python – Django 1.8将datefield更改为DateTimeField

2023年1月3日 315次阅读

我使用Django 1.8

我有这样的model.py

class Product(models.Model):

    name = models.CharField(max_length=150)
    created_at = models.DateField(auto_now_add = True)
    modified_at = models.DateField(auto_now = True)

MySQL有一个表’created_at’和’modified_at’谁有这样的数据“2015-11-02”
我想将数据更改为“2015-11-02 14:54:22”

我将models.py更改为此

class Product(models.Model):

    name = models.CharField(max_length=150)
    created_at = models.DateTimeField(auto_now_add = True)
    modified_at = models.DateTimeField(auto_now = True)

然后我在控制台中运行迁移

python manage.py makemigrations
python manage.py migrate

但什么都没发生. MySQL表中的数据不会改变,当我添加新信息时,在MySQL中添加旧模式的时间“2015-11-02”

我怎么改变它们？

PS到Lego Stormtroopr

Thanx,我读了Django教程,并编写了这段代码

from __future__ import unicode_literals
from django.db import migrations, models
import datetime

def add_time_to_date(apps, schema_editor):
    datetables = apps.get_model("product", "Product")
    delta = datetime.timedelta(hours=1)
    for x in datetables.objects.all():
        x.created_at = x.created_at + delta
        x.modified_at = x.modified_at + delta
        x.save()


class Migration(migrations.Migration):
    dependencies = [
        ('product', '0003_auto_20151110_1726'),
    ]

    operations = [
        migrations.RunPython(add_time_to_date),
     ]

在那之后,我跑了

   python manage.py migrate

Console写道：

    Operations to perform:
      Synchronize unmigrated apps: staticfiles, messages
      Apply all migrations: admin, contenttypes, product, auth, sessions
    Synchronizing apps without migrations:
      Creating tables...
        Running deferred SQL...
      Installing custom SQL...
    Running migrations:
      Rendering model states... DONE
      Applying product.0004_auto_20151110_1821.../home/djangojunior2/virtualpython2/lib/python2.7/site-packages/django/db/models/fields/__init__.py:1414: RuntimeWarning: DateTimeField Product.created_at         received a naive datetime (2015-11-02 00:00:00) while time zone support is active.
      RuntimeWarning)

    /home/djangojunior2/virtualpython2/lib/python2.7/site-packages/django/db/backends/mysql/base.py:124: Warning: Data truncated for column 'modified_at' at row 1
      return self.cursor.execute(query, args)

    /home/djangojunior2/virtualpython2/lib/python2.7/site-packages/django/db/models/fields/__init__.py:1414: RuntimeWarning: DateTimeField Product.created_at received a naive datetime (2015-11-08 00:00:00) while time zone support is active.
      RuntimeWarning)

    /home/djangojunior2/virtualpython2/lib/python2.7/site-packages/django/db/models/fields/__init__.py:1414: RuntimeWarning: DateTimeField Product.created_at received a naive datetime (2015-11-09 00:00:00) while time zone support is active.
      RuntimeWarning)

    /home/djangojunior2/virtualpython2/lib/python2.7/site-packages/django/db/models/fields/__init__.py:1414: RuntimeWarning: DateTimeField Product.created_at received a naive datetime (10 00:00:00) while time zone support is active.
      RuntimeWarning)

     OK

我检查了Mysql db(使用了mysql-console),没有任何反应.日期仍然是“2015-11-02”如果我添加新数据,在表modified_at和created_at中,日期添加到旧样式(“2015-11-02”).

我究竟做错了什么？

最佳答案 migrate命令仅处理架构迁移,而不处理数据迁移.部分问题是许多数据库后端在同一字段类型中存储日期和日期时间,并且Django将它们强制转换为正确的类型.

所以要做到这一点你也需要做data migration.

迁移的代码看起来像这样,但它取决于添加到无时间日期的时间：

from django.db import models, migrations

def date_to_datetime(apps, schema_editor):
    # We can't import the Person model directly as it may be a newer
    # version than this migration expects. We use the historical version.
    Product = apps.get_model("yourappname", "Product")
    for product in Product.objects.all():
        # convert a date to a date time on the product instance
        product.save()

class Migration(migrations.Migration):

    dependencies = [
        ('yourappname', 'migration_name'),
    ]

    operations = [
        migrations.RunPython(date_to_datetime),
    ]
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