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>]> 

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