django获取单表数据的三种方式
v1 = models.Business.objects.all()
# v1是QuerySet的列表 ,内部元素都是对象
v2 = models.Business.objects.all().values('id','caption') //这里不加all()也可以
# v2是QuerySet的列表 ,内部元素都是字典
v3 = models.Business.objects.all().values_list('id','caption') //这里不加all()也可以
# v3是QuerySet的列表 ,内部元素都是元组
def business(request):
v1 = models.Business.objects.all()
v2 = models.Business.objects.all().values('id','caption')
v3 = models.Business.objects.all().values_list('id','caption')
print(v1,v2,v3)
return render(request, 'business.html', {'v1': v1, 'v2': v2, 'v3': v3})
business.html
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title></title>
</head>
<body>
<h1>业务线列表(对象)</h1>
<ul>
{% for row in v1 %}
<li>{{ row.id }} - {{ row.caption }} - {{ row.code }}</li>
{% endfor %}
</ul>
<h1>业务线列表（字典）</h1>
<ul>
{% for row in v2 %}
<li>{{ row.id }} - {{ row.caption }}</li>
{% endfor %}
</ul>
<h1>业务线列表（元组）</h1>
<ul>
{% for row in v3 %}
<li>{{ row.0 }} - {{ row.1 }}</li>
{% endfor %}
</ul>
</body>
</html>
获取一个对象
方法一：如果存在就返回一个对象，如果不存在就报错,不推荐
models.Business.objects.get(id=1)
方法二：如果存在就返回一个对象，不存在就返回none，推荐
models.Business.objects.filter(id=1).first()
外键：
class Business(models.Model):
caption = models.CharField(max_length=32)
code = models.CharField(max_length=32,null=True,default='SA')
class Host(models.Model):
id = models.AutoField(primary_key=True)
hostname = models.CharField(max_length=32)
ip = models.GenericIPAddressField(protocol='ipv4')
port = models.IntegerField()
b = models.ForeignKey(to='Business',to_field='id')
v = models.Host.objects.filter(nid__gt=0)
v[0].b.caption ----> 通过点（.）进行跨表
实例：跨表查询的三种方式
def host(request):
host_obj = models.Host.objects.all()
host_obj2 = models.Host.objects.filter(b__caption='运维').values('id','hostname','ip','port','b__code')
for i in host_obj2:
print(i['id'],i['hostname'],i['ip'],i['port'],i['b__code'])
host_obj3 = models.Host.objects.filter(b__caption='运维').values_list('id', 'hostname', 'ip', 'port', 'b__code')
return render(request,'host.html',{'host_obj':host_obj,'host_obj2':host_obj2,'host_obj3':host_obj3})
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
</head>
<body>
<h2>对象</h2>
<table border="1px">
<thead>
<tr>
<th>ID</th>
<th>主机名</th>
<th>ip</th>
<th>port</th>
<th>业务线</th>
<th>业务线编码</th>
</tr>
</thead>
<tbody>
{% for i in host_obj %}
<tr hid="{{ i.id }}" bid="{{ i.b_id }}">
<td>{{ forloop.counter }}</td>
<td>{{ i.hostname }}</td>
<td>{{ i.ip }}</td>
<td>{{ i.port }}</td>
<td>{{ i.b.caption }}</td>
<td>{{ i.b.code }}</td>
</tr>
{% endfor %} </tbody>
</table>
<h2>字典</h2>
<table border="1px">
<thead>
<tr>
<th>ID</th>
<th>主机名</th>
<th>ip</th>
<th>port</th>
<th>业务线编码</th>
</tr>
</thead>
<tbody> {% for i in host_obj2 %}
<tr hid="{{ i.id }}" bid="{{ i.b_id }}">
<td>{{ forloop.counter }}</td>
<td>{{ i.hostname }}</td>
<td>{{ i.ip }}</td>
<td>{{ i.port }}</td> <td>{{ i.b__code }}</td>
</tr>
{% endfor %} </tbody>
</table>
<h2>元组</h2>
<table border="1px">
<thead>
<tr>
<th>ID</th>
<th>主机名</th>
<th>ip</th>
<th>port</th>
<th>业务线编码</th>
</tr>
</thead>
<tbody> {% for i in host_obj3 %}
<tr hid="{{ i.0 }}" bid="{{ i.b_id }}">
<td>{{ forloop.counter }}</td>
<td>{{ i.1 }}</td>
<td>{{ i.2 }}</td>
<td>{{ i.3 }}</td>
<td>{{ i.4 }}</td>
</tr>
{% endfor %} </tbody>
</table> </body>
</html>