ORM表关系及操作

Django使用django.db.models.ForeignKey`定义多对一关系。

class Employee(models.Model):
    emp_name = models.CharField(max_length=20,verbose_name="姓名")
    job = models.CharField(max_length=20,verbose_name="职位")
    salary = models.IntegerField(verbose_name="工资")
    department = models.ForeignKey(to=Department,on_delete=models.CASCADE,verbose_name="部门")

增
    def post(self,request):
        name = request.POST.get('dep_name')
        desc = request.POST.get('desc')
        try:
            Department.objects.create(dep_name=name,desc=desc)
        except Exception as e:
            print(e)
            return HttpResponse("添加失败")
        return redirect('/index/')
 删
 class DelView(View):
    def get(self,request,id):
        Employee.objects.filter(id=id).delete()
        return redirect('/index/')
改
class UpdateView(View):
    def get(self,request,id):
        emp_date=Employee.objects.get(id=id)
        return render(request,'update.html',{'emp':emp_date})
    def post(self,request,id):
        name = request.POST.get('emp_name')
        job = request.POST.get('job')
        salary = request.POST.get('salary')
        department = request.POST.get('department')
        try:
            Employee.objects.filter(id=id).update(
                emp_name=name,
                job=job,
                salary=salary,
                department=department,
            )
        except Exception as e:
            print(e)
            return HttpResponse("修改失败")
        return redirect('/index/')

# 查询id为2的学生的老师姓名
	--找到id为2的学生
    stu = Student.objects.get(id=2)
    --找到stu对应的老师    stu.teacher.name
    stu.外键.name

反向查询:通过django的内置属性来进行查询  模型类(模型类小写)_set()可以反向查询老师名下的所有学生,
    # 查询id为1的老师的所有学生    --先找到id为1的老师    
    tea = Teacher.objects.get(id=1)    
    --查询tea老师名下的所有学生  老师对象.模型类_set.all()    
    tea.student_set.all()