Django(4)--mysql操作

目录

路由优化配置

  • 拆分为多个应用。在app中创建自己的urls
  • urlpatterns路由规则列表
  • 在根urls中进行子路由的包含
  • 子路由
    • 根路由规则+子路由规则
djangoadmin startapp app02
  • settings.py 注册新项目
INSTALLED_APPS = [
    'django.contrib.admin',
    'django.contrib.auth',
    'django.contrib.contenttypes',
    'django.contrib.sessions',
    'django.contrib.messages',
    'django.contrib.staticfiles',
    'app01',
    'app02'
]
  • app02创建urls.py
from django.conf.urls import url
from app02 import views
urlpatterns = [
    url(r'^index/',views.index)
]
  • app02/views.py
def index(request):
    return HttpResponse('app02 index')
  • bookmanager/urls.py
from django.conf.urls import url,include
from django.contrib import admin
#Include语法，来将单独的页面包含到当前模板页面中,路由转发
url(r'^app02/',include('app02.urls'))

django--MySQL

  • models 使用了ORM技术
    • object relational Mapping 对象关系映射
  • 将业务逻辑进行了一个解耦合
    • object.save()
    • object.delete()
  • 关系型数据库
    • DDL
    • 通过models定义实现，数据表的定义
  • 数据操作
    • 增删改查
    • 存储
      • save()
    • 查询
      • 查所有 objects.all()
      • 查单个 objects.get(pk=2)
    • 更新
      • 基于查询的
      • 查好的对象，修改属性，然后save() #基于主键，主键存在就是更新，主键不存在就是创建
    • 删除
      • 基于查询的
      • 调用delete()
  • models.py
from django.db import models
class Student(models.Model):#继承Django的models
    s_name = models.CharField(max_length=16)
    s_age = models.IntegerField(default=1) #default=1默认值
  • python命令，将模块刷到数据库
#生成迁移文件
E:python_datapy27ookmanager>python manage.py makemigrations
Migrations for 'app01':
  app01migrations003_auto_20191121_1645.py
    - Create model Student
    - Delete model test
    
#迁移
E:python_datapy27ookmanager>python manage.py migrate
Operations to perform:
  Apply all migrations: admin, app01, auth, contenttypes, sessions
Running migrations:
  Applying contenttypes.0001_initial... OK
  Applying auth.0001_initial... OK
  ....
  • app01/urls.py
from django.conf.urls import url
from app01 import views
urlpatterns = [
    url(r'^index/',views.index),
    url(r'addstudent/',views.add_student)
]
  • app01/views.py
from django.shortcuts import render,HttpResponse,redirect
from app01 import models
from app01.models import Student
def add_student(request):
    student = Student()
    student.s_name='jrrey'
    student.save()
    return HttpResponse('Add successfully')

  • 到数据库刷新查看，可以看见学生已经添加

  • 生成新的随机人员

def add_student(request):
    student = Student()
    student.s_name= 'jerry%d' % random.randrange(100)
    student.save()
    return HttpResponse('add successfully %s' % student.s_name)

访问 http://127.0.0.1:8000/app01/addstudent/

templates模板展示

  • templates两种配置
  1. 第一种在app01中进行模板配置，app01/templatesm目录
    • 如果想让代码自动提示，将文件夹标记为模板文件夹
  2. 在项目目录中创建模板配置（开发中使用，便于模板继承）
    • 在项目中创建templates并标记
    • 需要在settings中进行注册
  • bookmanager emplatesstudent_list.html
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>student_list</title>
</head>
<body>
<h2>hello</h2>
<h3>{{ hobby }}</h3>


</body>
</html>

展示学生

  • 展示学生列表1
    app01/urls.py
from django.conf.urls import url
from django.contrib import admin
from  app01 import  views

urlpatterns = [
    url(r'^admin/', admin.site.urls),
    #出版社的展示
    # url(r'^publishare_list/',views.publishare_list)
    # url()
    url(r'^login/',views.login),
    url(r'index/',views.index),
    url(r'addstudent/',views.add_student),
    url(r'getstudent/',views.get_student),
]
  • app01/views.py
def get_student(request):
    students = Student.objects.all() #orm为提供学生操作的一个入口
    for student in students:
        print(student.s_name)
    return HttpResponse('student list')
  • 展示学生列表2
def get_student(request):
    students = Student.objects.all() #orm为提供学生操作的一个入口
    for student in students:
        print(student.s_name)
        context = {
            "hobby":"play games",
            "eat":"meat" #如果没在HTML中定义就不会刷出来
        } #往模板中传的数据，是个字典
    return render(request,'student_list.html',context=context)

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>student_list</title>
</head>
<body>
<h2>hello</h2>
<h3>{{ hobby }}</h3>
<h3>{{ eat }}</h3>


</body>
</html>

def get_student(request):
    students = Student.objects.all() #orm为提供学生操作的一个入口
    for student in students:
        print(student.s_name)
    context = {
        "hobby":"play games",
        "eat":"meat", #如果没在HTML中定义就不会刷出来
        "students":students
    } #往模板中传的数据，是个字典
    return render(request,'student_list.html',context=context)

<h1>student list</h1>
<hr>
<ul>
    {% for student in students %}
        <li>{{ student.s_name }}</li>
    {% endfor %}
</ul>
</body>
</html>

修改学生名字

urlpatterns = [
    url(r'^admin/', admin.site.urls),
    url(r'addstudent/',views.add_student),
    url(r'getstudent/',views.get_student),
    url(r'updatestudent/',views.update_student),
]

def update_student(request):
    student = Student.objects.get(pk=2) #get获取单个对象，跟个条件pk等于2，pk=2 就是primary主键=2
    student.s_name = 'jack'
    student.save()
    return HttpResponse('student update successfully')

删除学生

def delete_student(request):
    student = Student.objects.get(pk=3)
    student.delete()
    return HttpResponse('student delete successfully')

mysql

  • 原始表迁移到新数据库
python manage.py migrate
  • 连接 mysqlclient
    • python2,3都能直接使用
    • 致命缺点
      • 对mysql安装有要求，必须指定位置存在配置文件
  • python-mysql
    • python2支持很好
    • python3 不支持
  • pymysql
    • python2,3都支持
    • 可以伪装成前两个库
pip install pymysql -i源
  • bookmanagerookmanager_init_.py #程序最先调用,放驱动
import pymysql
  • 测试，增加学生看看能不能刷到数据库
http://127.0.0.1:8000/app01/addstudent/
  • 加载模板、渲染模板，好处是支持模板语言
  • views.py
from django.shortcuts import render,redirect,HttpResponse
from django.template import loader

def three_index(request):
    threeindex = loader.get_template('three.html') #加载
    ret = threeindex.render() #渲染成字符串
    print(ret)
    return HttpResponse(ret)
    

def three_index(request):
    threeindex = loader.get_template('three.html')
    context = {
        "student_name":"Sunck",
    }
    ret = threeindex.render(context=context)
    print(ret)
    return HttpResponse(ret)

python manage.py shell

  • (django的shell，一般用于调试)
  • 集成了python环境的shell终端
  • 通常在终端中做一些调试工作
E:py27Django_projectookmanager>python manage.py shell
Python 3.7.4 (tags/v3.7.4:e09359112e, Jul  8 2019, 20:34:20) [MSC v.1916 64 bit (AMD64)] on win32
Type "help", "copyright", "credits" or "license" for more information.
(InteractiveConsole)
>>> from app01.models import Student
>>> students = Student.objects.all()
>>> for student in students:
... print (student.s_name)
##创建学生
>>> student = Student()
>>> student.s_name = 'Sunck'
>>> student.save()

如何看待bug

  • 看日志
    • 先看第一条
    • 再看最后一条
  • 梳理思路
    • 程序在哪一个位置和预期出现偏差

表关系

  • 1对1 （外键约束）
  • 1对多（外键）
  • 多对多（额外产生关系表）

级联

  • app02/models.py（新类）
class Grade(models.Model):
    g_name = models.CharField(max_length=32) 
    
class Student(models.Model):
    s_name = models.CharField(max_length=16)
    s_grade = models.ForeignKey(Grade,on_delete=models.CASCADE,)  #外键到班级

python manage.py makemigrations
python manage.py migrate
  • 报错
E:py27Django_projectookmanager>python manage.py makemigrations app02
Traceback (most recent call last):
  File "manage.py", line 21, in <module>
    main()
  File "manage.py", line 17, in main
    execute_from_command_line(sys.argv)
  File "E:软件python3libsite-packagesdjangocoremanagement\__init__.py", line 381, in execute_from_command_line
    utility.execute()
  File "E:软件python3libsite-packagesdjangocoremanagement\__init__.py", line 357, in execute
    django.setup()
  File "E:软件python3libsite-packagesdjango\__init__.py", line 24, in setup
    apps.populate(settings.INSTALLED_APPS)
  File "E:软件python3libsite-packagesdjangoapps
egistry.py", line 114, in populate
    app_config.import_models()
  File "E:软件python3libsite-packagesdjangoappsconfig.py", line 211, in import_models
    self.models_module = import_module(models_module_name)
  File "E:软件python3libimportlib\__init__.py", line 127, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 1006, in _gcd_import
  File "<frozen importlib._bootstrap>", line 983, in _find_and_load
  File "<frozen importlib._bootstrap>", line 967, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 677, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 728, in exec_module
  File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
  File "E:py27Django_projectookmanagerapp02models.py", line 7, in <module>
    class Student(models.Model):
  File "E:py27Django_projectookmanagerapp02models.py", line 9, in Student
    s_grade = models.ForeignKey(Grade)
TypeError: __init__() missing 1 required positional argument: 'on_delete'

原因：
在django2.0后，定义外键和一对一关系的时候需要加on_delete选项，此参数为了避免两个表里的数据不一致问题，不然会报错：
TypeError: __init__() missing 1 required positional argument: 'on_delete'
  • 添加班级 app02_grade
+----+-------------+
| id | g_name      |
+----+-------------+
|  1 | GP-python-1 |
|  2 | python1887  |
|  3 | python1888  |
|  4 | python1809  |
+----+-------------+
  • 添加学生 app02_student
+----+--------+------------+
| id | s_name | s_grade_id |
+----+--------+------------+
|  1 | Sunck  |          1 |
|  2 | Tom    |          1 |
|  3 | Jack   |          1 |
|  4 | Rose   |          2 |
|  5 | marry  |          3 |
+----+--------+------------+
  • bookmanager/urls.py
from django.conf.urls import url,include
from django.contrib import admin
from app01 import views
from app02 import views
urlpatterns = [
    url('admin/', admin.site.urls),
    # url('login/',views.login),
    url('app01/',include('app01.urls')),
    url('app02/',include('app02.urls'))
]
  • app02/urls.py
from django.conf.urls import url
from app02 import views
urlpatterns = [
  
    # url(r'threeindex/',views.three_index),
    url(r'getgrade/',views.get_grate),
    url(r'getstudents/',views.get_students),
]
  • app02/views.py
from django.shortcuts import render,HttpResponse,redirect
from app02.models import Student
from  app02 import models
from app02.models import Grade
# Create your views here.


def get_grate(request):
    student = Student.objects.get(pk=1)
    grate = student.s_grade
    return HttpResponse("Grate %s"%grate.g_name)
# 查询时先查的student，通过student调出grate，这就是简单的数据级联

def get_students(request):
    grate = Grade.objects.get(pk=1)
    students = grate.student_set.all()
    context={
        "students":students
    }
    return render(request,'student_app02_list.html',context=context)
  • app02/temlates/student_app02_list.html
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>student_list</title>
</head>
<body>
<h3>student list</h3>
<ul>
    {% for student in students %}
        <li>{{ student.s_name }}</li>
    {% endfor %}

</ul>
</body>
</html>
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原文地址：https://www.cnblogs.com/yihutu/p/11937274.html