Django ORM 批量更新

发布于 2025-01-16 17:12:03 字数 699 浏览 2 评论 0原文

我一直坚持这个任务。我有教授模型，我需要更新 2 个查询，但我的数据库中有 6 个查询。

from django.db import models

class Professor(models.Model):
   first_name = models.CharField(max_length=30)
   last_name = models.CharField(max_length=30)
   age = models.IntegerField(default=18)

我的职能。

def update_professor_first_names():
    first_name_updates = [(1, 'freddie'), (2, 'mady'), (3, 'hady'), (4, 'michael'), (5, 'rose')]
    tmp = []
    for prof_id, new_first_name in first_name_updates:
        prof = Professor.objects.get(id=prof_id)
        prof.first_name = new_first_name
        tmp.append(prof)
    Professor.objects.bulk_update(tmp, ['first_name'])

请给我一些建议。

原文

I have stuck on this task.
I have Professor model and i need to update from 2 queries but i have 6 queries in my DB.

from django.db import models

class Professor(models.Model):
   first_name = models.CharField(max_length=30)
   last_name = models.CharField(max_length=30)
   age = models.IntegerField(default=18)

My function.

def update_professor_first_names():
    first_name_updates = [(1, 'freddie'), (2, 'mady'), (3, 'hady'), (4, 'michael'), (5, 'rose')]
    tmp = []
    for prof_id, new_first_name in first_name_updates:
        prof = Professor.objects.get(id=prof_id)
        prof.first_name = new_first_name
        tmp.append(prof)
    Professor.objects.bulk_update(tmp, ['first_name'])

Please give me some advices.

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鸵鸟症 2025-01-23 17:12:03

现在，您正在对每个 ID 运行 get，这会生成 5 个查询，然后运行一个更新查询，总共 6 个查询。

您可以使用 __in 运算符与所有 ID 一起运行一个查询来获取您想要更新的教授，然后在分配名称后运行批量更新，总共两个查询：

id_set = [id for id, first_name in first_name_updates]
profs_to_update = Professor.objects.filter(id__in=id_set)

for prof in profs_to_update:
    prof.first_name = next(first_name for id, first_name in first_name_updates if id == prof.id)

Professor.objects.bulk_update(profs_to_update, ['first_name'])

right now you're running a get on every ID which generates 5 queries, then one for the update, which totals 6 queries.

you can use the __in operator with all of the IDs to run one query getting the professors you want to update, then run the bulk update after you've assigned the names, for two queries total:

id_set = [id for id, first_name in first_name_updates]
profs_to_update = Professor.objects.filter(id__in=id_set)

for prof in profs_to_update:
    prof.first_name = next(first_name for id, first_name in first_name_updates if id == prof.id)

Professor.objects.bulk_update(profs_to_update, ['first_name'])

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