[英]How to convert this complex query to Django ORM equivalent
楷模:
Items(models.Model):
name = models.CharField(max_length=250, verbose_name="Item Name")
created_date = models.DateTimeField(auto_now_add=True)
Accounts(models.Model):
user = models.ForeignKey(User, on_delete=models.CASCADE, null=True)
url_tag = models.CharField(max_length=200)
item = models.ForeignKey(Items, on_delete=models.CASCADE)
Comments(models.Model):
item = models.ForeignKey(Items, on_delete=models.CASCADE, null=True)
comment = models.TextField(null=True)
url_tag = models.URLField(null=True)
is_flagged = models.BooleanField(default=False, null=True)
response_required = models.BooleanField(default=True)
created_date = models.DateTimeField(auto_now_add=True)
Responses(models.Model):
response = models.TextField()
comment = models.ForeignKey(Comments, on_delete=models.CASCADE)
created_date = models.DateTimeField(auto_now_add=True)
查詢:
select c.id as comment_id, c.created_date, c.is_flagged, c.response_required
from comments as c
left join responses as r on c.id = r.comment_id
inner join items as i on i.id = c.item_id and r.comment_id is null
left join accounts as a on
(a.item_id = c.item_id and lower(a.url_tag) = lower(c.url_tag)
where c.id in (12, 32, 42, 54)
ORDER BY c.created_date desc, comment_id desc;
我試過的:
filters = {
'id__in': [12, 32, 42, 54]
}
comment_objs = Comment.objects.filter(**filters)
.select_related('commentsresponses', 'item')
.order_by('-created_date', '-id')
我想在加入和應用過濾器后獲取評論對象列表。
也許我們可以在這里使用序列化程序,我不知道,因為我對 django 沒有太多經驗
如果時間復雜度對您來說無關緊要,您可以使用原始 SQL 查詢:
from django.db import connection
cursor = connection.cursor()
cursor.execute('''select c.id as comment_id, c.created_date, c.is_flagged,
c.response_required
from comments....''')
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