老师信息管理

思考

三种方式创建多对多外键方式及其优缺点。

通过外键创建

class Class(models.Model):    id = models.AutoField(primary_key=True)  # 主键    cname = models.CharField(max_length=32)  # 班级名称    first_day = models.DateField()  # 开班时间class Teacher(models.Model):    tname = models.CharField(max_length=32)# 自定义第三张表，通过外键关联上面两张表class Teacher2Class(models.Model):    teacher = models.ForeignKey(to="Teacher")    the_class = models.ForeignKey(to="Class")    class Meta:        unique_together = ("teacher", "the_class")

通过ManyToManyField创建

class Class(models.Model):    id = models.AutoField(primary_key=True)  # 主键    cname = models.CharField(max_length=32)  # 班级名称    first_day = models.DateField()  # 开班时间class Teacher(models.Model):    tname = models.CharField(max_length=32)    # 通过ManyToManyField自动创建第三张表    cid = models.ManyToManyField(to="Class", related_name="teachers")

通过外键和ManyToManyField创建

class Class(models.Model):    id = models.AutoField(primary_key=True)  # 主键    cname = models.CharField(max_length=32)  # 班级名称    first_day = models.DateField()  # 开班时间class Teacher(models.Model):    tname = models.CharField(max_length=32)    # 通过ManyToManyField和手动创建第三张表    cid = models.ManyToManyField(to="Class", through="Teacher2Class", through_fields=("teacher", "the_class"))class Teacher2Class(models.Model):    teacher = models.ForeignKey(to="Teacher")    the_class = models.ForeignKey(to="Class")    class Meta:        unique_together = ("teacher", "the_class")

表结构设计

class Teacher(models.Model):    tname = models.CharField(max_length=32)    cid = models.ManyToManyField(to="Class", related_name="teachers")

老师信息列表

URL部分

url(r'^teacher_list/$', app01_views.teacher_list, name="teacher_list"),

视图部分

def teacher_list(request):    teacher_list = models.Teacher.objects.all()    return render(request, "teacher_list.html", {"teacher_list": teacher_list})

前端部分

  
       
       
       添加新老师
     
         {% for teacher in teacher_list %}    
  {% endfor %}  
        
         
            
#
            
id
            
老师姓名
            
授课班级
            
操作
         
        
        
       
              
{
   { forloop.counter }}
              
{
   { teacher.id }}
              
{
   { teacher.tname }}
              
        {% for class in teacher.cid.all %}          {% if forloop.last %}            {
   { class.cname }}          {% else %}            {
   { class.cname }},          {% endif %}        {% endfor %}      
              
        删除        编辑      
           
      
     

删除老师信息

URL部分

url(r'^delete_teacher/(?P
     
      \d+)$', app01_views.delete_teacher, name="delete_teacher"),
     

视图部分

def delete_teacher(request, tid):    models.Teacher.objects.filter(id=tid).delete()    return redirect(reverse("teacher_list"))

前端部分

在老师列表页面添加一个删除的链接。

删除

添加老师信息

URL部分 

url(r'^add_teacher/$', app01_views.add_teacher, name="add_teacher"),

视图部分

def add_teacher(request):    if request.method == "POST":        tname = request.POST.get("tname")        class_ids = request.POST.getlist("class_id")        new_teacher = models.Teacher.objects.create(tname=tname)        # 查询出所有被选中的班级信息        class_objs = models.Class.objects.filter(id__in=class_ids)        # 将老师的授课班级设置为选中的班级， 以下四种都可以，注意什么时候加*        new_teacher.cid.set(class_objs)        # new_teacher.cid.add(*class_objs)        # new_teacher.cid.add(*class_ids)        # new_teacher.cid.set(class_ids)        new_teacher.save()        return redirect(reverse("teacher_list"))    class_list = models.Class.objects.all()    return render(request, "add_teacher.html", {"class_list": class_list})

前端部分

  
       
       
       
     
        {% csrf_token %}  
      
老师姓名：
  
      授课班级：    
            {% for class in class_list %}        {
   { class.cname }}      {% endfor %}        
      
     

编辑老师信息

URL部分

url(r'^edit_teacher/(?P
     
      \d+)$', app01_views.edit_teacher, name="edit_teacher"),
     

视图部分

def edit_teacher(request, tid):    teacher_obj = models.Teacher.objects.get(id=tid)    class_list = models.Class.objects.all()    if request.method == "POST":        tname = request.POST.get("tname")        class_ids = request.POST.getlist("class_id")        # 更新老师相关信息        teacher_obj.tname = tname        teacher_obj.cid.set(class_ids)        teacher_obj.save()  # 一定记得更新完要保存        return redirect(reverse("teacher_list"))    return render(request, "edit_teacher.html", {"class_list": class_list, "teacher": teacher_obj})

前端部分

  
       
       
       
     
        {% csrf_token %}  
      
老师姓名：
  
      授课班级：  
          {% for class in class_list %}      {% if class in teacher.cid.all %}        {
   { class.cname }}      {% else %}        {
   { class.cname }}      {% endif %}    {% endfor %}    
      
     

多对多操作

正向查询（由老师表查询班级表）

>>> teacher_obj = models.Teacher.objects.first()>>> teacher_obj.cid.all()  # 查询该老师授课的所有班级
     
      , 
      
       ]>
      
     

反向查询（由班级表反向查询老师表）

>>> class_obj = models.Class.objects.first()>>> class_obj.teachers.all()  # 此处用到的是related_name，如果不设置的话就用默认的表名_set
     
      , 
      
       , 
       
        ]>