Django入门项目实践（中）

4.用户账户

4.1 让用户能够输入数据

添加新主题

# untitled/learning_logs/forms.py
from django import forms

from .models import Topic, Entry

class TopicForm(forms.ModelForm):
    class Meta:
        model = Topic
        fields = ['text']
        labels = {'text':''}

"""定义learning_logs的URL模式"""
# untitled/learning_logs/urls.py
from django.conf.urls import url

from . import views

app_name = 'learning_logs'

urlpatterns = [
    # 主页
    url(r'^$', views.index, name='index'),
    url(r'^topics/$', views.topics, name='topics'),
    url(r'^topics/(?P<topic_id>\d+)/$', views.topic, name='topic'),
    url(r'^new_topic/$', views.new_topic, name='new_topic'),
]

# untitled/learning_logs/views.py
from django.http import HttpResponseRedirect
from django.shortcuts import render
from django.urls import reverse

from learning_logs.forms import TopicForm
from learning_logs.models import Topic

#···

def new_topic(request):
    """添加新主题"""
    if request.method != 'POST':
        form = TopicForm()
    else:
        form = TopicForm(request.POST)
        if form.is_valid():
            form.save()
            return HttpResponseRedirect(reverse('learning_logs:topics'))

    context = {'form':form}
    return render(request, 'learning_logs/new_topic.html', context)

#···

<!-- untitled/templates/learning_logs/new_topic.html -->
{% extends "learning_logs/base.html" %}

{% block content %}
  <p>Add a new topic:</p>

  <form action="{% url 'learning_logs:new_topic' %}" method='post'>
    {% csrf_token %}
    {{ form.as_p }}
    <button name="submit">add topic</button>
  </form>
    
{% endblock content %}

添加新条目
（略）
编辑新条目
（略）

4.2 创建用户账户

应用程序users

# untitled/untitled/settings.py
# ···
INSTALLED_APPS = [
    'django.contrib.admin',
    'django.contrib.auth',
    'django.contrib.contenttypes',
    'django.contrib.sessions',
    'django.contrib.messages',
    'django.contrib.staticfiles',

    # 我的应用程序
    'learning_logs',
    'users'
]

# ···

# untitled/untitled/urls.py
from django.contrib import admin
from django.urls import path
from django.conf.urls import include, url

urlpatterns = [
    path('admin/', admin.site.urls),
    url(r'^users/', include('users.urls', namespace='users')),
    url(r'', include('learning_logs.urls', namespace='learning_logs')),
]

4.2.1 登录

由于Django版本的问题，下面的URL模式跟《Python编程从入门到实践》的示例有点不一样。

"""为应用程序users定义URL模式"""
# untitled/users/urls.py
from django.contrib.auth.views import LoginView
from django.urls import path

app_name = 'users'

urlpatterns = [
    path('login/', LoginView.as_view(template_name='users/login.html'), name="login"),
]

<!-- untitled/templates/users/login.html -->
{% extends "learning_logs/base.html" %}

{% block content %}

  {% if form.errors %}
  <p>Your username and password didn't match. Please try again.</p>
  {% endif %}
    
  <form method="post" action="{% url 'users:login' %}">
  {% csrf_token %}
  {{ form.as_p }}
    
  <button name="submit">log in</button>
  <input type="hidden" name="next" value="{% url 'learning_logs:index' %}" />
  </form>
    
{% endblock content %}

<!-- untitled/templates/learning_logs/base.html -->
<p>
  <a href="{% url 'learning_logs:index' %}">Learning Log</a> -
  <a href="{% url 'learning_logs:topics' %}">Topics</a> - 
  {% if user.is_authenticated %}
    Hello, {{ user.username }}.
  {% else %}
    <a href="{% url 'users:login' %}">log in</a>
  {% endif %}
</p>

{% block content %}{% endblock %}

4.2.2 注销

# untitled/users/urls.py
from django.contrib.auth.views import LoginView
from django.urls import path
from django.conf.urls import url

from . import views

app_name = 'users'

urlpatterns = [
    path('login/', LoginView.as_view(template_name='users/login.html'), name="login"),
    url(r'^logout/$', views.logout_view, name='logout'),
]

注意下面导入的是from django.urls import reverse，而不是from django.core.urlresolvers import reverse。

# untitled/users/views.py
from django.http import HttpResponseRedirect
from django.urls import reverse
from django.contrib.auth import logout


def logout_view(request):
    """Log the user out."""
    logout(request)
    return HttpResponseRedirect(reverse('learning_logs:index'))

4.2.3 注册

# untitled/users/views.py
from django.contrib.auth.forms import UserCreationForm
from django.http import HttpResponseRedirect
from django.shortcuts import render
from django.urls import reverse
from django.contrib.auth import logout, authenticate, login

# ···

def register(request):
    if request.method != 'POST':
        form = UserCreationForm()
    else:
        form = UserCreationForm(data=request.POST)

        if form.is_valid():
            new_user = form.save()
            authenticated_user = authenticate(username=new_user.username, password=request.POST['password1'])
            login(request, authenticated_user)
            return HttpResponseRedirect(reverse('learning_logs:index'))

    context = {'form':form}
    return render(request, "users/register.html", context)

<!-- untitled/templates/users/register.html -->
{% extends "learning_logs/base.html" %}

{% block content %}

  <form method="post" action="{% url 'users:register' %}">
    {% csrf_token %}
    {{ form.as_p }}

    <button name="submit">register</button>
    <input type="hidden" name="next" value="{% url 'learning_logs:index' %}" />
  </form>

{% endblock content %}

4.3 让用户拥有自己的数据

使用@login_required限制访问

# untitled/learning_logs/views.py
from django.contrib.auth.decorators import login_required
from django.http import HttpResponseRedirect
from django.shortcuts import render

# ···

@login_required
def topics(request):
    topics = Topic.objects.order_by('date_added')
    context = {'topics' : topics}
    return render(request, 'learning_logs/topics.html', context)

# ···

# untitled/untitled/settings.py

# ···

LOGIN_URL = '/users/login/'

将数据关联到用户
注意这行代码owner = models.ForeignKey('auth.User', on_delete=models.CASCADE)的写法。

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


class Topic(models.Model):
    """A topic the user is learning about."""
    text = models.CharField(max_length=200)
    date_added = models.DateTimeField(auto_now_add=True)
    owner = models.ForeignKey('auth.User', on_delete=models.CASCADE)

    def __str__(self):
        """Return a string representation of the model."""
        return self.text

我们迁移数据库时，Django将对数据库进行修改，使其能够存储主题和用户之间的关联。
执行python manage.py makemigrations learning_logs时，我们为外键值指定默认值。

只允许用户访问自己的主题

# untitled/learning_logs/views.py

# ···

@login_required
def topics(request):
    topics = Topic.objects.filter(owner=request.user).order_by('date_added')
    context = {'topics' : topics}
    return render(request, 'learning_logs/topics.html', context)

# ···

保护用户的主题

# untitled/learning_logs/views.py

# ···

@login_required
def topic(request, topic_id):
    topic = Topic.objects.get(id=topic_id)
    if topic.owner != request.user:
        raise Http404
    entries = topic.entry_set.order_by('-date_added')
    context = {'topic': topic, 'entries': entries}
    return render(request, 'learning_logs/topic.html', context)

# ···

保护页面edit_entry

# untitled/learning_logs/views.py

# ···

@login_required
def edit_entry(request, entry_id):
    """Edit an existing entry."""
    entry = Entry.objects.get(id=entry_id)
    topic = entry.topic
    if topic.owner != request.user:
        raise Http404

    if request.method != 'POST':
        # Initial request; pre-fill form with the current entry.
        form = EntryForm(instance=entry)
    else:
        # POST data submitted; process data.
        form = EntryForm(instance=entry, data=request.POST)
        if form.is_valid():
            form.save()
            return HttpResponseRedirect(reverse('learning_logs:topic',
                                                args=[topic.id]))

    context = {'entry': entry, 'topic': topic, 'form': form}
    return render(request, 'learning_logs/edit_entry.html', context)

将新主题关联到当前用户

# untitled/learning_logs/views.py

# ···

@login_required
def new_topic(request):
    """添加新主题"""
    if request.method != 'POST':
        form = TopicForm()
    else:
        form = TopicForm(request.POST)
        if form.is_valid():
            new_topic = form.save(commit=False)
            new_topic.owner = request.user
            new_topic.save()
            return HttpResponseRedirect(reverse('learning_logs:topics'))

    context = {'form':form}
    return render(request, 'learning_logs/new_topic.html', context)

# ···

参考资料：《Python编程从入门到实践》—【美】Eric Matthes 著