ORM版學員管理系統 3

時間  2019-11-13
標籤 orm 學員 管理 系統 欄目 Java 简体版
原文   原文鏈接

老師信息管理

思考

三種方式建立多對多外鍵方式及其優缺點。html

經過外鍵建立

複製代碼 
class Class(models.Model):
    id = models.AutoField(primary_key=True)  # 主鍵
    cname = models.CharField(max_length=32)  # 班級名稱
    first_day = models.DateField()  # 開班時間


class Teacher(models.Model):
    tname = models.CharField(max_length=32)


# 自定義第三張表，經過外鍵關聯上面兩張表
class Teacher2Class(models.Model):
    teacher = models.ForeignKey(to="Teacher")
    the_class = models.ForeignKey(to="Class")

    class Meta:
        unique_together = ("teacher", "the_class")
複製代碼

經過ManyToManyField建立

複製代碼 
class Class(models.Model):
    id = models.AutoField(primary_key=True)  # 主鍵
    cname = models.CharField(max_length=32)  # 班級名稱
    first_day = models.DateField()  # 開班時間


class Teacher(models.Model):
    tname = models.CharField(max_length=32)
    # 經過ManyToManyField自動建立第三張表
    cid = models.ManyToManyField(to="Class", related_name="teachers")
複製代碼

經過外鍵和ManyToManyField建立

複製代碼 
class Class(models.Model):
    id = models.AutoField(primary_key=True)  # 主鍵
    cname = models.CharField(max_length=32)  # 班級名稱
    first_day = models.DateField()  # 開班時間


class Teacher(models.Model):
    tname = models.CharField(max_length=32)
    # 經過ManyToManyField和手動建立第三張表
    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")
複製代碼

表結構設計

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

老師信息列表

URL部分

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

視圖部分

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

前端部分

複製代碼 
<!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>老師信息頁面</title>
</head>
<body>
<a href="{% url 'add_teacher' %}">添加新老師</a>
<table border="1">
  <thead>
  <tr>
    <th>#</th>
    <th>id</th>
    <th>老師姓名</th>
    <th>授課班級</th>
    <th>操做</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 %}">刪除</a>
        <a href="{% url 'edit_teacher' teacher.id %}">編輯</a>
      </td>
    </tr>
  {% endfor %}
  </tbody>
</table>
</body>
</html>
複製代碼

刪除老師信息

URL部分

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

視圖部分

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

前端部分

在老師列表頁面添加一個刪除的連接。前端

<a href="{% url 'delete_teacher' teacher.id %}">刪除</a>

添加老師信息

URL部分 

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

視圖部分

複製代碼 
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)
        # 查詢出全部被選中的班級信息
        class_objs = models.Class.objects.filter(id__in=class_ids)
        # 將老師的授課班級設置爲選中的班級， 如下四種均可以，注意何時加*
        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})
複製代碼

前端部分

複製代碼 
<!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>添加老師</title>
</head>
<body>
<form action="{% url 'add_teacher' %}" method="post">
  {% csrf_token %}
  <p>老師姓名：<input type="text" name="tname"></p>
  <label for="class_id">授課班級：</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>
複製代碼

編輯老師信息

URL部分

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

視圖部分

複製代碼 
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")
        # 更新老師相關信息
        teacher_obj.tname = tname
        teacher_obj.cid.set(class_ids)
        teacher_obj.save()  # 必定記得更新完要保存
        return redirect(reverse("teacher_list"))

    return render(request, "edit_teacher.html", {"class_list": class_list, "teacher": teacher_obj})
複製代碼

前端部分

複製代碼 
<!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>編輯老師信息</title>
</head>
<body>
<form action="{% url 'edit_teacher' teacher.id %}" method="post">
  {% csrf_token %}
  <p>老師姓名：<input type="text" name="tname" value="{{ teacher.tname }}"></p>
  <label for="class_id">授課班級：</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>
複製代碼

多對多操做

正向查詢（由老師表查詢班級表）app

>>> teacher_obj = models.Teacher.objects.first()
>>> teacher_obj.cid.all()  # 查詢該老師授課的全部班級
<QuerySet [<Class: Class object>, <Class: Class object>]>

反向查詢（由班級表反向查詢老師表）oop

>>> class_obj = models.Class.objects.first()
>>> class_obj.teachers.all()  # 此處用到的是related_name，若是不設置的話就用默認的表名_set
<QuerySet [<Teacher: Teacher object>, <Teacher: Teacher object>, <Teacher: Teacher object>]> 
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