为什么 django 1.7 会为字段选择的变化创建迁移? [英] Why does django 1.7 creates migrations for changes in field choices?

问题描述

我在 1.7 版上观察到了这种行为，但在以前使用南迁移的版本中没有.

I have observed this behaviour on version 1.7 but not in previous versions using south migration.

例如.

class RedemptionCode(models.Model):
    EXPIRE_OPTIONS = (
        ('1 week', '1 Week'),
    )

    expire_option = models.CharField(max_length=255, choices=EXPIRE_OPTIONS)

当我添加更多选项时:

EXPIRE_OPTIONS = (
    ('1 week', '1 Week'),
    ('2 weeks', '2 Weeks'),
    ('1 month', '1 Month'),
    ('1 day', '1 Day'),
)

并运行 makemigrations，它会为它创建一个迁移，来自 south 背景 我认为它应该说没有检测到更改，因为它不会影响数据库架构.我不知道它有什么用途:

and run makemigrations, it creates a migration for it, coming from south background I thought it should say no changes detected as it doesn't affects database schema. I don't know what purpose it serves:

class Migration(migrations.Migration):

    dependencies = [
        ('credits', '0001_initial'),
    ]

    operations = [
        migrations.AlterField(
            model_name='redemptioncode',
            name='expire_option',
            field=models.CharField(max_length=255, choices=[('1 week', '1 Week'), ('2 weeks', '2 Weeks'), ('1 month', '1 Month'), ('1 day', '1 Day')]),
        ),
    ]

推荐答案

在提单因重复被封后，终于找到了答案:

After raised the ticket and got closed due to duplication, finally found the answer:

这是设计使然.有几个原因，尤其是对我而言，历史上的数据迁移需要对模型进行完全准确的表示，包括它们的所有选项，而不仅仅是影响数据库的选项.

This is by design. There are several reasons, not least of which for me that datamigrations at points in history need to have a full accurate representation of the models, including all their options not just those which affect the database.

参考:

• https://code.djangoproject.com/ticket/22837
• https://code.djangoproject.com/ticket/23581

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