valdiate_object: schema keys must be a subset of data keys

[H4rryK4ne]

Hi @bhch

thanks for this awesome library. I have a question to the implementation detail.

In validators.validate_object(...) you require, that all keys of the schema need to be present, even if they are not required.

Is there a special reason for this limitation?

I identified one possible "reason", in the loop starting at line L239. But this could be handled in a different way:

Instead of

for key in data:

One could do something like:

for key in {*data.keys(), *schema_keys}

If a key is not existing in data it could be handled like a key with None value.

Would you accept a PR for this change?

Best regards
Harry

[bhch]

Reasoning is to match Django's behaviour. More detailed answer: #109 (comment).

Can you give me some examples why you need this behaviour changed? What issues are you facing due to this?