fix(fcm): String representation in Message class

[lahirumaramba]

Discussion

• Add string representation in Message class
• Use MessageEncoder to convert Message objects to valid JSON strings

Testing

• None

API Changes

• None

Resolves: #349

RELEASE NOTE: Message class now implements the __str__() contract which can be used to obtain a string representation of a Message instance.

[lahirumaramba]

Sample output:

>>> from firebase_admin import messaging
>>> message = messaging.Message(
        data={
            'score': '850',
            'time': '2:45',
        },
        token='token',
    )
>>> print(message)
{"token": "token", "data": {"score": "850", "time": "2:45"}}
>>> str(message)
'{"token": "token", "data": {"score": "850", "time": "2:45"}}'
>>>

[hiranya911]

One suggestion added.

This also brings up the question whether we should support __str__ on all public classes in this module (e.g. AndroidConfig, Notification etc). But Message is probably enough to begin with. After all, other objects are never used by themselves -- they are always part of a Message.

Also please add a test case.

[hiranya911]

Would this work?

json.dumps(self, cls=MessageEncoder)

[lahirumaramba]

Yes! Thank you.
Will update with test cases soon.

[lahirumaramba]

@hiranya911 :

One suggestion added.

This also brings up the question whether we should support __str__ on all public classes in this module (e.g. AndroidConfig, Notification etc). But Message is probably enough to begin with. After all, other objects are never used by themselves -- they are always part of a Message.

Also please add a test case.

• Good point! I also thought about adding __str__ support to all other classes but like you said they will always be part of a Message. I think we can start with Message for now.

• PR is updated with test cases.

• One other thing to note is that since we use MessageEncoder in the implementation, __str__ inherits the validation checks from MessageEncoder... I do not think this is a problem but wanted to mention as this could be different from the expected behavior of a str() function.

[hiranya911]

LGTM :+1