django 动态获取创建model

最新推荐文章于 2025-01-22 00:49:58 发布

manitoHan

最新推荐文章于 2025-01-22 00:49:58 发布

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CC 4.0 BY-SA版权

文章标签： django 数据库 sqlite

本文链接：https://blog.youkuaiyun.com/hyfand1/article/details/134571698

文章介绍了如何在Django中动态创建表，使用LogMetaclass自定义Model，处理Model注册时的警告，并在需要时通过日期动态生成表结构并保存数据。

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动态的创建表

def get_log_model(prefix):
    table_name = 'log_%s' % str(prefix)

    LOG_LEVELS = (
        (0, 'DEBUG'),
        (10, 'INFO'),
        (20, 'WARNING'),
    )

    class LogMetaclass(models.base.ModelBase):
        def __new__(cls, name, bases, attrs):
            name += '_' + prefix  # 这是Model的name.
            return models.base.ModelBase.__new__(cls, name, bases, attrs)

    class Log(models.Model):
        __metaclass__ = LogMetaclass
        level = models.IntegerField(choices=LOG_LEVELS)
        msg = models.TextField()
        time = models.DateTimeField(auto_now=True, auto_now_add=True)

        @staticmethod
        def is_exists():
            return table_name in connection.introspection.table_names()

        class Meta:
            db_table = table_name

    return Log

def index(request):
    today = date.today().strftime("%Y%m%d")

    # RuntimeWarning: Model '__main__.logclasslog_' was already registered.
    # Reloading models is not advised as it can lead to inconsistencies
    # most notably with related models.
    # 如上述警告所述, Django 不建议重复加载 Model 的定义.
    # 作为 demo 可以直接通过get_log_model获取，无视警告.
    # 所以这里先通过 all_models 获取已经注册的 Model,
    # 如果获取不到， 再生成新的模型.
    try:
        cls = apps.get_model('__main__', 'Log_%s' % today)
    except LookupError:
        cls = get_log_model(today)

    if not cls.is_exists():
        with connection.schema_editor() as schema_editor:
            schema_editor.create_model(cls)

    log = cls(level=10, msg="Hello")
    log.save()

    return HttpResponse('<h1>%s</h1>' % cls._meta.db_table)