使用Django中的filter方法进行数据查询的基本操作_Python

基本用法

1. 等于 (=)

results = mymodel.objects.filter(title='example')

2. 不等于 (exclude)

results = mymodel.objects.exclude(title='example')

3. 大于 (gt) / 大于等于 (gte)

results = mymodel.objects.filter(price__gt=10)
results = mymodel.objects.filter(price__gte=10)

4. 小于 (lt) / 小于等于 (lte)

results = mymodel.objects.filter(price__lt=10)
results = mymodel.objects.filter(price__lte=10)

5. 包含 (contains) / 不包含 (exclude + contains)

results = mymodel.objects.filter(title__contains='example')
results = mymodel.objects.exclude(title__contains='example')

6. 开始于 (startswith) / 结束于 (endswith)

results = mymodel.objects.filter(title__startswith='ex')
results = mymodel.objects.filter(title__endswith='ple')

7. 正则表达式匹配 (__regex)

results = mymodel.objects.filter(title__regex=r'^ex.*')

8. 是否为空 (__isnull)

results = mymodel.objects.filter(price__isnull=true)
results = mymodel.objects.filter(price__isnull=false)

组合查询

1. and 条件

results = mymodel.objects.filter(title='example', price__gt=10)

2. or 条件 (使用 q 对象)

from django.db.models import q

results = mymodel.objects.filter(q(title='example') | q(price__gt=10))

in 查询

1. __in 查询

results = mymodel.objects.filter(id__in=[1, 2, 3])

日期查询

1. 日期字段 (date, year, month, day, __week_day)

results = mymodel.objects.filter(created_at__date='2024-05-21')
results = mymodel.objects.filter(created_at__year=2024)
results = mymodel.objects.filter(created_at__year=2024, created_at__month=5)
results = mymodel.objects.filter(created_at__year=2024, created_at__month=5, created_at__day=21)

外键字段查询

1. 跨表查询

results = mymodel.objects.filter(user__email='example@example.com')

示例代码

# 导入必要的模块和类
from django.db import models

# 创建模型类
class mymodel(models.model):
    title = models.charfield(max_length=100)
    price = models.decimalfield(max_digits=10, decimal_places=2)
    created_at = models.datetimefield()

# 使用 filter 方法进行数据查询
results = mymodel.objects.filter(title='example', price__gt=10)

# 打印结果
for result in results:
    print(result)

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