注意：
本实验是接着 《Django 数据展示（多对多版）》而继续的
正文：
步骤目录：
步骤一：在没有自定义 manager 管理器的情况下尝试一次性完成多对多表数据的插入
1.1 进入相应的 Django 环境
1.2 在没有自定义 manager 管理器的情况下尝试一次性完成多对多表数据的插入
1.3 退出相应的 Django 环境
步骤二：确认要插入的数据和预期的一致（可选）
2.1 创建一个自定义 manager 管理器的类
2.2 进入相应的 Django 环境
2.3 确认要插入的数据和预期的一致
2.4 退出相应的 Django 环境
步骤三：一次性完成多对多表数据的插入
3.1 创建一个自定义 manager 管理器的类
3.2 进入相应的 Django 环境
3.3 一次性完成多对多表数据的插入
具体的操作步骤：
步骤一：在没有自定义 manager 管理器的情况下尝试一次性完成多对多表数据的插入
1.1 进入相应的 Django 环境
>>> import os,django
>>> os.environ.setdefault("DJANGO_SETTINGS_MODULE", "mysite.settings")
'mysite.settings'
>>> django.setup()
>>> from user.models import *
1.2 在没有自定义 manager 管理器的情况下尝试一次性完成多对多表数据的插入
>>> Student.objects.create(sname='lili',clazz='Class1',course=('Python','Shell'))
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "/Users/zhumingyu/Code/Django/mtwo/django_env/lib/python3.8/site-packages/django/db/models/manager.py", line 85, in manager_method
return getattr(self.get_queryset(), name)(*args, **kwargs)
File "/Users/zhumingyu/Code/Django/mtwo/django_env/lib/python3.8/site-packages/django/db/models/query.py", line 451, in create
obj = self.model(**kwargs)
File "/Users/zhumingyu/Code/Django/mtwo/django_env/lib/python3.8/site-packages/django/db/models/base.py", line 503, in __init__
raise TypeError("%s() got an unexpected keyword argument '%s'" % (cls.__name__, kwarg))
TypeError: Student() got an unexpected keyword argument 'clazz'
（
补充：
（1）这里数据插入失败
（2）按正常顺序应该是先插入班级 clazz，之后再插入学生 student，之后再插入课程 course，之后再去插入中间表
）
1.3 退出相应的 Django 环境
>>> quit();
步骤二：确认要插入的数据和预期的一致（可选）
2.1 创建一个自定义 manager 管理器的类
将 mysite/test/models.py 中的以下内容:
......
class Clazz(models.Model):
cno = models.AutoField(primary_key=True)
cname = models.CharField(max_length=30)
def __str__(self):
return u'Clazz:%s'%self.cname
class Course(models.Model):
course_no = models.AutoField(primary_key=True)
course_name = models.CharField(max_length=30)
def __str__(self):
return u'Course:%s'%self.course_name
class Student(models.Model):
sno = models.AutoField(primary_key=True)
sname = models.CharField(max_length=30)
cls = models.ForeignKey(Clazz,on_delete=models.CASCADE)
cour = models.ManyToManyField(Course)
def __str__(self):
return u'Student:%s'%self.sname
# Get class object according to class name
def getCls(cname):
try:
cls = Clazz.objects.get(cname=cname)
except Clazz.DoesNotExist:
cls = Clazz.objects.create(cname=cname)
return cls
def getCourseList(*coursenames):
courseList = []
for cn in coursenames:
try:
c = Course.objects.get(course_name=cn)
except Course.DoesNotExist:
c = Course.objects.create(course_name=cn)
courseList.append(c)
return courseList
def registerStu(sname,cname,*coursenames):
#1. Get class objects
cls = getCls(cname)
#2. Gets the list of course objects
courseList = getCourseList(*coursenames)
#3. Insert student table data
try:
stu = Student.objects.get(sname=sname)
except Student.DoesNotExist:
stu = Student.objects.create(sname=sname,cls=cls)
#4. Insert intermediate table data
stu.cour.add(*courseList)
return True
修改为：
......
from django.db import models
from django.db.models.manager import Manager
# Create your models here.
class Clazz(models.Model):
cno = models.AutoField(primary_key=True)
cname = models.CharField(max_length=30)
def __str__(self):
return u'Clazz:%s'%self.cname
class Course(models.Model):
course_no = models.AutoField(primary_key=True)
course_name = models.CharField(max_length=30)
def __str__(self):
return u'Course:%s'%self.course_name
class CustomManager(Manager):
def create(self, **kwargs):
print(kwargs)
class Student(models.Model):
sno = models.AutoField(primary_key=True)
sname = models.CharField(max_length=30)
cls = models.ForeignKey(Clazz,on_delete=models.CASCADE)
cour = models.ManyToManyField(Course)
objects = CustomManager()
def __str__(self):
return u'Student:%s'%self.sname
# Get class object according to class name
def getCls(cname):
try:
cls = Clazz.objects.get(cname=cname)
except Clazz.DoesNotExist:
cls = Clazz.objects.create(cname=cname)
return cls
def getCourseList(*coursenames):
courseList = []
for cn in coursenames:
try:
c = Course.objects.get(course_name=cn)
except Course.DoesNotExist:
c = Course.objects.create(course_name=cn)
courseList.append(c)
return courseList
def registerStu(sname,cname,*coursenames):
#1. Get class objects
cls = getCls(cname)
#2. Gets the list of course objects
courseList = getCourseList(*coursenames)
#3. Insert student table data
try:
stu = Student.objects.get(sname=sname)
except Student.DoesNotExist:
stu = Student.objects.create(sname=sname,cls=cls)
#4. Insert intermediate table data
stu.cour.add(*courseList)
return True
（补充：这里以添加一个显示自己所有键值对的 CustomManager(Manager) 对象并在 Student 类中使用 objects 调用为例）
2.2 进入相应的 Django 环境
>>> import os,django
>>> os.environ.setdefault("DJANGO_SETTINGS_MODULE", "mysite.settings")
'mysite.settings'
>>> django.setup()
>>> from user.models import *
2.3 确认要插入的数据和预期的一致
>>> Student.objects.create(sname='lili',clazz='Class1',course=('Python','Shell'))
{'sname': 'lili', 'clazz': 'Class1', 'course': ('Python', 'Shell')}
2.4 退出相应的 Django 环境
>>> quit();
步骤三：一次性完成多对多表数据的插入
3.1 创建一个自定义 manager 管理器的类
将 mysite/test/models.py 中的以下内容:
......
class Clazz(models.Model):
cno = models.AutoField(primary_key=True)
cname = models.CharField(max_length=30)
def __str__(self):
return u'Clazz:%s'%self.cname
class Course(models.Model):
course_no = models.AutoField(primary_key=True)
course_name = models.CharField(max_length=30)
def __str__(self):
return u'Course:%s'%self.course_name
class Student(models.Model):
sno = models.AutoField(primary_key=True)
sname = models.CharField(max_length=30)
cls = models.ForeignKey(Clazz,on_delete=models.CASCADE)
cour = models.ManyToManyField(Course)
def __str__(self):
return u'Student:%s'%self.sname
# Get class object according to class name
def getCls(cname):
try:
cls = Clazz.objects.get(cname=cname)
except Clazz.DoesNotExist:
cls = Clazz.objects.create(cname=cname)
return cls
def getCourseList(*coursenames):
courseList = []
for cn in coursenames:
try:
c = Course.objects.get(course_name=cn)
except Course.DoesNotExist:
c = Course.objects.create(course_name=cn)
courseList.append(c)
return courseList
def registerStu(sname,cname,*coursenames):
#1. Get class objects
cls = getCls(cname)
#2. Gets the list of course objects
courseList = getCourseList(*coursenames)
#3. Insert student table data
try:
stu = Student.objects.get(sname=sname)
except Student.DoesNotExist:
stu = Student.objects.create(sname=sname,cls=cls)
#4. Insert intermediate table data
stu.cour.add(*courseList)
return True
修改为：
......
class Clazz(models.Model):
cno = models.AutoField(primary_key=True)
cname = models.CharField(max_length=30)
def __str__(self):
return u'Clazz:%s'%self.cname
class Course(models.Model):
course_no = models.AutoField(primary_key=True)
course_name = models.CharField(max_length=30)
def __str__(self):
return u'Course:%s'%self.course_name
class CustomManager(Manager):
#Returns a class object
def getClsObj(self,cname):
try:
cls = Clazz.objects.get(cname=cname)
except Clazz.DoesNotExist:
cls = Clazz.objects.create(cname=cname)
return cls
def getCourseList(self,*coursenames):
cList = []
for cn in coursenames:
try:
cour = Course.objects.get(course_name=cn)
except Course.DoesNotExist:
cour = Course.objects.create(course_name=cn)
cList.append(cour)
return cList
def create(self, **kwargs):
clazz = kwargs.get('cls','')
#Class information multi storage operation
clas = self.getClsObj(clazz)
#Replace string with object
#Student.objects.create(sname='',cls=clas)
kwargs['cls'] = clas
#Assign a separate value pair of course keys to course
course = kwargs.pop('cour')
#Storage operation of student information
stu = Manager.create(self,**kwargs)
#Total of the course information in storage
courseList = self.getCourseList(*course)
#The middle table of student course is stored in the database. An object or tuple can be unpacked automatically here
stu.cour.add(*courseList)
class Student(models.Model):
sno = models.AutoField(primary_key=True)
sname = models.CharField(max_length=30)
cls = models.ForeignKey(Clazz,on_delete=models.CASCADE)
cour = models.ManyToManyField(Course)
objects = CustomManager()
def __str__(self):
return u'Student:%s'%self.sname
# Get class object according to class name
def getCls(cname):
try:
cls = Clazz.objects.get(cname=cname)
except Clazz.DoesNotExist:
cls = Clazz.objects.create(cname=cname)
return cls
def getCourseList(*coursenames):
courseList = []
for cn in coursenames:
try:
c = Course.objects.get(course_name=cn)
except Course.DoesNotExist:
c = Course.objects.create(course_name=cn)
courseList.append(c)
return courseList
def registerStu(sname,cname,*coursenames):
#1. Get class objects
cls = getCls(cname)
#2. Gets the list of course objects
courseList = getCourseList(*coursenames)
#3. Insert student table data
try:
stu = Student.objects.get(sname=sname)
except Student.DoesNotExist:
stu = Student.objects.create(sname=sname,cls=cls)
#4. Insert intermediate table data
stu.cour.add(*courseList)
return True
（补充：这里以创建一次性完成多对多表数据的插入的 manage 管理器为例）
3.2 进入相应的 Django 环境
(django_env) [root@python mysite]# python3
>>> import os,django
>>> os.environ.setdefault("DJANGO_SETTINGS_MODULE", "mysite.settings")
'mysite.settings'
>>> django.setup()
>>> from user.models import *
3.3 一次性完成多对多表数据的插入
>>> Student.objects.create(sname='lili',cls='Class4',cour=('CSS','JS'))
（
补充：这里
1) 第一步执行：objects = CustomManager()
2) 第二步执行：def create(self, **kwargs)
3) 第三步执行：clazz = kwargs.get(‘cls’,”)，这步的结果是 clazz = ‘Class4’
4) 第四步执行：clas = self.getClsObj(clazz)，这步的结果是如果 Class4 在数据库中不存在则插入此条数据，并让 clas = cls
5) 第五步执行：cours = kwargs.pop(‘cour’)，这步的结果是 cours = (‘CSS’,’JS’)
6) 第六步执行：stu = Manager.create(self, **kwargs)，这步的结果是 stu = Student.objects.create(sname=”,cls=clas)
7) 第七步执行：courseList = self.getCourseList(*course)，这步的结果是如果 course 元组里的元素不存在则在数据库里创建，并将所有 course 里的元素放在 courseList 空列表中
8) 第八步执行：stu.cour.add(*courseList)，这步的结果是将 courseList 里的元素插入 Student 类的 cour 字段对应的中间表里
）
