Django框架进阶5 models常用字段及参数, choices参数, 自动显示sql命令配置, orm查询优化相关, orm中的事务操作, MTV与MVC模型, 图书管理系统(图书的增删改查)

models中的常用字段

AutoField(primary_key=True)　　主键   (int自增列，必须填入参数 primary_key=True。当model中如果没有自增列，则自动会创建一个列名为id的列。)

CharField(max_length=32)     varchar(32)

IntegerField()       int

BigIntergerField()           bigint

DecimalField()   　　decimal

EmailField()     　　varchar(254)

DateField() 　　　　date

DateTimeField()　　datetime

　　auto_now:每次编辑数据的时候都会自动更新该字段时间

　　auto_now_add:创建数据的时候自动更新

BooleanField(Field)

　　给该字段传布尔值  会对影成   数字0/1

　　is_delete

　　is_status

　　is_vip

TextField(Field)

　　-文本类型　　存储大段文本

FileField(Field)

　　- 字符串，路径保存在数据库，文件上传到指定目录，只存文件路径

　　　　upload_to = '指定文件路径'

　　　　给该字段传文件对象 文件会自动保存到upload_to指定的文件夹下 然后该字段存文件的路径

 

如何自定义char类型字段

from django.db.models import Field

class RealCharField(Field):
    def __init__(self,max_length,*args,**kwargs):
        self.max_length = max_length  # 拦截一个父类的方法 操作完之后 利用super调用父类的方法
        super().__init__(max_length=max_length,*args,**kwargs)

    def db_type(self, connection):
        return 'char(%s)'%self.max_length
        
class Movie(models.Model):
    textField = RealCharField(max_length=64)

 

字段内的关键性参数

　　null　　null=True　　允许字段为空，必须用null

　　default　　默认参数

　　django  1.x默认就是级联更新级联删除  django2.x需要你自己手动指定

　　　　on_delete = models.CASCADE

　　　　db_contraints = True

　　　　# 百度

 

choice参数

　　用户的性别
　　学历
　　婚否
　　在职状态
　　客户来源
　　当你的数据能够被你列举完全 你就可以考虑使用choices参数

models.py

class Userinfo(models.Model):
    username = models.CharField(max_length=32)
    gender_choices = (
        (1,'男'),
        (2,'女'),
        (3,'其他'),
    )
    gender = models.IntegerField(choices=gender_choices)
    # 该字段还是存数字 并且可以匹配关系之外的数字
    record_choices = (('checked','已签到'),
                      ('vacate','请假'),
                      ('noshow','缺勤'),
                      ('leave_early','早退'),
                      )
    record = models.CharField('上课记录',choices=record_choices,default='checked',max_length=64)

test.py

user_obj = models.Userinfo.objects.get(pk=1)
print(user_obj.username)
print(user_obj.gender)
# 针对choices参数字段 取值的时候   get_xxx_display()
print(user_obj.get_gender_display())
# 针对没有注释信息的数据  get_xxx_display()获取到的还是数字本身
user_obj = models.Userinfo.objects.get(pk=4)
print(user_obj.gender)        # 100
print(user_obj.get_gender_display())    # 100

 

django自动显示sql命令配置

settings.py文件中加入

LOGGING = {
    'version': 1,
    'disable_existing_loggers': False,
    'handlers': {
        'console':{
            'level':'DEBUG',
            'class':'logging.StreamHandler',
        },
    },
    'loggers': {
        'django.db.backends': {
            'handlers': ['console'],
            'propagate': True,
            'level':'DEBUG',
        },
    }
}

 

数据库查询优化(面试会问)

only与defer

only作用
    括号内传字段 得到的结果是一个列表套数据对象 该对象内只含有括号内指定的字段属性
    对象点该字段属性是不会走数据库的 但是你一旦点了非括号内的字段 也能够拿到数据
    但是是重新走的数据库查询吧

defer与only相反
    括号内传字段 得到的结果是一个列表套数据对象 该对象内没有括号内指定的字段属性
    对象点该字段属性会重复走数据库 但是你一旦点了非括号内的字段 就不走数据库了

 # res = models.Book.objects.all()  # django orm查询都是惰性查询
    # print(res)


    # res = models.Book.objects.values('title')
    # print(res)
    # for r in res:
    #     print(r.title)

    # res = models.Book.objects.only('title')  # 這些對象内部只有title屬性
    # # print(res)
    # for r in res:
    #     # print(r.title)
    #     print(r.price)    # 内部会重新遍历，寻找价格
    """
    only作用
        括号内传字段 得到的结果是一个列表套数据对象 该对象内只含有括号内指定的字段属性
        对象点该字段属性是不会走数据库的 但是你一旦点了非括号内的字段 也能够拿到数据
        但是是重新走的数据库查询吧
    """

    # res = models.Book.objects.defer('title')  # defer与only互为反关系
    # for r in res:
    #     print(r.title)
    """
    defer与only相反
        括号内传字段 得到的结果是一个列表套数据对象 该对象内没有括号内指定的字段属性
        对象点该字段属性会重复走数据库 但是你一旦点了非括号内的字段 就不走数据库了
    """

selected_related与prefetch_related

selected_related

内部是连表操作 现将关系表全部链接起来 之后再一次性查询出来 封装到对象中
数据对象之后在获取任意表中的数据的时候都不需要再走数据库了 因为全部封装成了对象的属性

select_related括号内只能传外键字段 并且不能是多对多字段 只能是一对多和一对一
select_related(外键字段1__外键字段2__外键字段3...)

prefetch_related

prefetch_related内部是子查询 但是给你的感觉是连表操作
内部通过子查询将外键管理表中的数据页全部给你封装到对象中
之后对象点当前表或者外键关联表中的字段也都不需要走数据库了

优缺点比较

select_related连表操作 好处在于只走一次sql查询
    耗时耗在 连接表的操作  10s
    
prefetch_related子查询  走两次sql查询
    耗时耗在 查询次数      1s

 # select_related和prefetch_related
    # res = models.Book.objects.get(pk=1)
    # print(res.publish.name)

    # res = models.Book.objects.select_related('publish')
    # for r in res:
    #     print(r.publish.name)
    #     print(r.publish.addr)
    """
    内部是连表操作 现将关系表全部链接起来 之后再一次性查询出来 封装到对象中
    数据对象之后在获取任意表中的数据的时候都不需要再走数据库了 因为全部封装成了对象的属性
    
    select_related括号内只能传外键字段 并且不能是多对多字段 只能是一对多和一对一
    select_related(外键字段1__外键字段2__外键字段3...)
    """

    # prefetch_related
    # res = models.Book.objects.prefetch_related('publish')
    # # print(res)
    #
    # for r in res:
    #     print(r.publish.name)

    """
    prefetch_related内部是子查询 但是给你的感觉是连表操作
    内部通过子查询将外键管理表中的数据页全部给你封装到对象中
    之后对象点当前表或者外键关联表中的字段也都不需要走数据库了
    """
    """
    优缺点比较
    select_related连表操作 好处在于只走一次sql查询
        耗时耗在 连接表的操作  10s
        
    prefetch_related子查询  走两次sql查询
        耗时耗在 查询次数      1s
    """

 

django orm如何开启事务操作

事务的四大特性(ACID)

　　原子性

　　一致性

　　隔离性

　　持久性

start transaction
rollback
commit

代码：

# django orm开启事务操作
from django.db import transaction
with transaction.atomic():
    # 在with代码块中执行的orm语句同属于一个事务
    pass

# 代码块运行结束 事务就结束了  事务相关的其他配置 你可以百度搜搜看

 

MTV与MVC模型

MTV 　　django号称是MTV框架

　　M:models

　　T:templates

　　V:views

MVC

　　M:models

　　V:views

　　C:controller　　控制器(路由分发  urls.py)

本质:MTV本质也是MVC

 

BMS　　图书管理系统

 代码：

 app01/models.py

from django.db import models

# Create your models here.
from django.db.models import Field

class RealCharField(Field):
    def __init__(self,max_length,*args,**kwargs):
        self.max_length = max_length    # 拦截一个父类的方法 操作完之后 利用super调用父类的方法
        super().__init__(max_length=max_length,*args,**kwargs)

    def db_type(self,connection):
        return 'char(%s)'%self.max_length

class Movie(models.Model):
    textField = RealCharField(max_length=64)


class Userinfo(models.Model):
    username = models.CharField(max_length=32)
    gender_choices = (
        (1,'男'),
        (2,'女'),
        (3,'其他'),
    )
    gender = models.IntegerField(choices=gender_choices)
    # 该字段还是存数字 并且可以匹配关系之外的数字
    record_choices = (('checked','已签到'),
                      ('vacate','请假'),
                      ('noshow','缺勤'),
                      ('leave_early','早退'),
                      )
    record = models.CharField('上课记录',choices=record_choices,default='checked',max_length=64)

class Book(models.Model):
    title = models.CharField(max_length=32)
    price = models.CharField(max_length=32)
    publish_time = models.DateField(auto_now_add=True)

    authors = models.ManyToManyField(to='Author')
    publish = models.ForeignKey(to='Publish')

class Publish(models.Model):
    name = models.CharField(max_length=32)
    addr = models.CharField(max_length=64)

class Author(models.Model):
    name = models.CharField(max_length=32)
    age = models.IntegerField()
    author_detail = models.OneToOneField(to='AuthorDetail')

class AuthorDetail(models.Model):
    phone = models.BigIntegerField()
    addr = models.CharField(max_length=64)

app01/views.py

from django.shortcuts import render,HttpResponse,redirect,reverse
from app01 import models

# Create your views here.
def home(request):
    return render(request,'home.html')

def show_book(request):
    book_queryset = models.Book.objects.all()
    return render(request,'book_list.html',locals())

def add_book(request):
    if request.method == 'POST':
        title = request.POST.get('title')
        price = request.POST.get('price')
        publish_time = request.POST.get('publish_time')
        publish_id = request.POST.get('publish')
        authors_list = request.POST.getlist('authors')

        book_obj = models.Book.objects.create(title=title,price=price,publish_time=publish_time,publish_id=publish_id)
        # 书籍与作者关系
        book_obj.authors.add(*authors_list)
        _url = reverse('show')
        return redirect(_url)

    publish_queryset = models.Publish.objects.all()
    author_queryset = models.Author.objects.all()
    return render(request,'add_book.html',locals())

def edit_book(request,edit_id):
    edit_obj = models.Book.objects.filter(pk=edit_id).first()
    if request.method == 'POST':
        title = request.POST.get('title')
        price = request.POST.get('price')
        publish_time = request.POST.get('publish_time')
        publish_id = request.POST.get('publish')
        author_list = request.POST.getlist('authors')
        models.Book.objects.filter(pk=edit_id).update(title=title,price=price,publish_time=publish_time,publish_id=publish_id)
        edit_obj.authors.set(author_list)
        # 重定向到书籍展示页
        _url = reverse('show')
        return redirect(_url)

    publish_queryset = models.Publish.objects.all()
    author_queryset = models.Author.objects.all()
    return render(request,'edit_book.html',locals())

def delete_book(request,delete_id):
    models.Book.objects.filter(pk=delete_id).delete()

    _url = reverse('show')
    return redirect(_url)

BMS/__init__.py

import pymysql
pymysql.install_as_MySQLdb()

BMS/settings.py

"""
Django settings for BMS project.

Generated by 'django-admin startproject' using Django 1.11.11.

For more information on this file, see
https://docs.djangoproject.com/en/1.11/topics/settings/

For the full list of settings and their values, see
https://docs.djangoproject.com/en/1.11/ref/settings/
"""

import os

# Build paths inside the project like this: os.path.join(BASE_DIR, ...)
BASE_DIR = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))


# Quick-start development settings - unsuitable for production
# See https://docs.djangoproject.com/en/1.11/howto/deployment/checklist/

# SECURITY WARNING: keep the secret key used in production secret!
SECRET_KEY = '9j+w4f3$e%&3su_1d7-dp)hh*&#yz$xwfyp=#q=j5k-5&-yh!y'

# SECURITY WARNING: don't run with debug turned on in production!
DEBUG = True

ALLOWED_HOSTS = []


# Application definition

INSTALLED_APPS = [
    'django.contrib.admin',
    'django.contrib.auth',
    'django.contrib.contenttypes',
    'django.contrib.sessions',
    'django.contrib.messages',
    'django.contrib.staticfiles',
    'app01.apps.App01Config',
]

MIDDLEWARE = [
    'django.middleware.security.SecurityMiddleware',
    'django.contrib.sessions.middleware.SessionMiddleware',
    'django.middleware.common.CommonMiddleware',
    # 'django.middleware.csrf.CsrfViewMiddleware',
    'django.contrib.auth.middleware.AuthenticationMiddleware',
    'django.contrib.messages.middleware.MessageMiddleware',
    'django.middleware.clickjacking.XFrameOptionsMiddleware',
]

ROOT_URLCONF = 'BMS.urls'

TEMPLATES = [
    {
        'BACKEND': 'django.template.backends.django.DjangoTemplates',
        'DIRS': [os.path.join(BASE_DIR, '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',
            ],
        },
    },
]

WSGI_APPLICATION = 'BMS.wsgi.application'


# Database
# https://docs.djangoproject.com/en/1.11/ref/settings/#databases

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.mysql',
        'NAME': 'BMS',
        'USER':'root',
        'PASSWORD':'',
        'HOST':'127.0.0.1',
        'PORT':3306,
        'CHARSET':'utf8',
    }
}


# Password validation
# https://docs.djangoproject.com/en/1.11/ref/settings/#auth-password-validators

AUTH_PASSWORD_VALIDATORS = [
    {
        'NAME': 'django.contrib.auth.password_validation.UserAttributeSimilarityValidator',
    },
    {
        'NAME': 'django.contrib.auth.password_validation.MinimumLengthValidator',
    },
    {
        'NAME': 'django.contrib.auth.password_validation.CommonPasswordValidator',
    },
    {
        'NAME': 'django.contrib.auth.password_validation.NumericPasswordValidator',
    },
]


# Internationalization
# https://docs.djangoproject.com/en/1.11/topics/i18n/

LANGUAGE_CODE = 'en-us'

TIME_ZONE = 'UTC'

USE_I18N = True

USE_L10N = True

USE_TZ = True


# Static files (CSS, JavaScript, Images)
# https://docs.djangoproject.com/en/1.11/howto/static-files/

STATIC_URL = '/static/'
STATICFILES_DIRS = [
    os.path.join(BASE_DIR,'static')
]

# 自动显示命令对应sql命令
# LOGGING = {
#     'version': 1,
#     'disable_existing_loggers': False,
#     'handlers': {
#         'console':{
#             'level':'DEBUG',
#             'class':'logging.StreamHandler',
#         },
#     },
#     'loggers': {
#         'django.db.backends': {
#             'handlers': ['console'],
#             'propagate': True,
#             'level':'DEBUG',
#         },
#     }
# }

BMS/urls.py

"""BMS URL Configuration

The `urlpatterns` list routes URLs to views. For more information please see:
    https://docs.djangoproject.com/en/1.11/topics/http/urls/
Examples:
Function views
    1. Add an import:  from my_app import views
    2. Add a URL to urlpatterns:  url(r'^$', views.home, name='home')
Class-based views
    1. Add an import:  from other_app.views import Home
    2. Add a URL to urlpatterns:  url(r'^$', Home.as_view(), name='home')
Including another URLconf
    1. Import the include() function: from django.conf.urls import url, include
    2. Add a URL to urlpatterns:  url(r'^blog/', include('blog.urls'))
"""
from django.conf.urls import url
from django.contrib import admin
from app01 import views
urlpatterns = [
    url(r'^admin/', admin.site.urls),
    # 主页
    url(r'^$', views.home,name='home'),
    # 书籍展示页
    url(r'^book_list/', views.show_book,name='show'),
    # 书籍添加页
    url(r'^add_book/', views.add_book,name='add'),
    # 书籍编辑页
    url(r'^edit_book/(?P<edit_id>\d+)', views.edit_book,name='edit'),
    # 书籍删除页
    url(r'^delete_book/(\d+)', views.delete_book,name='delete'),
]

templates/add_book.html

{% extends 'home.html' %}

{% block content %}
    <h2 class="text-center">添加书籍</h2>
    <form action="" method="post">
        <p>书名:
            <input type="text" name="title" class="form-control">
        </p>
        <p>价格：
            <input type="text" name="price" class="form-control">
        </p>
        <p>出版日期：
            <input type="date" name="publish_time" class="form-control">
        </p>
        <p>出版社：
            <select name="publish" id="" class="form-control">
                {% for publish_obj in publish_queryset %}
                    <option value="{{ publish_obj.pk }}">{{ publish_obj.name }}</option>
                {% endfor %}
            </select>

        </p>
        <p>作者：
            <select name="authors" id="" class="form-control" multiple> # 多选
                {% for author_obj in author_queryset %}
                    <option value="{{ author_obj.pk }}">{{ author_obj.name }}</option>
                {% endfor %}

            </select>
        </p>
        <input type="submit" class="btn btn-primary">
    </form>
{% endblock %}

templates/book_list.html

{% extends 'home.html' %}

{% block content %}
    <div>
        <a href="{% url 'add' %}" class="btn btn-success">新增</a>
    </div>
    <br>
    <table class="table table-hover table-striped table-bordered">
        <thead>
            <tr>
                <th>序号</th>
                <th>书名</th>
                <th>价格</th>
                <th>出版日期</th>
                <th>出版社</th>
                <th>作者</th>
                <th>操作</th>
            </tr>
        </thead>
        <tbody>
            {% for book_obj in book_queryset %}
                <tr>
                    <td>{{ forloop.counter }}</td>
                    <td>{{ book_obj.title }}</td>
                    <td>{{ book_obj.price }}</td>
                    <td>{{ book_obj.publish_time|date:'Y-m-d' }}</td>
                    <td>{{ book_obj.publish.name}}</td>
                    <td>
                        {% for author_obj in book_obj.authors.all %}
                            {% if forloop.last %}
                                {{ author_obj.name }}
                            {% else %}
                                {{ author_obj.name }},
                            {% endif %}
                        {% endfor %}
                    </td>
                    <td>
                        <a href="{% url 'edit' book_obj.pk %}" class="btn btn-primary btn-sm">编辑</a>
                        <a href="{% url 'delete' book_obj.pk %}" class="btn btn-danger btn-sm">删除</a>
                    </td>
                </tr>
            {% endfor %}

        </tbody>
    </table>
    <nav aria-label="Page navigation" class="text-center">
  <ul class="pagination">
    <li>
      <a href="#" aria-label="Previous">
        <span aria-hidden="true">&laquo;</span>
      </a>
    </li>
    <li><a href="#">1</a></li>
    <li><a href="#">2</a></li>
    <li><a href="#">3</a></li>
    <li><a href="#">4</a></li>
    <li><a href="#">5</a></li>
    <li>
      <a href="#" aria-label="Next">
        <span aria-hidden="true">&raquo;</span>
      </a>
    </li>
  </ul>
</nav>

{% endblock %}

templates/edit_book.html

{% extends 'home.html' %}

{% block content %}
    <h2 class="text-center">编辑书籍</h2>
    <form action="" method="post">
        <p>书名：
            <input type="text" name="title" class="form-control" value="{{ edit_obj.title }}">
        </p>
        <p>价格：
            <input type="text" name="price" class="form-control" value="{{ edit_obj.price }}">
        </p>
        <p>出版日期
            <input type="date" name="publish_time" class="form-control" value="{{ edit_obj.publish_time|date:'Y-m-d' }}">
        </p>
        <p>出版社
            <select name="publish" id="" class="form-control">
                {% for publish_obj in publish_queryset %}
                    {% if edit_obj.publish == publish_obj %}
                        <option value="{{ publish_obj.pk }}" selected>{{ publish_obj.name }}</option>
                    {% else %}
                        <option value="{{ publish_obj.pk }}">{{ publish_obj.name }}</option>
                    {% endif %}
                {% endfor %}

            </select>
        </p>
        <p>作者：
            <select name="authors" id="" class="form-control" multiple>
                {% for author_obj in author_queryset %}
                    {% if author_obj in edit_obj.authors.all %}
                        <option value="{{ author_obj.pk }}" selected>{{ author_obj.name }}</option>
                    {% else %}
                        <option value="{{ author_obj.pk }}">{{ author_obj.name }}</option>
                    {% endif %}
                {% endfor %}
            </select>
        </p>
        <input type="submit" class="btn btn-warning">
    </form>
{% endblock %}

templates/home.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <script src="https://cdn.bootcss.com/jquery/3.4.1/jquery.min.js"></script>
    {% load static %}
    <link href="{% static 'bootstrap-3.3.7-dist/css/bootstrap.min.css' %}" rel="stylesheet">
    <script src="{% static 'bootstrap-3.3.7-dist/js/bootstrap.min.js' %}"></script>
</head>
<body>
<nav class="navbar navbar-inverse">
  <div class="container-fluid">
    <!-- Brand and toggle get grouped for better mobile display -->
    <div class="navbar-header">
      <button type="button" class="navbar-toggle collapsed" data-toggle="collapse" data-target="#bs-example-navbar-collapse-1" aria-expanded="false">
        <span class="sr-only">Toggle navigation</span>
        <span class="icon-bar"></span>
        <span class="icon-bar"></span>
        <span class="icon-bar"></span>
      </button>
      <a class="navbar-brand" href="#">BMS</a>
    </div>

    <!-- Collect the nav links, forms, and other content for toggling -->
    <div class="collapse navbar-collapse" id="bs-example-navbar-collapse-1">
      <ul class="nav navbar-nav">
        <li class="active"><a href="#">图书 <span class="sr-only">(current)</span></a></li>
        <li><a href="#">出版社</a></li>
        <li class="dropdown">
          <a href="#" class="dropdown-toggle" data-toggle="dropdown" role="button" aria-haspopup="true" aria-expanded="false">更多 <span class="caret"></span></a>
          <ul class="dropdown-menu">
            <li><a href="#">Action</a></li>
            <li><a href="#">Another action</a></li>
            <li><a href="#">Something else here</a></li>
            <li role="separator" class="divider"></li>
            <li><a href="#">Separated link</a></li>
            <li role="separator" class="divider"></li>
            <li><a href="#">One more separated link</a></li>
          </ul>
        </li>
      </ul>
      <form class="navbar-form navbar-left">
        <div class="form-group">
          <input type="text" class="form-control" placeholder="Search">
        </div>
        <button type="submit" class="btn btn-default">Submit</button>
      </form>
      <ul class="nav navbar-nav navbar-right">
        <li><a href="#">Link</a></li>
        <li class="dropdown">
          <a href="#" class="dropdown-toggle" data-toggle="dropdown" role="button" aria-haspopup="true" aria-expanded="false">Dropdown <span class="caret"></span></a>
          <ul class="dropdown-menu">
            <li><a href="#">Action</a></li>
            <li><a href="#">Another action</a></li>
            <li><a href="#">Something else here</a></li>
            <li role="separator" class="divider"></li>
            <li><a href="#">Separated link</a></li>
          </ul>
        </li>
      </ul>
    </div><!-- /.navbar-collapse -->
  </div><!-- /.container-fluid -->
</nav>
<div class="container-fluid">
    <div class="row">
        <div class="col-md-3">
            <div class="list-group">
              <a href="{% url 'home' %}" class="list-group-item active">
                首页
              </a>
              <a href="{% url 'show' %}" class="list-group-item">图书列表</a>
              <a href="#" class="list-group-item">出版社列表</a>
              <a href="#" class="list-group-item">作者列表</a>
              <a href="#" class="list-group-item">更多操作</a>
            </div>
        </div>
        <div class="col-md-9">
            <div class="panel panel-primary">
              <div class="panel-heading">
                <h3 class="panel-title">BMS</h3>
              </div>
              <div class="panel-body">
                  {% block content %}
                      <div class="jumbotron">
                      <h1>欢迎来到BMS系统</h1>
                      <p>请收藏网页持续关注</p>
                      <p><a class="btn btn-primary btn-lg" href="#" role="button">点这里</a></p>
                    </div>
                  {% endblock %}

              </div>
            </div>
        </div>
    </div>
</div>
</body>
</html>