Django TruncDate提供空值

Question

我正在使用Django 2.2

我使用Django查询筛选记录，如

from datetime import datetime
from django.db.models.functions import TruncDate

start_date = datetime.strptime('2020-02-01', '%Y-%m-%d').date()
end_date = datetime.strptime('2020-03-31', '%Y-%m-%d').date()

lead_list = LeadList.objects.all()

# Filter query
query = LeadListEntry.objects.filter(
    lead_list__in=lead_list
  )

# Filter by start date
query = query.filter(
    created__gte=start_date
  )

# Filter by end date
query = query.filter(
    created__lte=end_date
  )

# Annotate date
query = query.annotate(
     created_date=TruncDate('created')
   ).order_by(
     'created_date'
   ).values('created_date').annotate(
     **{'total': Count('created')}
   )

生成的SQL查询是

SELECT 
    DATE(CONVERT_TZ(`lead_generation_leadlistentry`.`created`, 'UTC', 'UTC')) AS `created_date`, 
    COUNT(`lead_generation_leadlistentry`.`created`) AS `total`
FROM `lead_generation_leadlistentry` 
WHERE (
    `lead_generation_leadlistentry`.`lead_list_id` IN (
        SELECT 
            U0.`id` FROM `lead_generation_leadlist` U0 
        WHERE 
            U0.`deleted` IS NULL
    )
    AND `lead_generation_leadlistentry`.`created` >= '2020-02-01 00:00:00' 
    AND `lead_generation_leadlistentry`.`created` <= '2020-03-31 00:00:00'
)
GROUP BY DATE(CONVERT_TZ(`lead_generation_leadlistentry`.`created`, 'UTC', 'UTC'))
ORDER BY `created_date` ASC

这在本地服务器和临时服务器上表现不同

本地开发服务器

+--------------+-------+
| created_date | total |
| ------------ | ----- |
| 2020-02-25   | 15    |
| 2020-02-27   | 10    |
+--------------+-------+

临时服务器

+--------------+-------+
| created_date | total |
| ------------ | ----- |
| null         | 15    |
+--------------+-------+

日期列为null

注意：Django的时区由USE_TZ=True启用

LeadListEntry型号

class LeadListEntry(models.Model):
    lead_list = models.ForeignKey(LeadList, on_delete=models.CASCADE, related_name='lead_list_entry')
    data = models.TextField(help_text='Lead List entry data. (JSON data)', blank=False)

    created = models.DateTimeField(auto_now_add=True)
    modified = models.DateTimeField(auto_now=True)

Answer 1

从本地到登台的不同结果的问题可能会发生，因为机器的日期时间不同，我以前在windows上开发时得到过这个问题，但是登台是ubuntu，结果是strptime()日期参数不同，并且不断显示错误

对于日期筛选，作为代码示例，您不必创建日期对象，只需使用正确的字符串日期格式即可

start_date = '2020-02-01'
end_date = '2020-03-31'

那就照常去吧

我想做这样的事情

# As you only need LeadList id's for foreginkey filtering, this is more optimized
lead_list = LeadList.objects.all().values_list('id')

# Filter query
query = LeadListEntry.objects.filter(
    lead_list__in=lead_list, created__date__gte = start_date, created__date__lte=end_date
  )

并按日期分组

query = query.values('created__date').annotate(count=Count('created__date')).order_by('created__date')

Answer 2

下面是用户遇到相同错误时的解决方案

错误不在Django上，而是在MySQL数据库设置上

日期字段返回null，因为CONVERT_TZ不起作用。这可能是因为MySQL数据库中没有时区数据

要导入时区数据，请执行以下命令

mysql_tzinfo_to_sql /usr/share/zoneinfo | mysql -u root -p mysql

导入后，重新启动mysql服务器