[英]Defining a table with sqlalchemy with a mysql unix timestamp
Background, there are several ways to store dates in MySQ. 背景技术,有几种方法可以在MySQ中存储日期。
As a MySQL Date field, another mysql specific data type. 作为MySQL Date字段,是另一个MySQL特定的数据类型。
It's very important not to confuse case 2 with case 3 (or case 4). 不要混淆案例2和案例3(或案例4),这一点非常重要。 I have an existing table with an integer date field (case 2) how can I define it in sqlalchemy in a way I don't have to access mysql's "FROM_UNIXTIME" function?
我有一个带有整数日期字段的现有表(案例2),如何在sqlalchemy中定义它,而不必访问mysql的“ FROM_UNIXTIME”函数?
For the record, just using sqlalchemy.types.DateTime and hoping it does the right thing when it detects an integer column doesn't work, it works for timestamp fields and date fields. 作为记录,仅使用sqlalchemy.types.DateTime并希望它在检测到整数列时做正确的事情不起作用,它适用于时间戳记字段和日期字段。
I think there is a couple of issues with the type decorator you showed. 我认为您显示的类型装饰器存在两个问题。
impl
should be sqlalchemy.types.Integer
instead of DateTime
. impl
应该是sqlalchemy.types.Integer
而不是DateTime
。 Here's the what I have in mind: 这就是我的想法:
import datetime, time
from sqlalchemy.types import TypeDecorator, DateTime, Integer
class IntegerDateTime(TypeDecorator):
"""a type that decorates DateTime, converts to unix time on
the way in and to datetime.datetime objects on the way out."""
impl = Integer # In schema, you want these datetimes to
# be stored as integers.
def process_bind_param(self, value, _):
"""Assumes a datetime.datetime"""
if value is None:
return None # support nullability
elif isinstance(value, datetime.datetime):
return int(time.mktime(value.timetuple()))
raise ValueError("Can operate only on datetime values. "
"Offending value type: {0}".format(type(value).__name__))
def process_result_value(self, value, _):
if value is not None: # support nullability
return datetime.datetime.fromtimestamp(float(value))
So yeah, this approach works. 是的,这种方法有效。 And I ended up answering my own question :/, hope somebody finds this useful.
最后我回答了我自己的问题:/,希望有人觉得这有用。
import datetime, time
from sqlalchemy.types import TypeDecorator, DateTime
class IntegerDateTime(TypeDecorator):
"""a type that decorates DateTime, converts to unix time on
the way in and to datetime.datetime objects on the way out."""
impl = DateTime
def process_bind_param(self, value, engine):
"""Assumes a datetime.datetime"""
assert isinstance(value, datetime.datetime)
return int(time.mktime(value.timetuple()))
def process_result_value(self, value, engine):
return datetime.datetime.fromtimestamp(float(value))
def copy(self):
return IntegerDateTime(timezone=self.timezone)
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