一对多需要使用外键
一：外键创建ForeignKey
b=models.ForeignKey(to="Business",to_field=("id"))#django会在生成表的时候变为b_id
to表示和那个表关联，to_field没有和那个字段关联，不写默认是id
from django.db import models # Create your models here. class Foo(models.Model): name=models.CharField(max_length=32) class Business(models.Model): caption=models.CharField(max_length=32) code=models.CharField(max_length=32,null=True,default="SA") fk=models.ForeignKey(to="Foo",to_field=("id"))#默认会和主键关联 class Host(models.Model): nid=models.AutoField(primary_key=True) hostname=models.CharField(max_length=32,db_index=True) ip=models.GenericIPAddressField(protocol='ipv4',db_index=True) port=models.IntegerField() b=models.ForeignKey(to="Business",to_field=("id"))
二：一对多数据创建
一对多数据创建有两种方式
1)使用对象创建
Host.objects.create( hostname="host1", ip="1.1.1.1", port="22", b=Business.objects.filter(id=1).first(),)
2）直接使用外建字段_id创建
Host.objects.create( hostname="host1", ip="1.1.1.1", port="22", b_id=1,) #外键创建时候会自动把字段b建立成b_id字段，可以直接赋值。这种方法好于第一种，原因不需要连表查询，推荐第二种
三：一对多数据查询
一对多数据查询有两种形式
1）queryset内容为对象
Host.objects.filter(nid__gt=0)
Host.objects.all()等
host_list=Host.objects.all() for row in host_list: print(row.b_id) #直接访问b_id print(row.b) #这个是Business对象，所以访问下面的字段 print(row.b.caption)
2)查询使用values和values_list指定字段，使用row.b.caption会直接报错。这里可以使用双下线跨表查询.
3)查询使用values_list指定字段，使用row.b.caption会直接报错。这里可以使用双下线跨表查询.
注：values返回是字典，values_list返回是元组
示例如下： views
def host1(request): v1=Host.objects.filter(nid__gt=0) #v1=Host.objects.filter(nid__gt=0) # v1=Host.objects.filter(nid__gt=0).values("nid","hostname","b_id","b.caption") #b.caption不能跨表直接报错 v2=Host.objects.filter(nid__gt=0).values("nid","hostname","b_id","b__caption") #两个下划线可以实现跨表 #filter(nid__gt=0).values("nid","hostname","b_id","b__caption")相跨表都用双下划线 #queryset对象内部为字典 for row in v2: print(row["nid"],row["hostname"],row["b_id"],row["b__caption"]) v3=Host.objects.filter(nid__gt=0).values_list("nid","hostname","b_id","b__caption") return render(request,"host.html",{"v1":v1,"v2":v2,"v3":v3})
模板代码：
<!DOCTYPE html> <html lang="en" xmlns="http://www.w3.org/1999/html"> <head> <meta charset="UTF-8"> <title>Title</title> <style> .shade { position: fixed; top: 0; right: 0; bottom: 0; left: 0; background-color: #333333; opacity: 0.6; z-index: 9; } .add-mode { position: fixed; height: 300px; 400px; top: 100px; left: 50%; margin-left: -200px; z-index: 11; background-color: white; } .hide { display: none; } </style> </head> <body> <input type="button" value="增加" id="add_host"> <h1>主机列表（对象）</h1> <table border="1px"> <thead> <tr> <th>序号</th> <th>主机名</th> <th>主机地址</th> <th>端口</th> <th>业务线名称</th> </tr> </thead> <tbody> {% for row in v1 %} <tr host-id="{{ row.nid }}" bid="{{ row.b_id }}"> <td>{{ forloop.revcounter }}</td> <td>{{ row.hostname }}</td> <td>{{ row.ip }}</td> <td>{{ row.port }}</td> <td>{{ row.b.caption }}</td> </tr> {% endfor %} </tbody> </table> <h1>主机列表（字典）</h1> <table border="1px"> <thead> <tr> <th>主机名</th> <th>主机地址</th> <th>端口</th> <th>业务线名称</th> </tr> </thead> <tbody> {% for row in v2 %} <tr host-id="{{ row.nid }}" bid="{{ row.b_id }}"> <td>{{ row.hostname }}</td> <td>{{ row.ip }}</td> <td>{{ row.port }}</td> <td>{{ row.b__caption }}</td> </tr> {% endfor %} </tbody> </table> <h1>主机列表（元组）</h1> <table border="1px"> <thead> <tr> <th>主机名</th> <th>主机地址</th> <th>端口</th> <th>业务线名称</th> </tr> </thead> <tbody> {% for row in v3 %} <tr host-id="{{ row.nid }}" bid="{{ row.b_id }}"> <td>{{ row.0 }}</td> <td>{{ row.1 }}</td> <td>{{ row.2 }}</td> <td>{{ row.3 }}</td> </tr> {% endfor %} </tbody> </table> <table border="1px"> <thead> <tr> <th>序号</th> <th>主机名</th> <th>主机地址</th> <th>端口</th> <th>业务线名称</th> </tr> </thead> <tbody> {% for i in v1 %} {% for row in v1 %} <tr host-id="{{ row.nid }}" bid="{{ row.b_id }}"> <td>{{ forloop.parentloop }}</td> <td>{{ row.hostname }}</td> <td>{{ row.ip }}</td> <td>{{ row.port }}</td> <td>{{ row.b.caption }}</td> </tr> {% endfor %} {% endfor %} </tbody> </table> <!--模态对话框实现增加主机信息--> <div class="shade hide"></div> <div class="add-mode hide"> <form action="/host" method="post"> <div class="group"> <input type="text" name="hostname" placeholder="请输入主机名"> </div> <div class="group"> <input type="text" name="ip" placeholder="请输入主机IP"> </div> <div class="group"> <input type="text" name="port" placeholder="请输入主机端口"> </div>
<!--绑定businss信息--> <div class="group"> <select name="group_id"> {% for group in v4 %} <option value="{{ group.id }}">{{ group.caption }}</option> {% endfor %} </select> </div> <div class="group"> <input type="submit" value="提交"> <input type="button" value="取消"> </div> </form> </div> <script src="/static/jquery-1.12.4.js"></script> <script> $("#add_host").click( function () { $(".shade,.add-mode").removeClass("hide") } ) </script> </body> </html>