Populate nested objects what only support kwargs for initialization?

Question

I have some python library with Record class. Record class accepts data using only kwargs. I populate Records like this and it works ok:


class Animal(Record):
    name = String(required=True)


animal = Animal(**{'name': 'joe'})

The library also supports nesting Records like this:

class Fur(Record):
    color = String(required=True)


class Animal(Record):
    fur = Fur(required=True)

However when I try to populate with:

animal = Animal(**{'fur': {'color': 'red'}})

it fails because the subrecord do not receive color=red but receives {'color': 'red'} instead.

So I would need a kind of "recursive **" ?

it is here: https://github.com/apache/pulsar/blob/master/pulsar-client-cpp/python/pulsar/schema/definition.py — JOhn, Aug 26 '19 at 07:13
For the record, you know that you could write it like this, right? `animal = Animal(name = 'joe')` — olinox14, Aug 27 '19 at 15:25
yes but goal is to populate Record with nested JSON directly — JOhn, Aug 27 '19 at 16:59

score 2 · Answer 1 · edited Oct 02 '19 at 05:19

What about simply doing:

animal = Animal(fur = Fur(color = 'red'))

A little more about kwargs: What is the purpose and use of **kwargs?

Though, I don't think you can you can do it with a raw dictionary like this. If you take a look at the __init__ (here) of the Record class, you'll see that the kwargs just override the default value of the field and is set with setattr. So if you do animal = Animal(**{'fur': {'color': 'red'}}), you simply affect the dictionary {'color': 'red'} to the field fur.

The only way I can think of would be to override the Record class, for example something like this (not tested):

class SRecord(Record):
    def __setattr__(self, key, value):
        if type(self._fields.get(key, None)) is SRecord:
            value = SRecord(value)
        super(SRecord, self).__setattr__(key, value)

goal is to populate Record with nested JSON directly – JOhn Aug 27 '19 at 16:52 — JOhn, Aug 27 '19 at 16:52

Populate nested objects what only support kwargs for initialization?

1 Answers1