django获取指定列的数据

django获取指定列的数据

model一般都是有多个属性的，但是很多时候我们又只需要查询特定的某一个，这个时候可以用到values和values_list

[values()](https://docs.djangoproject.com/en/1.9/ref/models/querysets/#values)
values()¶

values(*fields)¶
Returns a QuerySet that returns dictionaries, rather than model instances, when used as an iterable.

Each of those dictionaries represents an object, with the keys corresponding to the attribute names of model objects.

[values_list()](https://docs.djangoproject.com/en/1.9/ref/models/querysets/#values-list)
values_list()¶

values_list(*fields, flat=False)¶
This is similar to values() except that instead of returning dictionaries, it returns tuples when iterated over. Each tuple contains the value from the respective field passed into the values_list() call — so the first item is the first field, etc.

看下面的代码：

利用values查询

from attendence.models import Employee
from attendence.models import EmployeeIP

#获取一个字段
ipList = EmployeeIP.objects.values("IP").first()
print(type(ipList))
# <class 'dict'>
print(ipList)
# {'IP': '192.168.1.41'}

#获取多个字段
empList = Employee.objects.values("first_name", "last_name", "email")[0:2]
print(type(empList))
# <class 'django.db.models.query.QuerySet'>
print(empList)
# [
#   {'last_name': 'Wei', 'first_name': 'Vena', 'email': 'Vena@test.com'},
#   {'last_name': 'Wan', 'first_name': 'Mark', 'email': 'mwan@test.com'}
# ]

利用values_list查询

ipList = EmployeeIP.objects.values_list("IP").first()
print(type(ipList))
# <class 'tuple'>
print(ipList)
# ('192.168.1.111',)

ipList = EmployeeIP.objects.values_list("IP")[0:2]
print(type(ipList))
# <class 'django.db.models.query.QuerySet'>
print(ipList)
# [('192.168.1.41',), ('192.168.1.44',)]
print(type(ipList[0]))
# <class 'tuple' >
print(ipList[0])
# 192.168.1.111

values和values_list的差别

从上面的代码中我们可以看到返回结果类型上细微的差别

• vlaues -
  • 单条记录 - <class 'dict'>
  • 多条记录 - <class 'django.db.models.query.QuerySet'>
• vlaues_list -
  • 单条记录 - <class 'tuple'>
  • 多条记录 - <class 'django.db.models.query.QuerySet'>