使用ORM进行前后端数据交互

使用ORM进行数据交互 

前期准备

必备知识：ORM操作，数据库多表操作、Django部分知识。

三张表：班级、老师、学生

一对多关系：班级与学生

多对多关系：班级与老师

#创建班级表
class Classes(models.Model):
    title = models.CharField(max_length=32)
    n=models.ManyToManyField('Teachers')


#创建老师表
class Teachers(models.Model):
    name= models.CharField(max_length=32)
    age=models.IntegerField(default=30)
    gender=models.BooleanField(default=False)
    is_married=models.BooleanField(default=True)
    address = models.CharField(max_length=50,default='xiaogan')


#创建学生表
class Student(models.Model):
    username=models.CharField(max_length=32)
    age=models.IntegerField()
    #只能写true和false
    gender=models.BooleanField()
    cs=models.ForeignKey(Classes,on_delete=models.DO_NOTHING)
    address=models.CharField(max_length=50,default='xiaogan')

目标

1.对学生，班级的增删改查

2.为班级分配老师

　　

URL路由

from django.contrib import admin
from django.urls import path
from app01.views import *

urlpatterns = [
    path('admin/', admin.site.urls),
    path('classes.html/',get_classes),
    path('addclasses.html/',add_classes),
    path('delclasses.html/',del_classes),
    path('altclasses.html/',alt_classes),
    path('student.html/', get_student),
    path('addstudent.html/',add_student),
    path('delstudent.html/',del_student),
    path('altstudent.html/', alt_student),
    path('choose_teacher.html/', choose_teacher),
    path("ajax_get_date.html/", ajax_get_data),
]

创建表

from django.db import models


# 一对多：班级与学生
# 多对多：班级与老师

# Create your models here.
#创建班级表
class Classes(models.Model):
    title = models.CharField(max_length=32)
    n=models.ManyToManyField('Teachers')


#创建老师表
class Teachers(models.Model):
    name= models.CharField(max_length=32)
    age=models.IntegerField(default=30)
    gender=models.BooleanField(default=False)
    is_married=models.BooleanField(default=True)
    address = models.CharField(max_length=50,default='xiaogan')


#创建学生表
class Student(models.Model):
    username=models.CharField(max_length=32)
    age=models.IntegerField()
    #只能写true和false
    gender=models.BooleanField()
    cs=models.ForeignKey(Classes,on_delete=models.DO_NOTHING)
    address=models.CharField(max_length=50,default='xiaogan')

视图函数

from django.shortcuts import render,HttpResponse,redirect
from app01 import models
# Create your views here.

def get_classes(request):
    cls_list=models.Classes.objects.all()
    print(cls_list)
    # return HttpResponse('ok')
    return render(request,"get_classes.html",{'cls_list':cls_list})

def add_classes(request):
    if request.method=='GET':
        return render(request,'add_classes.html')
    elif request.method=="POST":
        title=request.POST.get('title')
        print(title)

        # ret=models.Classes.objects.all().values('title')
        # for Title in ret:
        #     if Title['title']==title:
        #         print(Title)
        models.Classes.objects.create(title=title)
        #注意这里是url路径
        return redirect('/classes.html')


def del_classes(request):
    nid=request.GET.get('nid')
    print(nid)
    ret=models.Classes.objects.filter(id=nid).delete()
    print(ret)
    return redirect('/classes.html/')

def alt_classes(request):
    if request.method=="GET":
        nid = request.GET.get('nid')
        obj=models.Classes.objects.filter(id=nid)[0]
        return render(request,'alt_classes.html',{'obj':obj})
    elif request.method=="POST":
        nid=request.GET.get("nid")
        title=request.POST.get("title")
        models.Classes.objects.filter(id=nid).update(title=title)
        return redirect("/classes.html/")


def get_student(request):
    stu_list = models.Student.objects.all()
    print(stu_list)
    # return HttpResponse('ok')
    return render(request, "get_student.html", {'stu_list': stu_list})
def add_student(request):
    if request.method=='GET':
        cs_list=models.Classes.objects.all()
        print(cs_list)
        return render(request,'add_student.html',{'cs_list':cs_list})
    elif request.method=="POST":
        name=request.POST.get('name')
        age=request.POST.get('age')
        gender=request.POST.get('gender')
        cs_id=request.POST.get('class')
        address=request.POST.get('address')
        print(name,age,gender,cs_id,address)
        # ret=models.Classes.objects.all().values('title')
        # for Title in ret:
        #     if Title['title']==title:
        #         print(Title)
        models.Student.objects.create(username=name,age=age,gender=gender,cs_id=cs_id,address=address)
        #注意这里是url路径
        return redirect('/student.html')

def del_student(request):
    nid = request.GET.get('nid')
    print(nid)
    ret = models.Student.objects.filter(id=nid).delete()
    print(ret)
    return redirect('/student.html/')
def alt_student(request):
    if request.method=="GET":
        nid = request.GET.get('nid')
        obj=models.Student.objects.filter(id=nid)[0]
        cs_list = models.Classes.objects.all()
        return render(request,'alt_student.html',locals())

    elif request.method=="POST":
        nid=request.GET.get("nid")
        name = request.POST.get('name')
        age = request.POST.get('age')
        gender = request.POST.get('gender')
        cs_id = request.POST.get('class')
        address = request.POST.get('address')
        print(name, age, gender, cs_id, address)
        models.Student.objects.filter(id=nid).update(username=name,age=age,gender=gender,cs_id=cs_id,address=address)
        return redirect("/student.html/")
def choose_teacher(request):

    if request.method=="GET":
        nid=request.GET.get('nid')
        print(nid)
        #多对多的字段创建的Class表，我们可以通过id，拿到这个班级对象
        #
        cls=models.Classes.objects.filter(id=nid).first()
        #当前班级的老师列表
        cls_teacher=cls.n.all()

        #所有老师的列表
        teacher_list=models.Teachers.objects.all()

        teachers=[]
    #如果teacher在cls_list中，说明，这个老师已经是这个班级的任课老师
        for teacher in teacher_list:
            if teacher  in cls_teacher:continue
            else:teachers.append(teacher)

        return render(request,"set_teacher.html",{'teachers':teachers,'cls_teacher':cls_teacher,'nid':nid})
    elif request.method=="POST":
        #获取现在操作的班级id
        nid=request.GET.get("nid")
        #获取现在所选老师 id
        teacher_id=request.POST.get('teacher_id')
        print(nid,teacher_id)
        Class=models.Classes.objects.filter(id=nid).first()
        Class.n.add(2)
        # return render(request, "get_classes", {'nid': nid})
        return redirect("/classes.html/")

HTML代码

班级首页

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>

<div>
    <table border="1">
        <thead>
            <tr>
                <th>ID</th>
                <th>名称</th>
                <th>操作</th>
            </tr>
         </thead>
        <tbody>
            {% for row in cls_list %}
                <tr>
                    <td>
                         {{ row.id }}
                    </td>
                    <td>
                        {{ row.title }}
                     </td>
                    <td>
                        <a href="/delclasses.html?nid={{ row.id }}">删除</a>

                        <a href="/altclasses.html?nid={{ row.id }}">编辑</a>

                        <a href="/choose_teacher.html?nid={{ row.id }}">分配老师</a>
                    </td>
                </tr>
            {%  endfor %}
                <tr>
                    <td>

                    </td>
                    <td>
                            <a href="/addclasses.html/">添加</a>
                    </td>
                </tr>
         </tbody>
</table>
</div>

</body>
</html>

编辑班级名称代码

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<form action="/altclasses.html/?nid={{ obj.id }}" method="post">
    {% csrf_token %}
<p><input type="text" name="title" value="{{ obj.title  }}"></p>
<!--<p><input type="text" name="id" value="{{ obj.id }}"></p>-->
<input type="submit">
</form>
</body>
</html>

添加班级代码

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<form action="/addclasses.html/" method="post">
    {% csrf_token %}
<p>班级：<input type="text" name="title"></p>
<p><input type="submit"></p>
</form>
</body>
</html>

为班级分配任课老师

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
    <p>班级现在的任课老师：
    {% for teacher in cls_teacher %}
    <p>{{ teacher.name }}</p>
     {% endfor %}
    </p>
    添加新的任课老师：<br>
<form action="/choose_teacher.html/?nid={{ nid }}" method="post">
    {% csrf_token %}
     <select multiple size=10  name="teacher_id">
        {% for item in teachers %}
        <option value="{{ item.id }}">{{ item.id }} {{ item.name }}</option>
         {% endfor %}
    </select>
    <!--  {{ item.name }}-->
    <br>
    <input type="submit">
</form>
</body>
</html>

学生首页

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>

<div>
    <table border="1">
        <thead>
            <tr>
                <th>ID</th>
                <th>姓名</th>
                <th>年龄</th>
                <th>性别</th>
                <th>班级</th>
                <th>住址</th>
                <th>行为</th>
            </tr>
         </thead>
        <tbody>
            {% for row in stu_list %}
                <tr>
                    <td>
                         {{ row.id }}
                    </td>
                    <td>
                        {{ row.username }}
                     </td>
                    <td>
                        {{ row.age }}
                     </td>
                    <td>
                        {{ row.gender }}
                     </td>
                    <td>
                        {{ row.cs.title }}
                     </td>
                     <td>
                        {{ row.address }}
                     </td>
                    <td>
                        <a href="/delstudent.html?nid={{ row.id }}">删除</a>

                        <a href="/altstudent.html?nid={{ row.id }}">编辑</a>
                    </td>
                </tr>
            {%  endfor %}
                <tr>
                    <td>

                    </td>
                    <td>
                            <a href="/addstudent.html/">添加</a>
                    </td>
                </tr>
         </tbody>
</table>
</div>

</body>
</html>

 

添加学生代码

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<form action="/addstudent.html/" method="post">
    {% csrf_token %}
<p>学生姓名：<input type="text" name="name"></p>
<p>学生年龄：<input type="text" name="age"></p>
<p>性别：男<input type="radio" name="gender" value='1'> 女<input type="radio"  name="gender" value='0' > </p>
<select name="class">
    {% for row in cs_list %}
    {{ row.id }}
    班级：<option value="{{ row.id }}">{{ row.title }}</option>
    {% endfor %}
</select>
<p>住址：<input type="text" name="address"></p>
<p><input type="submit"></p>
</form>
</body>
</html>

编辑学生代码

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<form action="/altstudent.html/?nid={{ obj.id }}" method="post">
    {% csrf_token %}
<p>学生姓名：<input type="text" name="name"></p>
<p>学生年龄：<input type="text" name="age"></p>
<p>性别：男<input type="radio" name="gender" value='1'> 女<input type="radio"  name="gender" value='0' > </p>
<select name="class">
    {% for row in cs_list %}
    {{ row.id }}
    班级：<option value="{{ row.id }}">{{ row.title }}</option>
    {% endfor %}
</select>
<p>住址：<input type="text" name="address"></p>
<p><input type="submit"></p>
<input type="submit">
</form>
</body>
</html>

注意：删除对应相应的视图函数处理

分析与总结

ORM：

具体看前几篇文章。

视图函数：

1.每次的请求可能有get数据，也有post发送过来的数据，如果处理方式不同，做相应的处理。

2.redirect(url)：跳转到哪个页面下，这里面的url对应url里面的路径。

 HTML：

1.

通过form表单向服务端发送数据。

客户端发送的是键值对,服务端接收到的也是键值对。

所以表单标签一定要使用name指定键名，text，password的值为用户输入，radio,select的值为用户选择，所以一定要设置对应每个选项的value值。

注意：比如男，女这种选项，value设置为"1","0",服务端存储到数据中会进行处理，转换为True，Flase。

2.通过id对应数据库表里的记录，而这个id通过get方式发送给服务端。