python - 为什么 Django 迁移更改字段 (AlterField) 是没有被触及的？

Question

当我进行迁移时 python manage.py makemigrations wall我在控制台中看到 Django (1.8.12) 告诉我一长串被触及的字段:

Migrations for 'wall':
  0079_auto_20170302_0024.py:
    - Add field periodic_task_interval to userproject
    - Alter field bank_problems on bankireference
    - Alter field bank_problems_category on bankireference
    - Alter field bank_products on bankireference
    - Alter field bank_products_category on bankireference
    - Alter field extr_category on bankireference
    - Alter field extr_words on bankireference
    - Alter field neg_features on bankireference
    - Alter field neutral_features on bankireference
    - Alter field pos_features on bankireference
    - Alter field tonality_category on bankireference
    - Alter field tonality_words on bankireference
    - Alter field bank_problems on fbpagepost
    - Alter field bank_problems_category on fbpagepost
    - Alter field bank_products on fbpagepost
    - Alter field bank_products_category on fbpagepost
    - Alter field extr_category on fbpagepost

......等等，靠近所有的字段就是ManyToManyField。我还检查了其他迁移，看起来像是随机选择的字段，因为我也看到了 tagulous.models.fields.TagField乃至models.TextField。

但是，我确信 a 没有更改那些字段，甚至没有触及它们

这是 0079_auto_20170302_0024.py 中未触及字段的内容:

......
    migrations.AlterField(
        model_name='userproject',
        name='description',
        field=models.TextField(default='', verbose_name='Description', blank=True, null=True),
    ),
......

我唯一做的就是添加 - 将字段 periodic_task_interval 添加到 userproject 所以其他字段 - 为什么它们出现在迁移中？会不会因为数据库大而影响长时间的实际迁移？

Answer 1

如果您在字段中有 choices= 参数，您应该以“稳定的方式”(每次相同的顺序)生成它，例如使用 sorted()

TYPES = {
    'DISTRICT': 'Округ',
    'AREA': 'Район',
    'STATION': 'Станция метро',
}
type = models.CharField(
    max_length=255,
    choices=sorted(TYPES.items()),
    default='AREA',
)