Django目录介绍、路由系统、 ORM表的创建
Django目录介绍 django-admin startproject mysite 在终端创建目录 cd mysite python manage.py startapp app01 创建一个app project - app01 -migrations 和数据库相关,和modal相关 - admin Django自带后台管理相关配置 - modal 写类,根据类创建数据库表 - test 单元测试 - views 业务处理,业务可以分类 - app02 - app03 1. 路由系统(位置参数和形式参数不要不要混用,*args,**kwargs可以接收参数) url -> 函数 a. /login/ -> def login SEO权重不高 b. /add-user/(\d+)/ -> def add_user(request,a1) /add-user/(\d+)/(\d+)/ -> def add_user(request,a1,a2) 位置参数 c. /add-user/(?P\d+)/ -> def add_user(request,a1) 形式参数 url(r'^index/', views.index), 访问时必须index/这种形式 url(r'^index$', views.index), 访问时必须index这种形式 url(r'^index', views.index), 访问时index开头的任意字符串都可以访问 url(r'^index/(\d+).html', views.index), 访问时必须index/(\d+).html开头的这种形式 url(r'^', views.index) 没有匹配成功,设置默认html PS: 终止符: ^edit$ 伪静态 提高SEO权重 url(r'^edit/(\w+).html$', views.edit), d. 路由分发 urls.py中 导入from django.conf.urls import include url(r'^app01/', include('app01.urls')), 先在总路由匹配app路径,然后去该app下urls.py中去匹配路径 app01.urls.py url(r'^index.html$', views.index), e. 路由系统之别名反向生成url 根据名称可以反向生成URL 1. url(r'^index/', views.index,name="n1) 在Python代码中,在viws.py中 def index(request): from django.urls import reverse v = reverse('n1') print(v) #生成url路径/index/ url(r'^index/(\d+)/', views.index,name="n1) 在Python代码中,在viws.py中 def index(request,a1): from django.urls import reverse v = reverse('n1',args={ 451}) print(v) #生成url路径/index/451/ url(r'^index/(?P \d+)/', views.index,name="n1) 在Python代码中,在viws.py中 def index(request,a1): from django.urls import reverse v = reverse('n1',kwargs={ 'a1':1111}) print(v) #生成url路径/index/1111/ 2. 在路由文件中 url(r'^login/', views.login,name='m1') 在html文件中 { % url "m1" %} 提交就可以找到/login/路径 在路由文件中 url(r'^login/(\W)/', views.login,name='m1') url(r'^login/(\W).html$', views.login,name='m1') 在html文件中 { % for i in user_list %} { { i }}|编辑 { % endfor %} 提交就可以找到/login/i路径 提交就可以找到/login/i.html路径 3. ORM操作 ORM利用pymysql第三方工具连接数据库 默认:使用SQLlite 数据库 Http请求: url -> 视图(模板+数据) 步骤: 1. 创建数据库:在数据库创建70db 2. 在settings中设置 # DATABASES = { # 'default': { # 'ENGINE': 'django.db.backends.sqlite3', # 'NAME': os.path.join(BASE_DIR, 'db.sqlite3'), # } # } DATABASES = { 'default': { 'ENGINE': 'django.db.backends.mysql', 'NAME':'70db', 'USER': 'root', 'PASSWORD': '', 'HOST': 'localhost', 'PORT': 3306, } } 3. 在项目__init__.py中更换默认连接数据库的方式,MySQLDB(修改django默认连接mySQL方式) import pymysql pymysql.install_as_MySQLdb() 4.在app下的models.py下:创建表 from django.db import models class user_group(models.Model): title = models.CharField(max_length=32) class user_info(models.Model): id = models.BigAutoField(primary_key=True) #这一列不写也会自动生成 username=models.CharField(max_length=32) password=models.CharField(max_length=64) # age = models.IntegerField(null=True) #设置可以为空,创建表后插入这一列时可以这么设置 age = models.IntegerField(default=1) #默认生成ug_id,设置可以为空,创建表后插入这一列时可以这么设置 ug = models.ForeignKey("user_group",null=True) 5.在配置中注册app INSTALLED_APPS = [ 'django.contrib.admin', 'django.contrib.auth', 'django.contrib.contenttypes', 'django.contrib.sessions', 'django.contrib.messages', 'django.contrib.staticfiles', 'app01' ] 6.创建数据表 命令: python manage.py makemigrations python manage.py migrate
ORM表的操作
ORM操作表: 创建表 修改表 删除表 操作数据行: 增删改查 基于ORM实现组表操作 #新增 models.user_group.objects.create(title="销售部") models.user_info.objects.create(user='root',password='pwd',age=18,ug_id=1) 查找 group_list = models.user_group.objects.all() models.user_group.objects.all().count() 统计个数 group_list = models.user_group.objects.filter(id=1) group_list = models.user_group.objects.filter(id__gt=1) #大于 group_list = models.user_group.objects.filter(id__lt=1) #小于 print(group_list) #group_list是QuerySet类型,可以看成列表 group_list QuerySet类型(列表) QuerySet类型[obj,obj,obj] for row in group_list: print(row.id,row.title) models.user_info.objects.all() 删除 models.user_group.objects.filter(id=2).delete() 更新 models.user_group.objects.filter(id=2).update(title='公关部') 基于ORM实现员工表操作 1.增加 models.UserInfo.objects.create(user='root',password='123',age=10,ug_id=1) obj = models.UserGroup.objects.filter(id=1).first() #直接取一个值 models.UserInfo.objects.create(user='root',password='123',age=10,ug=obj) 2. 删除: models.UserInfo.objects.filter(id=2).delete() 3. 修改: models.UserInfo.objects.filter(id=2).update(title='公关部') 4. 查询: group_list = models.UserInfo.objects.all() group_list获取的是QuerySet,内部元素是UserInfo对象,每一个对象代指一行数据, 对象中如果包含ForeignKey,则代指与其关联表的一行数据 for row in group_list: print(row.user) print(row.age) print(row.ug_id) # 用户信息关联的部门ID print(row.ug.title) # 用户信息关联的部门名称
获取QuerySet(查询集)
# 获取QuerySet(查询集) 1.正向操作、反向操作(连表查询) QuerySet[obj,obj,obj] result = models.UserInfo.objects.all() for obj in result: print(obj.name,obj.age,obj.ut_id,obj.ut.title) 正向操作 UserInfo,ut是FK字段 - PS: 一个用户只有一个用户类型 obj = models.UserInfo.objects.all().first() print(obj.name,obj.age,obj.ut.title) 反向操作 UserType, 表名小写_set.all() - PS: 一个用户类型下可以有很多用户 obj = models.UserType.objects.all().first() print('用户类型',obj.id,obj.title) for row in obj.userinfo_set.all(): print(row.name,row.age) result = models.UserType.objects.all() for item in result: print(item.title,item.userinfo_set.filter(name='xx')) 2.数据获取多个数据时 1.列表查询集 [obj,obj,obj,] models.UserInfo.objects.all() models.UserInfo.objects.filter(id__gt=1) result = models.UserInfo.objects.all() for item in result: print(item.name,item.ut.title) 反向跨表: 1. 小写的表名_set obj = UserGroup.objects.all().first() result = obj.userinfo_set.all() [userinfo对象,userinfo对象,] 2.字典查询集 [{id:1,name:fd},{id:1,name:fd},{id:1,name:fd},] models.UserInfo.objects.all().values('id','name') models.UserInfo.objects.filter(id__gt=1).values('id','name') 无法跨表 result = models.UserInfo.objects.all().values('id','name') for item in result: print(item['id'],item['name']) 字典查询集正向跨表 __ result = models.UserInfo.objects.all().values('id','name',"ut__title") for item in result: print(item['id'],item['name'],item['ut__title']) 反向跨表: 2. 小写的表名 v = UserGroup.objects.values('id','title') v = UserGroup.objects.values('id','title','小写的表名称') v = UserGroup.objects.values('id','title','小写的表名称__age') 3.元组查询集 [(1,df),(2,'df')] models.UserInfo.objects.all().values_list('id','name') models.UserInfo.objects.filter(id__gt=1).values_list('id','name') 无法跨表 result = models.UserInfo.objects.all().values_list('id','name') for item in result: print(item[0],item[1]) 元组查询集正向跨表 __ result = models.UserInfo.objects.all().values_list('id','name',"ut__title") for item in result: print(item[0],item[1],item[2]) 反向跨表: 3. 小写的表名 v = UserGroup.objects.values_list('id','title') v = UserGroup.objects.values_list('id','title','小写的表名称') v = UserGroup.objects.values_list('id','title','小写的表名称__age')
select_related、prefetch_related连表查询
select_related()主要针一对一和多对一关系进行优化,使用SQL的JOIN语句进行优化
prefetch_related()对于多对多字段和一对多字段进行优化
参考:http://blog.csdn.net/secretx/article/details/43964607
select_related: 查询主动做连表,连表查询速度慢(适用外键对应的表数据量少时使用)q = models.UserInfo.objects.all().select_related('ut','gp')# select * from userinfo# select * from userinfo inner join usertype on ...for row in q: print(row.name,row.ut.title)prefetch_related: 不做连表,做多次查询(使用外键对应的表数据量大,数据频繁查询时使用)q = models.UserInfo.objects.all().prefetch_related('ut')# select * from userinfo;# Django内部:ut_id = [2,4]# select * from usertype where id in [2,4]for row in q: print(row.id,row.ut.title)
related_query_name和related_name的操作:
class Boy(models.Model): name=models.CharField(max_length=32) bpwd = models.IntegerField()class Girl(models.Model): nick = models.CharField(max_length=32) gpwd = models.IntegerField()class Love(models.Model): b=models.ForeignKey('Boy') g=models.ForeignKey('Girl') #可以如上这么写,会自动关联表的自增id,也可以指定表和关联id,如下: #b = models.ForeignKey(to='Boy',to_field='id') #g = models.ForeignKey(to='Girl',to_field='id')
class UserInfo(models.Model): nickname = models.CharField(max_length=32) username = models.CharField(max_length=32) password = models.CharField(max_length=64) gender_choices = ( (1,'男'), (2,'女'), ) gender = models.IntegerField(choices=gender_choices) class U2U(models.Model): #g = models.ForeignKey('UserInfo',related_query_name='boys') #b = models.ForeignKey('UserInfo',related_query_name='girls') g = models.ForeignKey('UserInfo',related_name='boys') b = models.ForeignKey('UserInfo',related_name='girls') 外键的操作:related_query_nameobj对象男.girls_set.all()obj对象女.boys_set.all()related_nameobj对象男.girls.all()obj对象女.boys.all() def test(request): #两种创建数据的方式: models.U2U.objects.create(b_id=2,g_id=6) models.U2U.objects.create(b_id=1,g_id=6) boy = models.UserInfo.objects.filter(gender=1,id=2).first() girl = models.UserInfo.objects.filter(gender=2,id=6).first() models.U2U.objects.create(b=boy,g=girl) #创建数据时可以放对象 外键的操作举例:UserInfo对象xz = models.UserInfo.objects.filter(id=1).first()# 和徐峥有关系的所有信息:U2U列表[U2U对象,2U对象,2U对象,]result = xz.girls.all()for u in result: # U2U对象 print(u.g.nickname)
v.query 查询原生sql语句
一对一操作的正反向:# obj = models.Blog.objects.filter(site=site).first() # print(obj.user.nickname) # obj = models.UserInfo.objects.filter(username='sw').first() # print(obj.blog.site) onetoone 反向操作时
多对多操作:有外键的情况查询操作
class Boy(models.Model): name = models.CharField(max_length=32)class Girl(models.Model): nick = models.CharField(max_length=32)class Love(models.Model): b = models.ForeignKey('Boy') g = models.ForeignKey('Girl') class Meta: #联合唯一索引 unique_together = [ ('b','g'), ]1. 和方少伟有关系的姑娘obj = models.Boy.objects.filter(name='方少伟').first()love_list = obj.love_set.all()for row in love_list: print(row.g.nick)love_list = models.Love.objects.filter(b__name='方少伟')for row in love_list: print(row.g.nick)连表操作:love_list = models.Love.objects.filter(b__name='方少伟').values('g__nick')for item in love_list: print(item['g__nick'])连表操作:love_list = models.Love.objects.filter(b__name='方少伟').select_related('g')for obj in love_list: print(obj.g.nick)
多对多操作:ManyToManyField、杂交、自定义关系表
1. ManyToManyField class Boy(models.Model): name = models.CharField(max_length=32) m = models.ManyToManyField('Girl') #django内置方式这一行会生成第三张关系表,即app01_boy_m,只能生成三列,如果有多行信息,自己写在第三张表 #m = models.ManyToManyField('Girl',through="Love",through_fields=('b','g',)) #杂交,如果这样写就只生成LOVE表 class Girl(models.Model): nick = models.CharField(max_length=32) #自定义关系表 #class Love(models.Model): # b = models.ForeignKey('Boy') # g = models.ForeignKey('Girl') # class Meta: #联合唯一索引 # unique_together = [ # ('b','g'), # ] 增加: obj = models.Boy.objects.filter(name='方少伟').first() print(obj.id,obj.name) obj.m.add(2) obj.m.add(2,4) obj.m.add(*[1,]) 删除: obj.m.remove(1) obj.m.remove(2,3) obj.m.remove(*[4,]) 覆盖修改: obj.m.set([1,]) q = obj.m.all() # [Girl对象] print(q) obj = models.Boy.objects.filter(name='方少伟').first() girl_list = obj.m.all() obj = models.Boy.objects.filter(name='方少伟').first() girl_list = obj.m.all() girl_list = obj.m.filter(nick='小鱼') print(girl_list) 删除第三张表的数据: obj = models.Boy.objects.filter(name='方少伟').first() obj.m.clear() 反向操作: obj = models.Girl.objects.filter(nick='小鱼').first() print(obj.id,obj.nick) v = obj.boy_set.all() print(v) 2.杂交:#m = models.ManyToManyField('Girl',through="Love",through_fields=('b','g',))obj = models.Boy.objects.filter(name='方少伟').first()# obj.m.add(1) 因为有ManyToManyField,所以不行,因为可能第三张表还有其他列# obj.m.remove(1) 因为有ManyToManyField,所以不行,因为可能第三张表还有其他列# obj.m.clear() 可以v = obj.m.all() 可以print(v) 3. 自定义关系表
多对多操作,有无第三张表的情况:
# 自己反向关联,需要通多中间的表 # v= models.Article.objects.filter(blog=blog,article2tag__tag=val) # 通过M2M字段,直接关联到另一张表,跳过中间件 # v= models.Article.objects.filter(blog=blog,tags__nid=val)
class Article(models.Model): nid = models.BigAutoField(primary_key=True) title = models.CharField(verbose_name='文章标题',max_length=128) summary = models.CharField(verbose_name='文章简介',max_length=255) read_count = models.IntegerField(default=0) comment_count = models.IntegerField(default=0) up_count = models.IntegerField(default=0) down_count = models.IntegerField(default=0) create_time = models.DateTimeField(verbose_name='创建时间',auto_now_add=True) blog = models.ForeignKey(verbose_name='所属博客',to='Blog',to_field='nid') category = models.ForeignKey(verbose_name='文章类型',to='Category',to_field='nid',null=True) type_choices=[ (1,'Python'), (2,'Linux'), (3,'OpenStack'), (4,'GoLang'), ] article_type_id = models.IntegerField(choices=type_choices,default=None) tags = models.ManyToManyField( to = 'Tag', through='Article2Tag', through_fields=('article','tag'), )class Tag(models.Model): nid = models.AutoField(primary_key=True) title = models.CharField(verbose_name='标签名称',max_length=32) blog = models.ForeignKey(verbose_name='所属博客',to='Blog',to_field='nid')class Article2Tag(models.Model): article = models.ForeignKey(verbose_name='文章',to='Article',to_field='nid') tag = models.ForeignKey(verbose_name='标签',to='Tag',to_field='nid') class Meta: unique_together =[ ('article','tag'), ]
""" 1. 分类 category_list = models.Article.objects.filter(blog=blog).values('category_id','category__title',).annotate(c=Count('nid')) 2. 标签 tag_list = models.Article2Tag.objects.filter(tag__blog=blog).values('tag_id','tag__title').annotate(c=Count('id')) 3. 时间 # MySQL # date_list = models.Article.objects.filter(blog=blog).extra(select={ 'c': "date_format(create_time,'%%Y-%%m')"}).values('c').annotate(ct=Count('nid')) # SQLlite # date_list = models.Article.objects.filter(blog=blog).extra(select={ 'c': "strftime('%%Y-%%m',create_time)"}).values('c').annotate(ct=Count('nid')) """ mysql: date_list = models.Article.objects.filter(blog=blog).values("date_format(create_time,'%%Y-%%m')").annotate(ct=Count('nid')) #错误,values里面参数只能是列名 # date_list = models.Article.objects.filter(blog=blog).extra(select={ 'c': "date_format(create_time,'%%Y-%%m')"}).values('c').annotate(ct=Count('nid')
from django.db.models import functions # models.Article.objects.filter(blog=blog).annotate(x=functions.Extract('create_time','YEAR_MONTH')) # models.Article.objects.filter(blog=blog).annotate(x=functions.ExtractYear('create_time')) """ nid xx create_time x 1 x 2018-09-01 11:11 201809 2 x 2018-09-01 11:11 2018 """ # models.Article.objects.filter(blog=blog).annotate(x=functions.TruncMonth('create_time')) # models.Article.objects.filter(blog=blog).annotate(x=functions.Trunc('create_time','')) """ nid xx create_time x 1 x 2018-09-01 11:11 09 """ # from django.db.models import FloatField # from django.db.models import Value # v = models.Article.objects.annotate(c=functions.Cast('nid', FloatField())) #类型转换 # v = models.Article.objects.annotate(c=functions.Coalesce('title','summary')) #找到第一个非空 # v = models.Article.objects.annotate(c=functions.Concat('nid','title','summary')) #拼接 # v = models.Article.objects.annotate(c=functions.Concat('nid','title','summary',Value('666'))) # v = models.Article.objects.annotate(c=functions.Greatest('nid','num')) #取较大的值 # v = models.Article.objects.annotate(c=functions.Length('title')) #获取长度 # v = models.Article.objects.annotate(c=functions.Substr('title',1,1)) #取自定长度的字符串,只能从第一位开始
进阶操作:
# 1.增删改查 # 2. 一般: # models.UserInfo.objects.filter(id__gt=1) 大于 # models.UserInfo.objects.filter(id__lt=1) 小于 # models.UserInfo.objects.filter(id__gte=1) 大于等于 # models.UserInfo.objects.filter(id__lte=1) 小于等于 # models.UserInfo.objects.filter(id__in=[1,2,3]) # models.UserInfo.objects.filter(id__range=[1,2]) # models.UserInfo.objects.filter(name__startswith='xxxx') 以xxxx开头 # models.UserInfo.objects.filter(name__contains='xxxx') 内容包含xxxx # models.UserInfo.objects.filter(name__icontains='xxxx') 内容包含xxxx,不区分大小写 # models.UserInfo.objects.exclude(id=1) 不等于exclude models.UserInfo.filter(age__isnull=True) 数据为空也可以查询 # 3. 排序 user_list = models.UserInfo.objects.all().order_by('-id','name') 反向排序 user_list = models.UserInfo.objects.all().order_by('id','name') 正向排序 # 4. 分组 from django.db.models import Count,Sum,Max,Min 分组: v =models.UserInfo.objects.values('ut_id').annotate(xxxx=Count('id')) print(v.query) 结果: #SELECT "app01_userinfo"."ut_id", COUNT("app01_userinfo"."id") AS "xxxx" FROM "app01_userinfo" GROUP BY "app01_userinfo"."ut_id" 分组后再筛选: v =models.UserInfo.objects.values('ut_id').annotate(xxxx=Count('id')).filter(xxxx__gt=2) print(v.query) 结果: SELECT "app01_userinfo"."ut_id", COUNT("app01_userinfo"."id") AS "xxxx" FROM "app01_userinfo" GROUP BY "app01_userinfo"."ut_id" HAVING COUNT("app01_userinfo"."id") > 2 v =models.UserInfo.objects.filter(id__gt=2).values('ut_id').annotate(xxxx=Count('id')).filter(xxxx__gt=2) print(v.query) 结果: SELECT "app01_userinfo"."ut_id", COUNT("app01_userinfo"."id") AS "xxxx" FROM "app01_userinfo" WHERE "app01_userinfo"."id" > 2 GROUP BY "app01_userinfo"."ut_id" HAVING COUNT("app01_userinfo"."id") > 2 5. F,更新时用于获取原来的值 from django.db.models import F,Q 更新数据库一列: models.UserInfo.objects.all().update(age=F("age")+1) 6. Q,用于构造复杂查询条件 # 应用一: # models.UserInfo.objects.filter(Q(id__gt=1)) # models.UserInfo.objects.filter(Q(id=8) | Q(id=2)) # models.UserInfo.objects.filter(Q(id=8) & Q(id=2)) # 应用二: models.UserInfo.objects.filter(id=1,name='root') condition = { 'id':1, 'name': 'root' } models.UserInfo.objects.filter(**condition) 自动添加Q condition_dict = { 'k1':[1,2,3,4], 'k2':[1,], } con = Q() for k,v in condition_dict.items(): q = Q() q.connector = 'OR' for i in v: q.children.append(('id', i)) con.add(q,