Django QuerySet对象，filter()方法

 filter()方法 用于实现数据过滤功能，相当于sql语句中的where子句。

filter(字段名__gt=10)

类似SQL中的 >10

filter(price__lt=29.99)

filter(字段名__gte=10, 字段名__lte=20)

类似sql中的 >=10 and <=10使用filter()方法获取所有价格在10到20之间的书籍

    # books = Book.objects.filter(price__gte=10, price__lte=20)  # __gte是“greater than or equal to”（大于等于）的缩写，__lte是“less than or equal to”（小于等于）的缩写。# books = Book.objects.filter(price__gt=10)   # 在Django的ORM（对象关系映射）查询中，__gt是过滤条件的一个特殊语法，用于表示“大于”（greater than）。books = Book.objects.filter(price__lt=29.99)   # __lt 是“less than”（小于）的缩写。

1，添加模型

Test/app11/models.py

from django.db import modelsclass Post(models.Model):title = models.CharField(max_length=200)content = models.TextField()pub_date = models.DateTimeField('date published')class Book(models.Model):title = models.CharField(max_length=100)author = models.CharField(max_length=100)publication_date = models.DateField()price = models.DecimalField(max_digits=5, decimal_places=2)def __str__(self):return self.title

2，添加视图函数

Test/app11/views.py

from django.shortcuts import render
from .models import Postdef index(request):posts = Post.objects.all()return render(request, '11/index.html', {'posts': posts})# apps/books/views.pyfrom django.shortcuts import render
from .models import Bookdef book_list_view(request):# 使用filter()方法获取所有价格在10到20之间的书籍books = Book.objects.filter(price__gte=10, price__lte=20)return render(request, '11/book_list.html', {'books': books})

3，添加路由地址

Test/app11/urls.py

from django.urls import path
from . import viewsurlpatterns = [path('index/', views.index, name='index'),path('book_list_view/', views.book_list_view, name='book_list_view'),
]

4，执行迁移

python manage.py makemigrations app11python manage.py migrate app11

5，创建示例数据

Test/create_books.py

import os
import django# 设置Django环境，需要指定settings模块
os.environ.setdefault("DJANGO_SETTINGS_MODULE", "Test.settings")
django.setup()from app11.models import Bookdef create_books():# 创建示例书籍book1 = Book(title="Python编程", author="小强", publication_date="2022-01-01", price=15.99)book2 = Book(title="Django Web开发", author="小龙", publication_date="2022-04-15", price=29.99)book3 = Book(title="算法导论", author="小龙", publication_date="2024-07-20", price=19.99)book4 = Book(title="java入门到弃坑", author="余胜军", publication_date="2019-02-20", price=39.99)book5 = Book(title="c入门到弃坑", author="小龙", publication_date="2012-07-20", price=9.99)book6 = Book(title="c++入门到弃坑", author="小6", publication_date="2024-02-20", price=13.99)book7 = Book(title="python多线程入门", author="小6", publication_date="2025-02-20", price=49.99)# 保存书籍到数据库book1.save()book2.save()book3.save()book4.save()book5.save()book6.save()book7.save()print("数据创建成功！")if __name__ == "__main__":create_books()

6，访问页面  

 http://127.0.0.1:8000/app11/book_list_view/

可以看到10到20块的书籍数据都展示出来了