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'coerce' ignores 'nullable': True #269

andreymal opened this Issue Sep 25, 2016 · 3 comments


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andreymal commented Sep 25, 2016

>>> v = Validator({'foo': {'type': 'integer', 'coerce': int, 'nullable': True}})
>>> v.validate({'foo': None})
>>> v.errors
{'foo': ["field 'foo' cannot be coerced: int() argument must be a string, a bytes-like object or a number, not 'NoneType'"]}

but expected:

>>> v.validate({'foo': None})
>>> v.errors
>>> v.normalized({'foo': None})
{'foo': None}

This behavior can be logical (i can set something like 'coerce': lambda x: int(x) if x is not None else None), but I do not think it's convenient, because I have to specify nullable rule twice: in schema and in callable. I think, nullable should be checked first, and if value is None, then coerce callable should not be called.

If it's a bug and if architecture allows to fix this, please fix this :)

If it's a feature, please add a note about nullable in value coercion documentation (better with an example).


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funkyfuture commented Oct 26, 2016

this is similar to #268.


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belthaZornv commented Feb 27, 2017

Bump, this makes sense.. is there any possibility to get this?

funkyfuture added a commit to funkyfuture/cerberus that referenced this issue Apr 21, 2017


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sohaibfarooqi commented Nov 23, 2017

Is this feature released? I am using version 1.1, still facing this issue

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