一、创建一个Django项目
1、使用虚拟环境
#快速创建虚拟环境 python -m venv prjvenv #激活虚拟环境 source prjvenv/bin/activate
2、创建项目
#安装django pip install django #创建项目 django-admin startproject myblog
3、django设置
myblog/settings.py文件
TIME_ZONE='Asia/Shanghai'
4、数据库迁移
python manage.py migrate
5、启动
python manage.py runserver
二、视图和URL配置
myblog/views.py文件
from django.http import HttpResponse
#最简单视图
def hello(request):
return HttpResponse("Hello world")
#带参数的视图
def hours_ahead(request, offset):
try:
offset = int(offset)
except ValueError:
raise Http404()
dt = datetime.datetime.now() + datetime.timedelta(hours=offset)
html = "In %s hour(s), it will be %s." % (offset, dt)
return HttpResponse(html)
myblog/urls.py 文件
from django.conf.urls import url
from django.contrib import admin
from myblog.views import hello
from mysite.views import hours_ahead
urlpatterns = [
url(r'^admin/', admin.site.urls),
url(r'^hello/$',hello),
url(r'^time/plus/(\d{1,2})/$', hours_ahead),
]
三、使用Django模板
1、模板目录配置
myblog/settings.py文件
TEMPLATES = [
{
'BACKEND': 'django.template.backends.django.DjangoTemplates',
'DIRS': ['app1/templates','app2/templates'...],
'APP_DIRS': True,
'OPTIONS': {
'context_processors': [
'django.template.context_processors.debug',
'django.template.context_processors.request',
'django.contrib.auth.context_processors.auth',
'django.contrib.messages.context_processors.messages',
],
},
},
]
如果想在项目根目录中放一些主模板(例如在 mysite/templates 目录中)，需要像这样设定 DIRS:
'DIRS': [os.path.join(BASE_DIR, 'templates')],
2、视图函数
from django.shortcuts import render
import datetime
def current_datetime(request):
now = datetime.datetime.now()
return render(request, 'current_datetime.html', {'current_date': now})
3、模板文件
myblog/templates/base.html文件
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN">
<html>
<head>
<title>{% block title %}{% endblock %}</title>
</head>
<body>
<h1>My helpful timestamp site</h1>
{% block content %}{% endblock %}
{% block footer %}<hr>
<p>Thanks for visiting my site.</p>
{% endblock %}
</body>
</html>
四、模型
1、配置数据库
myblog/setting.py
DATABASES = {
'default': {
'ENGINE': 'django.db.backends.sqlite3',
'NAME': os.path.join(BASE_DIR, 'db.sqlite3'),
} }
2、创建应用
python manage.py startapp books
3、激活应用
INSTALLED_APPS = ( ... 'books', )
4、创建模型
myblogs/books/models.py
from django.db import models class Publisher(models.Model): name = models.CharField(max_length=30) address = models.CharField(max_length=50) city = models.CharField(max_length=60) state_province = models.CharField(max_length=30) country = models.CharField(max_length=50) website = models.URLField() def __str__(self): return self.name class Author(models.Model): first_name = models.CharField(max_length=30) last_name = models.CharField(max_length=40) email = models.EmailField() def __str__(self): return self.last_name class Book(models.Model): title = models.CharField(max_length=100) authors = models.ManyToManyField(Author) publisher = models.ForeignKey(Publisher,on_delete=models.CASCADE) publication_date = models.DateField() def __str__(self): return self.title
5、迁移数据库
#括号中的内容可以不需要 python manage.py makemigrations (books) python manage.py migrate
6、操作数据
新增数据
方式一： p1 = Publisher(...) p1.save() 方式二： p1 = Publisher.objects.create(...)
更新数据
方式一： p.name = 'Apress Publishing' p.save() 方式二： Publisher.objects.filter(id=52).update(name='Apress') #推荐
查询数据
返回查询集合
Publisher.objects.all() Publisher.objects.filter(name='Apress') #WHERE name = 'Apress'; Publisher.objects.filter(name__contains="press") #WHERE name LIKE '%press%';
返回单个对象
Publisher.objects.get(name="Apress") #不是1个对象就会报异常
try:
p = Publisher.objects.get(name='Apress') #数据库中存在一个数据
except Publisher.DoesNotExist:
print ("Apress isn't in the database yet.") #数据库中没有数据
else:
print ("Apress is in the database.") #有多个数据
删除
方式一：单个删除 p = Publisher.objects.get(name="O'Reilly") p.delete() 方式二：批量删除 Publisher.objects.filter(country='USA').delete() Publisher.objects.all().delete()
排序
方式一：使用order_by()
Publisher.objects.order_by("name", "age") #根据姓名和年龄排序，-name/-age实现反向排序
方式二：在模型内定义
class Publisher(models.Model):
...
class Meta:
ordering = ['name']
切片
Publisher.objects.order_by('name')[0:2]
五、后台管理
1、创建管理员用户
python manage.py createsuperuser
2、将模型添加到后台管理
myblog/books/admin.py文件
from django.contrib import admin from .models import Publisher, Author, Book admin.site.register(Publisher) admin.site.register(Author) admin.site.register(Book)
3、修改模型，使字段在后台输入时变为可选项
myblog/books/models.py
class Book(models.Model): title = models.CharField(max_length=100) authors = models.ManyToManyField(Author) publisher = models.ForeignKey(Publisher,on_delete=models.CASCADE) publication_date = models.DateField(blank=True, null=True)
注意：如果想让日期字段(如 DateField、TimeField、DateTimeField)或数值字段(如 IntegerField、DecimalField、FloatField)接受空值，要同时添加 null=True 和 blank=True。
4、通过模型字段的verbose_name值指定后台显示的字段别名
myblog/books/models.py
class Author(models.Model): first_name = models.CharField(max_length=30) last_name = models.CharField(max_length=40) email = models.EmailField(blank=True, verbose_name='e-mail')
5、自定义修改后台管理列表
myblog/books/admin.py文件
from django.contrib import admin
from .models import Publisher, Author, Book
#自定义Author的后台管理列表
class AuthorAdmin(admin.ModelAdmin):
list_display = ('first_name', 'last_name', 'email') #定义显示字段
search_fields = ('first_name', 'last_name') #添加字段搜索
#自定义Book的后台管理列表
class BookAdmin(admin.ModelAdmin):
list_display = ('title', 'publisher', 'publication_date') #定义显示字段
list_filter = ('publication_date',) #添加时间过滤器
date_hierarchy = 'publication_date' #另一种日期过滤器
ordering = ('-publication_date',) #排序
fields = ('title', 'authors', 'publisher', 'publication_date') #自定义修改表单
filter_horizontal = ('authors',) #使用选项框(多对多关系时使用)
raw_id_fields = ('publisher',) #通过id选择对应选项
admin.site.register(Publisher)
admin.site.register(Author,AuthorAdmin)
admin.site.register(Book,BookAdmin)
六、表单
（1）原生表单
1、获取request数据应该try或者设置默认值，防止报错
方式一：
def ua_display_good1(request):
try:
ua = request.META['HTTP_USER_AGENT']
except KeyError:
ua = 'unknown'
return HttpResponse("Your browser is %s" % ua)
方式二：
def ua_display_good2(request):
ua = request.META.get('HTTP_USER_AGENT', 'unknown')
return HttpResponse("Your browser is %s" % ua)
2、简单的表单提交及表单实例
get和post指向相同的url，根据 if ‘q’ in request.GET:判断是GET还是POST
模板页面
#表单页面：myblog/templates/search_form.html <html> <head> <title>Search</title> </head> <body> {% if errors %} #提示错误信息 <ul> {% for error in errors %} <li>{{ error }}</li> {% endfor %} </ul> {% endif %} <form action="" method="get"> #action为空，表示提交到当前页面 <input type="text" name="q"> <input type="submit" value="Search"> </form> </body> </html>#结果展示页面：myblog/templates/search_results.html <html> <head> <title>Book Search</title> </head> <body> <p>You searched for: <strong>{{ query }}</strong></p> {% if books %} <p>Found {{ books|length }} book{{ books|pluralize }}.</p> <ul> {% for book in books %} <li>{{ book.title }}</li> {% endfor %} </ul> {% else %} <p>No books matched your search criteria.</p> {% endif %} </body> </html>
视图函数：myblog/books/views.py文件
from django.shortcuts import render
from django.http import HttpResponse
def search(request):
errors = []
if 'q' in request.GET: # 如果是post,则存在GET['q']
q = request.GET['q']
if not q:
errors.append('Enter a search term.') # 提交了表单，但是内容为空
elif len(q) > 20: # 提交表单，长度超过限制
errors.append('Please enter at most 20 characters.')
else: # 正常提交数据
books = Book.objects.filter(title__icontains=q)
return render(request, 'search_results.html',
{'books': books, 'query': q})
return render(request, 'search_form.html',{'errors': errors}) #不存在GET['q']说明是GET请求
路由：myblog/urls.py文件
urlpatterns = [ ... url(r'^search/$',views.search) ]
（2）Django表单模型
1、定义表单类
myblog/books/forms.py
from django import forms
class ContactForm(forms.Form):
subject = forms.CharField(max_length=100) # max_length指定最大长度
email = forms.EmailField(required=False)
message = forms.CharField(widget=forms.Textarea) # widget参数，指定表现逻辑，此次指定为文本框
def clean_message(self): # 自定义验表单证器
message = self.cleaned_data['message']
num_words = len(message.split())
if num_words < 4:
raise forms.ValidationError("Not enough words!")
return message
自定义表单验证器：Django 的表单系统会自动查找名称以 clean_ 开头、以字段名结尾的方法。如果存在这样的方法，在验证过 程中调用。这里，clean_message() 方法会在指定字段的默认验证逻辑(这个 CharField 是必填的)执行完毕后调用。
2、视图函数
myblog/books/views.py
from books.forms import ContactForm
def contact(request):
if request.method == 'POST':
form = ContactForm(request.POST)
if form.is_valid():
cd = form.cleaned_data
#提示：如果没有配置邮件服务器，调用 send_mail() 时会抛出 ConnectionRefusedError。
send_mail(
cd['subject'],
cd['message'],
cd.get('email', 'noreply@example.com'),
['siteowner@example.com'],
)
return HttpResponseRedirect('/contact/thanks/')
else:
form = ContactForm(
initial={'subject': 'I love your site!'} # 可以初始值
)
return render(request, 'contact_form.html', {'form': form})
3、表单页面
myblogs/templates/contact_form.html
方式一：使用系统默认表单
<html> <head> <title>Contact us</title> </head> <body> <h1>Contact us</h1> {% if form.errors %} <p style="color: red;"> Please correct the error{{ form.errors|pluralize }} below. </p> {% endif %} <form action="" method="post"> {% csrf_token %} <table> {{ form.as_table }} </table> {% csrf_token %} <input type="submit" value="Submit"> </form> </body> </html>方式二：自定义表单外观样式
<html> <head> <title>Contact us</title> </head> <body> <h1>Contact us</h1> {% if form.errors %} <p style="color: red;"> Please correct the error{{ form.errors|pluralize }} below. </p> {% endif %} <form action="" method="post"> <div> {{ form.subject.errors }} <label for="id_subject">Subject:</label> {{ form.subject }} </div> <div> {{ form.email.errors }} <label for="id_email">e-mail:</label> {{ form.email }} </div> <div> {{ form.message.errors }} <label for="id_message">Message:</label> {{ form.message }} </div> {% csrf_token %} <input type="submit" value="Submit"> </form> </body> </html>
4、路由设置
myblogs/myblogs/urls.py
urlpatterns = [ ... url(r'^contact/$', views.contact), ]
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