django基础之简单使用

当前python版本3.10.8  django版本4.1.3  

准备开始

# 安装
pip install django

# 查看django版本
py -m django --version

# 新建项目
mkdir demo
django-admin startproject mysite demo

#生成mysite目录结构
# demo/mysite目录
#    __init__.py
#    asgi.py
#    settings.py
#    urls.py
#    wsgi.py
# manage.py

# 启动
py manage.py runserver 8000 #打开浏览器访问127.0.0.1:8000

manage.py: 管理 Django 项目的命令行工具。

mysite/__init__.py：一个空文件，告诉 Python 这个目录应该被认为是一个 Python 包。

mysite/settings.py：Django 项目的配置文件。

mysite/urls.py：Django 项目的 URL 声明，就像网站的“目录”。

mysite/asgi.py：项目运行在 ASGI 兼容的 Web 服务器上的入口。

mysite/wsgi.py：项目运行在 WSGI 兼容的Web服务器上的入口。

新增url 

# mysite目录下新建views.py
from django.shortcuts import render,HttpResponse 

def hello(req):    
    return HttpResponse("hello world!")

# mysite/urls.py
from django.contrib import admin
from django.urls import path
from . import views

urlpatterns = [
    path('hello/', views.hello),
]

 增加应用

py manage.py startapp post
# 生成 mysite/post目录和目录下 admin.py  apps.py  models.py tests.py views.py __init__.py

# mysite/setting.py中INSTALLED_APPS增加 post
INSTALLED_APPS = [
     ...
    'post'
]

# post/views.py 
from django.shortcuts import render,HttpResponse 
def index(request):
    return HttpResponse('post/index')


# 创建post/urls.py
from django.urls import path
from . import views
urlpatterns = [
    path('index', views.index,name="index"),
]

# mysite/urls.py
urlpatterns = [
    ...
    path('post/', include('post.urls')),
]

 创建模型

 Django将关系型的表(table)转换成为一个类(class)。而每个记录(record)是该类下的一个对象(object)。我们可以使用基于对象的方法，来操纵关系型的数据库。

# post/models.py
from django.db import models
class Post(models.Model):
    """post"""
    title=models.CharField(max_length=50)
    content=models.CharField(max_length=500)
    create_at=models.DateTimeField(auto_now_add=True)

    def __str__(self):
        """返回模型的字符串表示"""
        return self.title

# 根据模型生成迁移
py manage.py makemigrations

# 将迁移更新到DB
py manage.py migrate post 

# post/views.py添加
from  post.models import Post
def lists(request):
    post_list = Post.objects.all()
    post_str  = map(str, post_list)
    return HttpResponse("<p>" + ' '.join(post_str) + "</p>")

def create(request):
    post=Post(title='bb',content='bbbbbbb')
    post.save()
    return HttpResponse("<p>created bb </p>")

# post/urls.py添加
urlpatterns = [
    ...
    path('lists',views.lists,name="lists"),
    path('create',views.create,name="create"),
]

引入模板 

# mysite/setting.py增加配置 
TEMPLATES =[
    {
        'BACKEND': 'django.template.backends.django.DjangoTemplates',
        'DIRS': [os.path.join(BASE_DIR,'templates')],
        'APP_DIRS': True, #允许每个app使用自己的templates目录
        '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',
            ],
        },
    }, 
]

# post/views.py 中lists修改为
def lists(request):
    post_list = Post.objects.all()
    post_str  = map(str, post_list)
    return render(request,'post/lists.html',{'str':' '.join(post_str),'num':len(post_list) })

# demo目录下创建templates目录，templates下创建post目录/lists.html
<p>I am out post lists {{str}}</p>
<p>nums :{{num}}</p>

# post目录下创建templates/post/lists.html  
# Django按照INSTALLED_APPS中的添加顺序查找Templates，不同的app下templates目录中的同名XX.html会造成冲突
<p>I am inner post lists {{str}}</p>
<p>nums :{{num}}</p>

# 访问http://127.0.0.1:8000/post/lists
I am out post lists aa bb
nums :2

# 删除demo/templates/post/lists.html文件，访问http://127.0.0.1:8000/post/lists
I am inner post lists aa bb
nums :2

加入模板语法 

# post/views.py 中lists修改为
def lists(request):
    post_list = Post.objects.all()
    return render(request,'post/lists.html',{'lists':post_list})

# 创建demo/templates/post/lists.html文件
{% if lists %} {% for item in lists %} {% if forloop.first %}
<div style="color: red">
  <p>id: {{item.id}}</p>
  <p>title:{{item.title}}</p>
  <p>content:{{item.content}}</p>
  <p>created_at:{{item.created_at}}</p>
</div>
{% elif forloop.last %}
<div style="color: blue">
  <p>id: {{item.id}}</p>
  <p>title:{{item.title}}</p>
  <p>content:{{item.content}}</p>
  <p>created_at:{{item.created_at}}</p>
</div>
{% else %}
<div style="color: green">
  <p>id: {{item.id}}</p>
  <p>title:{{item.title}}</p>
  <p>content:{{item.content}}</p>
  <p>created_at:{{item.created_at}}</p>
</div>
{% endif %} {% endfor %}
<p>nums :{{lists|length}}</p>
<p>{{ value|default:'nothing' }}</p>
{% else %} No data {% endif %}

静态文件

# demo/mysite/settings.py 配置静态文件存放位置
STATIC_URL = 'static/'
STATICFILES_DIRS = (
  os.path.join(BASE_DIR, 'static'),
)

# 创建demo/static目录，放入plugins/bootstrap-5.1.3-dist 包，创建demo/templates/layout.html文件
{% load static %}
<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <link rel="stylesheet" href="{% static 'plugins/bootstrap-5.1.3-dist/css/bootstrap.min.css' %}" />
    <script type="text/javascript" src="{% static 'plugins/bootstrap-5.1.3-dist/js/bootstrap.bundle.min.js' %}"></script>
    <title>Document</title>
  </head>
  <body>
    <nav class="navbar navbar-expand-lg navbar-light bg-light">
      <div class="container-fluid">
        <a class="navbar-brand" href="#">Navbar</a>
        <div class="collapse navbar-collapse">
          <ul class="navbar-nav me-auto mb-2 mb-lg-0">
            <li class="nav-item">
              <a class="nav-link active" aria-current="page" href="#">Home</a>
            </li>
            <li class="nav-item">
              <a class="nav-link" href="#">Link</a>
            </li>
          </ul>
        </div>
      </div>
    </nav>
    <div class="container-fluid mt-3">
      {% block mainbody %}
      <p>welecome</p>
      {% endblock %}
    </div>
  </body>
</html>

# 修改demo/templates/post/lists.html,模板继承自layout.html
{% extends "layout.html" %} {% block mainbody %} {% if lists %}
<div class="row">
  {% for item in lists %}
  <div class="col-3">
    <div class="card">
      <div class="card-header">{{item.id}}</div>
      <div class="card-body">
        <h5 class="card-title">{{item.title}}</h5>
        <p class="card-text">{{item.content}}</p>
      </div>
    </div>
  </div>
  {% endfor %}
</div>
{% else %}
<div class="alert alert-danger" role="alert">No data</div>
{% endif %} {% endblock %}

 

form和保存数据

# 创建demo/templates/post/create.html
{% extends "layout.html" %} {% block mainbody %}
<div class="row">
  <div class="col-6">
    <div class="card">
      <div class="card-header">create</div>
      <form action="/post/create" method="post">
        {% csrf_token %}
        <div class="card-body">
          <div class="input-group mb-3">
            <span class="input-group-text">title</span>
            <input type="text" class="form-control" name="title" />
          </div>
          <div class="input-group mb-3">
            <span class="input-group-text">content</span>
            <textarea class="form-control" name="content"></textarea>
          </div>
        </div>
        <div class="card-footer">
          <button type="submit" class="btn btn-primary">Submit</button>
        </div>
      </form>
    </div>
  </div>
  {% if p %}
  <div class="col-6">
    <div class="card">
      <div class="card-header">{{p.id}}</div>
      <div class="card-body">
        <h5 class="card-title">{{p.title}}</h5>
        <p class="card-text">{{p.content}}</p>
      </div>
    </div>
  </div>
  {% endif %}
</div>
{% endblock %}

# demo/post/views.py增加
def create(request):
    if request.POST:
        title = request.POST['title']
        content=request.POST['content']
        p=Post(title=title,content=content)
        p.save()
        return render(request,'post/create.html',{'p':p})

    return render(request,'post/create.html')

加入表单数据验证

# demo/post/views.py
def create(request):
    if request.POST:
        form = PostForm(request.POST)
        if form.is_valid():
            title = form.cleaned_data['title']
            content=form.cleaned_data['content']
            p=Post(title=title,content=content)
            p.save()
            return render(request,'post/create.html',{'p':p})
        else:
            return render(request,'post/create.html',{'errors':form.errors})
    return render(request,'post/create.html')

# demo/templates/post/create.html
{% extends "layout.html" %} {% block mainbody %}
<div class="row">
  <div class="col-6">
    <div class="card">
      <div class="card-header">create</div>
      <form action="/post/create" method="post">
        {% csrf_token %}
        <div class="card-body">
          <div class="input-group mb-3">
            <span class="input-group-text">title</span>
            <input type="text" class="form-control" name="title" />
          </div>
          <div class="input-group mb-3">
            <span class="input-group-text">content</span>
            <textarea class="form-control" name="content"></textarea>
          </div>
          {% if errors %}
          <div class="alert alert-warning" role="alert">{% for item in errors.values %} {{item}} {% endfor %}</div>
          {% endif %}
        </div>
        <div class="card-footer">
          <button type="submit" class="btn btn-primary">Submit</button>
        </div>
      </form>
    </div>
  </div>
  {% if p %}
  <div class="col-6">
    <div class="card">
      <div class="card-header">{{p.id}}</div>
      <div class="card-body">
        <h5 class="card-title">{{p.title}}</h5>
        <p class="card-text">{{p.content}}</p>
      </div>
    </div>
  </div>
  {% endif %}
</div>
{% endblock %}

使用django admin强大的管理功能 

# demo/post/models.py增加
class Contact(models.Model):
    name   = models.CharField(max_length=200)
    age    = models.IntegerField(default=0)
    email  = models.EmailField()
    def __str__(self):
        return self.name
class Tag(models.Model):
    contact = models.ForeignKey(Contact, on_delete=models.CASCADE)
    name    = models.CharField(max_length=50)
    def __str__(self):
        return self.name

# 迁移
py manage.py makemigrations
py manage.py migrate

# 创建superuser
py manage.py createsuperuser

# demo/post/admin.py增加
from post.models import Post,Contact,Tag

class TagInline(admin.TabularInline):
    model = Tag
    
class ContactAdmin(admin.ModelAdmin):
    list_display = ('name','age', 'email') 
    inlines = [TagInline]  
    search_fields = ('name','email')
    #fields = ('name', 'email')
    fieldsets = (
        ['Main',{
            'fields':('name','email'),
        }],
        ['Advance',{
            'classes': ('collapse',), # CSS
            'fields': ('age',),
        }]
    )
admin.site.register(Contact, ContactAdmin)
admin.site.register([Post,Tag])