我应该 base64 编码 pickle 发送 over.network/store 到 db 吗？

Question

Pickle is a way to serialize the python object.

Suppose I want to send this over the.network or store in a database, then can I send/store (respectively) the pickle value or do I need to base64 encode the pickle value?

Answer 1

JSON representations are strings. But even when I have JSON-serialized strings that contain Unicode characters that are not in the printable ASCII character set range, Python chooses a representation of these characters that are in the ASCII-printable range by default ( ensure_ascii=True is the default value for the json.dumps call). For example:

print(json.dumps('圣诞节\n\000'));

Prints:

"\u5723\u8bde\u8282\n\u0000"

There is nothing in the above serialized representation that requires special encoding. Now the issue is whether the object that you wish to serialize requires special encoding. For example, if the object has an attribute that is of type decimal.Decimal , which is not one of the supported JSON-serializable types, you would want to store the the string representation of this attribute.

For example:

from decimal import Decimal
import json

class MyClass:
    def __init__(self, a: int, b: Decimal):
        self.a = a
        self.b = b

    def __repr__(self):
        return f'a = {self.a}, b = {self.b}'

    def serialize(self):
        return json.dumps({'a': self.a, 'b': str(self.b)})

    @classmethod
    def deserialize(cls, s):
        state = json.loads(s)
        return cls(state['a'], Decimal(state['b']))

obj1 = MyClass(3, Decimal('7.93'))
print('obj1:', obj1)
saved_state = obj1.serialize()
print('Saved state:', saved_state)
obj2 = MyClass.deserialize(saved_state)
print('obj2:', obj2)

Prints:

obj1: a = 3, b = 7.93
Saved state: {"a": 3, "b": "7.93"}
obj2: a = 3, b = 7.93

Note

If you named your methods __getstate__ (instead of serialize ) and __setstate__ (instead of deserialize ) and made the latter a regular instance method rather than a class method, then the class would also be compatible with the pickle module, though you need to think about whether you would want to use the standard pickling methodology for when you do not need to send the object across the wire or have it saved in a database or don't need the data-representation stability.