'
        verbose_name_plural = '分类'
        ordering = ['-created_at']
    
    def __str__(self):
        return self.name

class Post(models.Model):
    """文章模型"""
    STATUS_CHOICES = [
        ('draft', '草稿'),
        ('published', '已发布'),
    ]
    
    title = models.CharField(max_length=200, verbose_name='标题')
    slug = models.SlugField(max_length=200, unique=True, verbose_name='URL别名')
    author = models.ForeignKey(User, on_delete=models.CASCADE, verbose_name='作者')
    category = models.ForeignKey(Category, on_delete=models.CASCADE, verbose_name='分类')
    content = models.TextField(verbose_name='内容')
    excerpt = models.TextField(max_length=500, blank=True, verbose_name='摘要')
    status = models.CharField(max_length=10, choices=STATUS_CHOICES, default='draft', verbose_name='状态')
    created_at = models.DateTimeField(auto_now_add=True, verbose_name='创建时间')
    updated_at = models.DateTimeField(auto_now=True, verbose_name='更新时间')
    published_at = models.DateTimeField(null=True, blank=True, verbose_name='发布时间')
    
    class Meta:
        verbose_name = '文章'
        verbose_name_plural = '文章'
        ordering = ['-published_at', '-created_at']
    
    def __str__(self):
        return self.title
    
    def save(self, *args, **kwargs):
        # 自动设置发布时间
        if self.status == 'published' and not self.published_at:
            from django.utils import timezone
            self.published_at = timezone.now()
        super().save(*args, **kwargs)

class Comment(models.Model):
    """评论模型"""
    post = models.ForeignKey(Post, on_delete=models.CASCADE, related_name='comments', verbose_name='文章')
    name = models.CharField(max_length=80, verbose_name='姓名')
    email = models.EmailField(verbose_name='邮箱')
    content = models.TextField(verbose_name='评论内容')
    created_at = models.DateTimeField(auto_now_add=True, verbose_name='评论时间')
    active = models.BooleanField(default=True, verbose_name='是否显示')
    
    class Meta:
        verbose_name = '评论'
        verbose_name_plural = '评论'
        ordering = ['-created_at']
    
    def __str__(self):
        return f'评论 by {self.name} on {self.post}'

2. 数据库迁移

# 创建迁移文件
python manage.py makemigrations

# 执行迁移
python manage.py migrate

# 查看迁移状态
python manage.py showmigrations

3. ORM查询

# blog/views.py
from django.shortcuts import render, get_object_or_404
from django.core.paginator import Paginator
from .models import Post, Category, Comment

def post_list(request):
    """文章列表"""
    # 基本查询
    posts = Post.objects.filter(status='published')
    
    # 关联查询
    posts = Post.objects.select_related('author', 'category').filter(status='published')
    
    # 聚合查询
    from django.db.models import Count
    categories = Category.objects.annotate(post_count=Count('post'))
    
    # 分页
    paginator = Paginator(posts, 10)
    page_number = request.GET.get('page')
    page_obj = paginator.get_page(page_number)
    
    context = {
        'page_obj': page_obj,
        'categories': categories,
    }
    return render(request, 'blog/post_list.html', context)

def post_detail(request, slug):
    """文章详情"""
    post = get_object_or_404(Post, slug=slug, status='published')
    
    # 获取评论
    comments = post.comments.filter(active=True)
    
    # 获取相关文章
    related_posts = Post.objects.filter(
        category=post.category,
        status='published'
    ).exclude(id=post.id)[:3]
    
    context = {
        'post': post,
        'comments': comments,
        'related_posts': related_posts,
    }
    return render(request, 'blog/post_detail.html', context)

def category_posts(request, category_slug):
    """分类文章"""
    category = get_object_or_404(Category, slug=category_slug)
    posts = Post.objects.filter(category=category, status='published')
    
    paginator = Paginator(posts, 10)
    page_number = request.GET.get('page')
    page_obj = paginator.get_page(page_number)
    
    context = {
        'category': category,
        'page_obj': page_obj,
    }
    return render(request, 'blog/category_posts.html', context)

Django Admin

1. 创建超级用户

python manage.py createsuperuser

2. 注册模型

# blog/admin.py
from django.contrib import admin
from .models import Category, Post, Comment

@admin.register(Category)
class CategoryAdmin(admin.ModelAdmin):
    list_display = ['name', 'description', 'created_at']
    search_fields = ['name']
    list_filter = ['created_at']

@admin.register(Post)
class PostAdmin(admin.ModelAdmin):
    list_display = ['title', 'author', 'category', 'status', 'created_at', 'published_at']
    list_filter = ['status', 'created_at', 'published_at', 'category', 'author']
    search_fields = ['title', 'content']
    prepopulated_fields = {'slug': ('title',)}
    raw_id_fields = ['author']
    date_hierarchy = 'published_at'
    ordering = ['status', '-published_at']
    
    fieldsets = (
        ('基本信息', {
            'fields': ('title', 'slug', 'author', 'category')
        }),
        ('内容', {
            'fields': ('content', 'excerpt')
        }),
        ('发布信息', {
            'fields': ('status', 'published_at'),
            'classes': ('collapse',)
        }),
    )

@admin.register(Comment)
class CommentAdmin(admin.ModelAdmin):
    list_display = ['name', 'post', 'created_at', 'active']
    list_filter = ['active', 'created_at']
    search_fields = ['name', 'email', 'content']
    actions = ['approve_comments', 'disapprove_comments']
    
    def approve_comments(self, request, queryset):
        queryset.update(active=True)
    approve_comments.short_description = "批准选中的评论"
    
    def disapprove_comments(self, request, queryset):
        queryset.update(active=False)
    disapprove_comments.short_description = "拒绝选中的评论"

URL配置

1. 项目URL配置

# myproject/urls.py
from django.contrib import admin
from django.urls import path, include
from django.conf import settings
from django.conf.urls.static import static

urlpatterns = [
    path('admin/', admin.site.urls),
    path('blog/', include('blog.urls')),
    path('', include('blog.urls')),  # 根URL
] + static(settings.MEDIA_URL, document_root=settings.MEDIA_ROOT)

2. 应用URL配置

# blog/urls.py
from django.urls import path
from . import views

app_name = 'blog'

urlpatterns = [
    path('', views.post_list, name='post_list'),
    path('post/<slug:slug>/', views.post_detail, name='post_detail'),
    path('category/<slug:category_slug>/', views.category_posts, name='category_posts'),
    path('search/', views.post_search, name='post_search'),
]

视图和模板

1. 基于函数的视图

# blog/views.py
from django.shortcuts import render, get_object_or_404, redirect
from django.contrib.auth.decorators import login_required
from django.contrib import messages
from .models import Post, Comment
from .forms import CommentForm

def post_search(request):
    """文章搜索"""
    query = request.GET.get('q', '')
    results = []
    
    if query:
        results = Post.objects.filter(
            models.Q(title__icontains=query) |
            models.Q(content__icontains=query),
            status='published'
        )
    
    context = {
        'query': query,
        'results': results,
    }
    return render(request, 'blog/search.html', context)

@login_required
def add_comment(request, post_id):
    """添加评论"""
    post = get_object_or_404(Post, id=post_id, status='published')
    
    if request.method == 'POST':
        form = CommentForm(request.POST)
        if form.is_valid():
            comment = form.save(commit=False)
            comment.post = post
            comment.save()
            messages.success(request, '评论添加成功！')
            return redirect('blog:post_detail', slug=post.slug)
    else:
        form = CommentForm()
    
    context = {
        'post': post,
        'form': form,
    }
    return render(request, 'blog/add_comment.html', context)

2. 基于类的视图

# blog/views.py
from django.views.generic import ListView, DetailView, CreateView, UpdateView, DeleteView
from django.contrib.auth.mixins import LoginRequiredMixin, UserPassesTestMixin
from django.urls import reverse_lazy

class PostListView(ListView):
    """文章列表视图"""
    model = Post
    template_name = 'blog/post_list.html'
    context_object_name = 'posts'
    paginate_by = 10
    
    def get_queryset(self):
        return Post.objects.filter(status='published').select_related('author', 'category')
    
    def get_context_data(self, **kwargs):
        context = super().get_context_data(**kwargs)
        context['categories'] = Category.objects.annotate(
            post_count=Count('post')
        )
        return context

class PostDetailView(DetailView):
    """文章详情视图"""
    model = Post
    template_name = 'blog/post_detail.html'
    context_object_name = 'post'
    
    def get_queryset(self):
        return Post.objects.filter(status='published')
    
    def get_context_data(self, **kwargs):
        context = super().get_context_data(**kwargs)
        context['comments'] = self.object.comments.filter(active=True)
        context['related_posts'] = Post.objects.filter(
            category=self.object.category,
            status='published'
        ).exclude(id=self.object.id)[:3]
        return context

class PostCreateView(LoginRequiredMixin, CreateView):
    """创建文章视图"""
    model = Post
    template_name = 'blog/post_form.html'
    fields = ['title', 'content', 'category', 'excerpt', 'status']
    
    def form_valid(self, form):
        form.instance.author = self.request.user
        return super().form_valid(form)
    
    def get_success_url(self):
        return reverse_lazy('blog:post_detail', kwargs={'slug': self.object.slug})

class PostUpdateView(LoginRequiredMixin, UserPassesTestMixin, UpdateView):
    """更新文章视图"""
    model = Post
    template_name = 'blog/post_form.html'
    fields = ['title', 'content', 'category', 'excerpt', 'status']
    
    def test_func(self):
        post = self.get_object()
        return self.request.user == post.author
    
    def get_success_url(self):
        return reverse_lazy('blog:post_detail', kwargs={'slug': self.object.slug})

class PostDeleteView(LoginRequiredMixin, UserPassesTestMixin, DeleteView):
    """删除文章视图"""
    model = Post
    template_name = 'blog/post_confirm_delete.html'
    success_url = reverse_lazy('blog:post_list')
    
    def test_func(self):
        post = self.get_object()
        return self.request.user == post.author

3. 模板系统

<!-- templates/base.html -->
<!DOCTYPE html>
<html lang="zh-CN">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>{% block title %}我的博客{% endblock %}</title>
    <link href="https://cdn.jsdelivr.net/npm/bootstrap@5.1.3/dist/css/bootstrap.min.css" rel="stylesheet">
    {% load static %}
    <link rel="stylesheet" href="{% static 'css/style.css' %}">
</head>
<body>
    <nav class="navbar navbar-expand-lg navbar-dark bg-dark">
        <div class="container">
            <a class="navbar-brand" href="{% url 'blog:post_list' %}">我的博客</a>
            <div class="navbar-nav">
                <a class="nav-link" href="{% url 'blog:post_list' %}">首页</a>
                {% if user.is_authenticated %}
                    <a class="nav-link" href="{% url 'blog:post_create' %}">写文章</a>
                    <a class="nav-link" href="{% url 'logout' %}">退出</a>
                {% else %}
                    <a class="nav-link" href="{% url 'login' %}">登录</a>
                {% endif %}
            </div>
        </div>
    </nav>

    <main class="container mt-4">
        {% if messages %}
            {% for message in messages %}
                <div class="alert alert-{{ message.tags }}">
                    {{ message }}
                </div>
            {% endfor %}
        {% endif %}

        {% block content %}{% endblock %}
    </main>

    <footer class="bg-dark text-white text-center py-3 mt-5">
        <p>(c) 2024 我的博客</p>
    </footer>

    <script src="https://cdn.jsdelivr.net/npm/bootstrap@5.1.3/dist/js/bootstrap.bundle.min.js"></script>
</body>
</html>

<!-- templates/blog/post_list.html -->
{% extends 'base.html' %}

{% block title %}文章列表{% endblock %}

{% block content %}
<div class="row">
    <div class="col-md-8">
        <h1>最新文章</h1>
        
        {% for post in page_obj %}
        <article class="card mb-4">
            <div class="card-body">
                <h2 class="card-title">
                    <a href="{% url 'blog:post_detail' post.slug %}" class="text-decoration-none">
                        {{ post.title }}
                    </a>
                </h2>
                <p class="card-text text-muted">
                    作者: {{ post.author.username }} | 
                    分类: {{ post.category.name }} | 
                    发布时间: {{ post.published_at|date:"Y-m-d H:i" }}
                </p>
                <p class="card-text">{{ post.excerpt|default:post.content|truncatewords:30 }}</p>
                <a href="{% url 'blog:post_detail' post.slug %}" class="btn btn-primary">阅读更多</a>
            </div>
        </article>
        {% empty %}
        <p>暂无文章</p>
        {% endfor %}

        <!-- 分页 -->
        {% if page_obj.has_other_pages %}
        <nav>
            <ul class="pagination">
                {% if page_obj.has_previous %}
                    <li class="page-item">
                        <a class="page-link" href="?page={{ page_obj.previous_page_number }}">上一页</a>
                    </li>
                {% endif %}

                {% for num in page_obj.paginator.page_range %}
                    {% if page_obj.number == num %}
                        <li class="page-item active">
                            <span class="page-link">{{ num }}</span>
                        </li>
                    {% elif num > page_obj.number|add:'-3' and num < page_obj.number|add:'3' %}
                        <li class="page-item">
                            <a class="page-link" href="?page={{ num }}">{{ num }}</a>
                        </li>
                    {% endif %}
                {% endfor %}

                {% if page_obj.has_next %}
                    <li class="page-item">
                        <a class="page-link" href="?page={{ page_obj.next_page_number }}">下一页</a>
                    </li>
                {% endif %}
            </ul>
        </nav>
        {% endif %}
    </div>

    <div class="col-md-4">
        <div class="card">
            <div class="card-header">
                <h5>分类</h5>
            </div>
            <div class="card-body">
                <ul class="list-unstyled">
                    {% for category in categories %}
                    <li>
                        <a href="{% url 'blog:category_posts' category.slug %}" class="text-decoration-none">
                            {{ category.name }} ({{ category.post_count }})
                        </a>
                    </li>
                    {% endfor %}
                </ul>
            </div>
        </div>
    </div>
</div>
{% endblock %}

表单处理

1. 表单定义

# blog/forms.py
from django import forms
from .models import Comment

class CommentForm(forms.ModelForm):
    class Meta:
        model = Comment
        fields = ['name', 'email', 'content']
        widgets = {
            'name': forms.TextInput(attrs={'class': 'form-control'}),
            'email': forms.EmailInput(attrs={'class': 'form-control'}),
            'content': forms.Textarea(attrs={'class': 'form-control', 'rows': 4}),
        }

class PostForm(forms.ModelForm):
    class Meta:
        model = Post
        fields = ['title', 'content', 'category', 'excerpt', 'status']
        widgets = {
            'title': forms.TextInput(attrs={'class': 'form-control'}),
            'content': forms.Textarea(attrs={'class': 'form-control', 'rows': 10}),
            'category': forms.Select(attrs={'class': 'form-control'}),
            'excerpt': forms.Textarea(attrs={'class': 'form-control', 'rows': 3}),
            'status': forms.Select(attrs={'class': 'form-control'}),
        }

2. 表单模板

<!-- templates/blog/post_form.html -->
{% extends 'base.html' %}

{% block title %}
    {% if form.instance.pk %}编辑文章{% else %}写文章{% endif %}
{% endblock %}

{% block content %}
<div class="row justify-content-center">
    <div class="col-md-8">
        <h1>{% if form.instance.pk %}编辑文章{% else %}写文章{% endif %}</h1>
        
        <form method="post">
            {% csrf_token %}
            
            {% for field in form %}
            <div class="mb-3">
                <label for="{{ field.id_for_label }}" class="form-label">
                    {{ field.label }}
                </label>
                {{ field }}
                {% if field.help_text %}
                    <div class="form-text">{{ field.help_text }}</div>
                {% endif %}
                {% if field.errors %}
                    {% for error in field.errors %}
                        <div class="text-danger">{{ error }}</div>
                    {% endfor %}
                {% endif %}
            </div>
            {% endfor %}
            
            <button type="submit" class="btn btn-primary">
                {% if form.instance.pk %}更新{% else %}发布{% endif %}
            </button>
            <a href="{% url 'blog:post_list' %}" class="btn btn-secondary">取消</a>
        </form>
    </div>
</div>
{% endblock %}

用户认证

1. 认证视图

# blog/views.py
from django.contrib.auth import login, logout
from django.contrib.auth.forms import UserCreationForm, AuthenticationForm
from django.shortcuts import render, redirect

def register(request):
    """用户注册"""
    if request.method == 'POST':
        form = UserCreationForm(request.POST)
        if form.is_valid():
            user = form.save()
            login(request, user)
            messages.success(request, '注册成功！')
            return redirect('blog:post_list')
    else:
        form = UserCreationForm()
    
    return render(request, 'registration/register.html', {'form': form})

def user_login(request):
    """用户登录"""
    if request.method == 'POST':
        form = AuthenticationForm(request, data=request.POST)
        if form.is_valid():
            user = form.get_user()
            login(request, user)
            messages.success(request, f'欢迎回来，{user.username}！')
            return redirect('blog:post_list')
    else:
        form = AuthenticationForm()
    
    return render(request, 'registration/login.html', {'form': form})

def user_logout(request):
    """用户退出"""
    logout(request)
    messages.info(request, '您已成功退出。')
    return redirect('blog:post_list')

2. 认证URL配置

# myproject/urls.py
from django.contrib.auth import views as auth_views

urlpatterns = [
    # ... 其他URL配置
    path('accounts/login/', auth_views.LoginView.as_view(), name='login'),
    path('accounts/logout/', auth_views.LogoutView.as_view(), name='logout'),
    path('accounts/register/', views.register, name='register'),
]

静态文件管理

1. 静态文件配置

# settings.py
STATIC_URL = '/static/'
STATICFILES_DIRS = [
    BASE_DIR / 'static',
]
STATIC_ROOT = BASE_DIR / 'staticfiles'

MEDIA_URL = '/media/'
MEDIA_ROOT = BASE_DIR / 'media'

2. 收集静态文件

python manage.py collectstatic

今日总结

今天我们学习了Django框架的核心知识：

1. Django项目结构：项目创建、应用配置、URL路由

2. Django ORM：模型定义、数据库迁移、查询操作

3. Django Admin：后台管理、模型注册、自定义管理界面

4. 视图系统：基于函数的视图、基于类的视图

5. 模板系统：模板继承、模板标签、模板过滤器

6. 表单处理：表单定义、表单验证、CSRF保护

7. 用户认证：用户注册、登录、权限控制

Django是一个功能强大的Web框架，适合构建大型的Web应用。

练习建议

1. 创建一个完整的博客系统

2. 实现用户注册和登录功能

3. 开发一个简单的电商网站

4. 创建一个内容管理系统