[Python知识库]django自定义查询

自定义查询对象 - objects

1. 声明类EntryManager,继承自models.Manager

在EntryManager 中添加自定义函数

class EntryManager(models.Manager):
      # parameter自定义参数列表,
      def function_name(self,parameter)
          pass
      return ....

2. 使用 EntryManager 覆盖models 类中的objects

class Entry(models.Model):
      objects = EntryManager()

例如: 添加自定义函数 查询TestUser表中有多少个用户

完整代码:

index/models.py

from django.db import models


# 声明自定义的 objects -继承 models.Manager
class UserManager(models.Manager):
    # 添加自定义函数
    def user_count(self):
        return self.all().count()


# Create your models here.
class TestUser(models.Model):
    # 使用 UserManager 覆盖当前的objects
    objects = UserManager()
    name = models.CharField(max_length=150)
    age = models.IntegerField()
    email = models.EmailField(default=True)
    isActive = models.BooleanField(default=True)

index/views.py

from django.http import HttpResponse
from .models import *


# Create your views here
# 展示有多少个用户
def display_user(request):
    count = TestUser.objects.user_count()
    return HttpResponse(count)

index/urls.py

from django.urls import path
from .views import *

urlpatterns = [
    # 显示总用户路由
    #  http://127.0.0.1:8000/usercount/ 
    path('usercount/', display_user),

]