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/$', app01_views.teacher_list, name="teacher_list"),
视图部分
def teacher_list(request):
teacher_list = models.Teacher.objects.all()
return render(request, "teacher_list.html", {"teacher_list": teacher_list})
前端部分
<!DOCTYPE html>
<html lang="zh-CN">
<head>
<meta charset="UTF-8">
<meta http-equiv="x-ua-compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>老师信息页面</title>
</head>
<body>
<a href="{% url 'add_teacher' %}">添加新老师</a>
<table border="1">
<thead>
<tr>
<th>#</th>
<th>id</th>
<th>老师姓名</th>
<th>授课班级</th>
<th>操作</th>
</tr>
</thead>
<tbody>
{% for teacher in teacher_list %}
<tr>
<td>{{ forloop.counter }}</td>
<td>{{ teacher.id }}</td>
<td>{{ teacher.tname }}</td>
<td>
{% for class in teacher.cid.all %}
{% if forloop.last %}
{{ class.cname }}
{% else %}
{{ class.cname }},
{% endif %}
{% endfor %}
</td>
<td>
<a href="{% url 'delete_teacher' teacher.id %}">删除</a>
<a href="{% url 'edit_teacher' teacher.id %}">编辑</a>
</td>
</tr>
{% endfor %}
</tbody>
</table>
</body>
</html>
删除老师信息
URL部分
url(r'^delete_teacher/(?P<tid>\d+)$', 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。
<a href="{% url 'delete_teacher' teacher.id %}">删除</a>
添加老师信息
URL部分
url(r'^add_teacher/$', app01_views.add_teacher, name="add_teacher"),
视图部分
def add_teacher(request):
if request.method == "POST":
tname = request.POST.get("tname")
class_ids = request.POST.getlist("class_id")
new_teacher = models.Teacher.objects.create(tname=tname)
# 查询出所有被选中的班级信息
class_objs = models.Class.objects.filter(id__in=class_ids)
# 将老师的授课班级设置为选中的班级， 以下四种都可以，注意什么时候加*
new_teacher.cid.set(class_objs)
# new_teacher.cid.add(*class_objs)
# new_teacher.cid.add(*class_ids)
# new_teacher.cid.set(class_ids)
new_teacher.save()
return redirect(reverse("teacher_list"))
class_list = models.Class.objects.all()
return render(request, "add_teacher.html", {"class_list": class_list})
前端部分
<!DOCTYPE html>
<html lang="zh-CN">
<head>
<meta charset="UTF-8">
<meta http-equiv="x-ua-compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>添加老师</title>
</head>
<body>
<form action="{% url 'add_teacher' %}" method="post">
{% csrf_token %}
<p>老师姓名：<input type="text" name="tname"></p>
<label for="class_id">授课班级：</label>
<select name="class_id" id="class_id" multiple>
{% for class in class_list %}
<option value="{{ class.id }}">{{ class.cname }}</option>
{% endfor %}
</select>
<p><input type="submit" value="提交"></p>
</form>
</body>
</html>
编辑老师信息
URL部分
url(r'^edit_teacher/(?P<tid>\d+)$', 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
<!DOCTYPE html>
<html lang="zh-CN">
<head>
<meta charset="UTF-8">
<meta http-equiv="x-ua-compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>编辑老师信息</title>
</head>
<body>
<form action="{% url 'edit_teacher' teacher.id %}" method="post">
{% csrf_token %}
<p>老师姓名：<input type="text" name="tname" value="{{ teacher.tname }}"></p>
<label for="class_id">授课班级：</label>
<select name="class_id" id="class_id" multiple>
{% for class in class_list %}
{% if class in teacher.cid.all %}
<option value="{{ class.id }}" selected>{{ class.cname }}</option>
{% else %}
<option value="{{ class.id }}">{{ class.cname }}</option>
{% endif %}
{% endfor %}
</select>
<p><input type="submit" value="提交"></p>
</form>
</body>
</html>
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 <QuerySet [<Class: Class object>, <Class: Class object>]>
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 <QuerySet [<Teacher: Teacher object>, <Teacher: Teacher object>, <Teacher: Teacher object>]>