基于Django的Python应用—学习笔记

一、让用户可以输入信息

创建forms.py

创建基于表单的页面的方法几乎与前面创建网页一样：定义一个 URL ，编写一个视图函数并编写一个模板。一个主要差别是，需要导入包含表单的模块forms.py 。

from django import forms
from .models import Topic,Entry
class TopicForm(forms.ModelForm):class Meta:model = Topicfields = ['text']labels = {'text': ''}class EntryForm(forms.ModelForm):class Meta:model = Entryfields = ['text']labels = {'text': ''}widgets = {'text': forms.Textarea(attrs={'cols': 80})}

将其添加到

learning_logs/urls.py中：

"""定义learning_logs的URL模式"""
from django.urls import path
#从当前的urls.py模块所在的文件夹中导入视图
from . import views
#变量urlpatterns是一个列表，包含可在应用程序learning_logs中请求的网页
app_name = 'learning_logs'
urlpatterns = [#主页#第一个是正则表达式，r让Python将接下来的字符串视为原始字符串，引号正则表达式始于和终于何处#第二个实参指定了要调用的视图函数#第三个实参将这个URL模式的名称指定为indexpath(r'',views.index,name='index'),# 显示所有的主题path(r'topics/', views.topics, name='topics'),# 特定主题的详细页面path(r'^topics/(?P<topic_id>\d+)/$', views.topic, name='topic'),# 用于添加新主题的网页path(r'^new_topic/$', views.new_topic, name='new_topic'),# 用于添加新条目的页面path(r'^new_entry/(?P<topic_id>\d+)/$', views.new_entry, name='new_entry'),# 用于编辑条目的页面path(r'^edit_entry/(?P<entry_id>\d+)/$', views.edit_entry,name='edit_entry'),]

增加视图函数

learning_logs/views.py

from django.shortcuts import render
from django.http import HttpResponseRedirect
from django.urls import reverse
from .models import Topic, Entry
from .forms import TopicForm, EntryForm
# Create your views here.
def index(request):"""学习笔记的主页"""return render(request, 'learning_logs/index.html')
def topics(request):"""显示所有的主题"""topics = Topic.objects.order_by('date_added')context = {'topics': topics}return render(request, 'learning_logs/topics.html', context)
def topic(request, topic_id):"""显示单个主题及其所有的条目"""topic = Topic.objects.get(id=topic_id)entries = topic.entry_set.order_by('-date_added')context = {'topic': topic, 'entries': entries}return render(request, 'learning_logs/topic.html', context)
def new_topic(request):"""添加新主题"""if request.method != 'POST':# 未提交数据：创建一个新表单form = TopicForm()else:# POST提交的数据,对数据进行处理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)
def new_entry(request, topic_id):"""在特定的主题中添加新条目"""topic = Topic.objects.get(id=topic_id)if request.method != 'POST':# 未提交数据,创建一个空表单form = EntryForm()else:# POST提交的数据,对数据进行处理form = EntryForm(data=request.POST)if form.is_valid():new_entry = form.save(commit=False)new_entry.topic = topicnew_entry.save()return HttpResponseRedirect(reverse('learning_logs:topic',args=[topic_id]))context = {'topic': topic, 'form': form}return render(request, 'learning_logs/new_entry.html', context)
def edit_entry(request, entry_id):"""编辑既有条目"""entry = Entry.objects.get(id=entry_id)topic = entry.topicif request.method != 'POST':#   初次请求，使用当前条目填充表单form = EntryForm(instance=entry)else:# POST提交的数据，对数据进行处理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)

二、创建模板

新增三个模板

edit_entry.html

<!DOCTYPE html>
<html lang="en">
<head><meta charset="UTF-8"><title>Title</title>
</head>
<body>
{% extends "learning_logs/base.html" %}
{% block content %}
<p><a href="{% url 'learning_logs:topic' topic.id %}">{{ topic }}</a></p>
<p>Edit entry:</p><form action="{% url 'learning_logs:edit_entry' entry.id %}" method='post'>
{% csrf_token %}
{{ form.as_p }}<button name="submit">save changes</button>
</form>
{% endblock content %}
</body>
</html>

new_entry.html

<!DOCTYPE html>
<html lang="en">
<head><meta charset="UTF-8"><title>Title</title>
</head>
<body>
{% extends "learning_logs/base.html" %}
{% block content %}
<p><a href="{% url 'learning_logs:topic' topic.id %}">{{ topic }}</a></p>
<p>Add a new entry:</p>
<form action="{% url 'learning_logs:new_entry' topic.id %}" method='post'>
{% csrf_token %}
{{ form.as_p }}
<button name='submit'>add entry</button>
</form>
{% endblock content %}
</body>
</html>

new_topic.html

<!DOCTYPE html>
<html lang="en">
<head><meta charset="UTF-8"><title>Title</title>
</head>
<body>
{% 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 %}
</body>
</html>

在页面topics 中添加它们的链接：

<!DOCTYPE html>
<html lang="en">
<head><meta charset="UTF-8"><title>Topics</title>
</head>
<body>
{% extends "learning_logs/base.html" %}
{% block content %}<p>Topics</p>
<ul>{% for topic in topics %}<li><a href="{% url 'learning_logs:topic' topic.id %}">{{ topic }}</a></li>{% empty %}
<li>No topics have been added yet.</li>{% endfor %}
</ul>
<a href="{% url 'learning_logs:new_topic' %}">Add a new topic:</a>{% endblock content %}
</body>
</html>

在页面topic中添加它们的链接：

<!DOCTYPE html>
<html lang="en">
<head><meta charset="UTF-8"><title>Title</title>
</head>
<body>
{% extends "learning_logs/base.html" %}
{% block content %}
<p>Topic: {{ topic }}</p>
<p>Entries:</p>
<p>
<a href="{% url 'learning_logs:new_entry' topic.id %}">add new entry</a>
</p><ul>{% for entry in entries %}
<li><p>{{ entry.date_added|date:'M d, Y H:i' }}</p><p>{{ entry.text|linebreaks }}</p><p>
<a href="{% url 'learning_logs:edit_entry' entry.id %}">edit entry</a>
</p>
</li>{% empty %}
<li>
There are no entries for this topic yet.
</li>
{% endfor %}{% endblock content %}
</ul>
</body>
</html>