63、ORM学员管理系统--Django框架之外键
学生信息管理
展示学生信息
URL部分
url(r'^student_list/', app01_views.student_list, name="student_list"),
视图部分
def student_list(request):
student_list = models.Student.objects.all()
return render(request, "student_list.html", {"student_list": student_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>学生列表</title>
</head>
<body>
<a href="{% url 'add_student' %}">添加学生</a>
<table border="1">
<thead>
<tr>
<th>#</th>
<th>id</th>
<th>学生姓名</th>
<th>学生班级</th>
<th>开班日期</th>
<th>操作</th>
</tr>
</thead>
<tbody>
{% for student in student_list%}
<tr>
<td>{{ forloop.counter}}</td>
<td>{{ student.id }}</td>
<td>{{ student.sname }}</td>
<td>{{ student.cid.cname }}</td>
<td>{{ student.cid.first_day|date:'Y-m-d' }}</td>
<td>
<a href="{% url 'delete_student' student.id %}">删除</a>
<a href="{% url 'edit_student' student.id %}">编辑</a>
</td>
</tr>
{% endfor %}
</tbody>
</table>
</body>
</html>
删除学生信息
URL部分
url(r'^delete_student/(?P<sid>\d+)$', app01_views.delete_student, name="delete_student"),
视图部分
def delete_student(request, sid):
models.Student.objects.filter(id=sid).delete()
return redirect(reverse("student_list"))
前端部分
<a href="{% url 'delete_student' student.id %}">删除</a>
添加学生信息
URL部分
url(r'^add_student/$', app01_views.add_student, name="add_student"),
视图部分
def add_student(request):
if request.method == "POST":
sname = request.POST.get("sname")
class_id = request.POST.get("class_id")
models.Student.objects.create(sname=sname, cid_id=class_id)
return redirect(reverse("student_list"))
class_list = models.Class.objects.all()
return render(request, "add_student.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>添加学生</title>
</head>
<body>
<form action="{% url 'add_student' %}" method="post">
{% csrf_token %}
<p>学生姓名：<input type="text" name="sname"></p>
<label for="class_id">所在班级：</label>
<select name="class_id" id="class_id">
{% 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>
编辑学生信息
URL部分
url(r'^edit_student/(?P<sid>\d+)$', app01_views.edit_student, name="edit_student"),
视图部分
def edit_student(request, sid):
# 获取到编辑的学生对象
student_obj = models.Student.objects.get(id=sid)
# 获取所有的班级数据
class_list = models.Class.objects.all()
if request.method == "POST":
sname = request.POST.get("sname")
class_id = request.POST.get("class_id")
student_obj.sname = sname
student_obj.cid_id = class_id
student_obj.save()
return redirect(reverse("student_list"))
return render(request, "edit_student.html", {"student": student_obj, "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>编辑学生信息</title>
</head>
<body>
<form action="{% url 'edit_student' student.id %}" method="post">
{% csrf_token %}
<p>学生姓名：<input type="text" name="sname" value="{{ student.sname }}"></p>
<label for="class_id">所在班级：</label>
<select name="class_id" id="class_id">
{% for class in class_list %}
{% if class.id == student.cid_id %}
<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>
基于对象的跨表查询
一对多查询（班级表和学生表）
正向查询（由学生表查询班级表）
查询学生的班级信息
>>> student_obj = models.Student.objects.first() >>> student_obj.cid # 通过model类中的属性查找到对应的外键数据对象 <Class: Class object> >>> student_obj.cid.cname '1班' >>> student_obj.cid_id # 获取实际外键的值 1
反向查询（由班级表查询学生表）
查询班级的学生信息
>>> class_obj = models.Class.objects.first() # 获取第一个班级对象 >>> class_obj.student_set.all() # 通过表名_set反向查询出所有的学生 <QuerySet [<Student: Student object>, <Student: Student object>]>
注意：
如果不在外键的字段中设置related_name的话，默认就用表名_set。
如果设置了related_name="students"，反向查询时可直接使用students进行反向查询。
>>> class_obj.students.all()
一对一查询
表结构设计
class Student(models.Model):
sname = models.CharField(max_length=32, verbose_name="学生姓名")
the_class = models.ForeignKey(to=Class, to_field="id", on_delete=models.CASCADE, related_name="students")
detail = models.OneToOneField(to="StudentDetail", null=True)
class StudentDetail(models.Model):
height = models.PositiveIntegerField()
weight = models.PositiveIntegerField()
email = models.EmailField()
正向查询（由学生信息表查询学生详情表）
>>> student_obj = models.Student.objects.first() >>> student_obj.detail.email '1@1.com'
反向查询（由学生详情表反向查询学生信息表）
>>> detail_obj = models.StudentDetail.objects.get(id=1) >>> detail_obj.student.sname 'a'
