Django-18-多对多

模型

# 课程表 和 教师表 n:n
class Course(models.Model):
    course_id=models.AutoField(primary_key=True)
    course_name=models.CharField(max_length=30,unique=True)

    class Meta:
        db_table='t_course'

    def __unicode__(self):
        return u'Course:%s'%self.course_name

class Teacher(models.Model):
    tid = models.AutoField(primary_key=True)
    tname = models.CharField(max_length=30,unique=True)
    course = models.ManyToManyField(Course)

    class Meta:
        db_table='t_teacher'

    def __unicode__(self):
        return u'Teacher:%s--%s'%(self.tname,self.course)

迁移时会创建一张关联表

插入数据

from stu.models import *
cou1 = Course(course_name='Java')
cou2 = Course(course_name='Python')
cou1.save()
cou2.save()
t1 = Teacher(tname='张老师')
t1.save()
t2 = Teacher(tname='王老师')
t2.save()
t3 = Teacher(tname='李老师')
t3.save()
t1.course.add(cou1)
t1.course.add(cou2)
t2.course.add(cou1, cou2)

查询

Course.objects.first().teacher_set.all()
Teacher.objects.first().course.all()

封装函数插入数据

def insertData(tname,*coursenames):
    cour_name=[]
    
    for c in coursenames:
        try:
            cour = Course.objects.get(course_name=c)
        except Course.DoesNotExist:
            cour = Course.objects.create(course_name=c)
        cour_name.append(cour)
    t = Teacher(tname=tname)
    t.save()
    t.course.add(*cour_name)

insertData('wanglaoshi','语文','数学')