Django基于ORM操作数据库的方法详解

vim settings #HelloWorld/HelloWorld目录下

DATABASES = {  'default': {    'ENGINE': 'django.db.backends.mysql', #mysql数据库中第一个库test    'NAME': 'test',    'USER': 'root',    'PASSWORD': '123456',    'HOST':'127.0.0.1',    'PORT':'3306',  },  'article': {    'ENGINE': 'django.db.backends.mysql', # mysql数据库中第二个库test2    'NAME': 'test2',    'USER': 'root',    'PASSWORD': '123456',    'HOST':'127.0.0.1',    'PORT':'3306',  }}

django-admin.py startapp blog ##HelloWorld/目录下建立网站app，我建了两个app（blog和article）

vim settings ##/HelloWorld/HelloWorld目录下

INSTALLED_APPS = [  'django.contrib.admin',  'django.contrib.auth',  'django.contrib.contenttypes',  'django.contrib.sessions',  'django.contrib.messages',  'django.contrib.staticfiles',  'blog',  'article',]

vim models.py ##blog目录下

from django.db import models# Create your models here.class Teacher(models.Model):  id = models.IntegerField(primary_key=True)  name = models.CharField(max_length=50)  class Meta:    db_table = 'teacher'#默认库test中建立名为teacher的表。字段就是id和name

python manage.py migrate ##建立Django系统表，首次运行即可python manage.py makemigrations ##生成迁移计划，每次加表或字段时都运行生成计划python manage.py migrate ##同步用户定义的表

vim models.py #blog目录下，新建个表测试下，可以在添加或修改删除几个字段试试

class Student(models.Model):  id = models.IntegerField(primary_key=True)  name = models.CharField(max_length=50)  student_number = models.CharField(default="",max_length=50)  class Meta:    db_table = 'student'

cd article #进入article目录vim models.py #article目录下

from django.db import modelsclass Author(models.Model):  id = models.IntegerField(primary_key=True)  name = models.CharField(max_length=50)  author_ids = models.CharField(max_length=50)  class Meta:    db_table = 'author'    app_label = 'article' ##对应的article这个应用，名字要一致

python manage.py makemigrations article ##生成同步计划##对article应用执行同步，同步到 article（settings中的配置，对应test2）对应的数据库中.python migrate article --database article ##执行计划，必须加--database 指定要同步的库

cd blog #进入blog目录下vim models.py ##blog目录下，在文件中增加一个表，注意后边app_label

class Group(models.Model):  id = models.IntegerField(primary_key=True)  group_name = models.CharField(max_length=50)  class Meta:    db_table = 'group'    app_label = 'article' ##必须指定这个库

python manage.py makemigrations article ##生成同步计划，虽说改的是blogpython migrate article --database article ##执行计划，虽说改的是blog

vim view.py ##blog目录下，添加下列代码

from blog.models import Teacherdef orm_handle_db(request):  test1 = Teacher(id=1,name='runoob',teacher_number='10') ##定义数据  test1.save() ##保存  return render_to_response('orm_handle_db.html')

vim urls.py ##blog目录下

from django.conf.urls import urlfrom blog import viewsurlpatterns = [  url(r'^hello/$', views.hello),  url(r'^search/$', views.search),  url(r'^post_search/$', views.post_search),  url(r'^search_submit$', views.search_submit),  url(r'^post_search_submit$', views.post_search_submit),  url(r'^db_handle/$', views.db_handle),  url(r'^orm_handle_db/$', views.orm_handle_db), ##这里配置好]

vim orm_handle_db.html ##blog/templates目录下

vim settings.py ##HelloWorld/HelloWorld目录下，添加下面两项

DATABASES_APPS_MAPPING = {  'blog': 'default',  'article': 'article',    }DATABASE_ROUTERS = ['HelloWorld.database_app_router.DatabaseAppsRouter']

vim database_app_router.py ##配置路由 ,HelloWorld/HelloWorld/目录下。直接粘贴

from django.conf import settingsclass DatabaseAppsRouter(object):def db_for_read(self, model, **hints):app_label = model._meta.app_labelif app_label in settings.DATABASES_APPS_MAPPING:res = settings.DATABASES_APPS_MAPPING[app_label]print(res)return resreturn Nonedef db_for_write(self, model, **hints):app_label = model._meta.app_labelif app_label in settings.DATABASES_APPS_MAPPING:return settings.DATABASES_APPS_MAPPING[app_label]return Nonedef allow_relation(self, obj1, obj2, **hints):db_obj1 = settings.DATABASES_APPS_MAPPING.get(obj1._mata.app_label)db_obj2 = settings.DATABASES_APPS_MAPPING.get(obj2._mata.app_label)if db_obj1 and db_obj2:if db_obj1 == db_obj2:return Trueelse:return Falsereturn Nonedef db_for_migrate(self, db, app_label, model_name=None, **hints):if db in settings.DATABASES_APPS_MAPPING.values():return settings.DATABASES_APPS_MAPPING.get(app_label) == dbelif app_label in settings.DATABASES_APPS_MAPPING:return Falsereturn None

vim views.py #blog目录下，添加下方代码

from blog.models import Teacher,Group##这是第8步没有的def orm_handle_db(request):  test1 = Teacher(id=1,name='runoob',teacher_number='10')  test2 = Group(id=1,group_name='runoob') ##这是第8步没有的  test1.save()  test2.save()##这是第8步没有的  return render_to_response('orm_handle_db.html')