Declare field validator with decorator

[JoMingyu]

When I define a model like this,

from schematics import Model
from schematics.types import *

class DummySchema(Model):
    from_ = DateType(
        serialized_name='from',
        required=True
    )
    to = DateType(
        serialized_name='to',
        required=True
    )

The way to specify additional validators for each field is as follows.

from schematics import Model
from schematics.exceptions import ValidationError
from schematics.types import *

def validate_year_of_to_is_2019(value):
    if value.year != 2019:
        raise ValidationError('year of to should be 2019.')

class DummySchema(Model):
    from_ = DateType(
        serialized_name='from',
        required=True
    )
    to = DateType(
        serialized_name='to',
        required=True,
        validators=[validate_year_of_to_is_2019]
    )

It would be nice if the field validator could be defined as a decorator.

from schematics import Model
from schematics.exceptions import ValidationError
from schematics.types import *

class DummySchema(Model):
    from_ = DateType(
        serialized_name='from',
        required=True
    )
    to = DateType(
        serialized_name='to',
        required=True
    )
    
    @to.validator
    def validate_year_of_to_is_2019(self, value):
        if value.year != 2019:
            raise ValidationError('year of to should be 2019.')

[ljluestc]

from schematics import Model
from schematics.exceptions import ValidationError
from schematics.types import *
from functools import wraps

def validate_year_of_to_is_2019(func):
@wraps(func)
def wrapper(self, value):
if value.year != 2019:
raise ValidationError('year of to should be 2019.')
return func(self, value)
return wrapper

class CustomDateType(DateType):
def init(self, *args, **kwargs):
super().init(*args, **kwargs)

def validator(self, func):
    return validate_year_of_to_is_2019(func)

class DummySchema(Model):
from_ = DateType(
serialized_name='from',
required=True
)
to = CustomDateType(
serialized_name='to',
required=True
)

@validate_year_of_to_is_2019
def validate_to_year(self, value):
    pass