colanderでDB絡みのチェックをかけるバリデータの検討

REDME.rst

使い方の想定

schema.bind(query=DBSession.query(Person).filter(Person.gender=='male')
           col=Person.first_name + " " + Person.last_name)

schema.py

import colander as c
from . import validators

@c.deferred
def bind_queryable(node, kw):
    return validators.QueryableValidator(kw["query"], kw["col"])

class PersonSchema(c.Schema):
    gender = c.SchemaNode(c.String(), validator=OneOf('male', 'female'))
    organization = c.SchemaNode(c.Integer, validator=bind_queryable))

validators.py

class QueryableValidator(object):
    def __init__(self, query, col):
        self.query = query
        self.col = col
    def __call__(self, node, value):
        if not self.query.filter(self.col==value).exists():
            raise Invalid

フィールド毎にbindしたい場合

s = PersonSchema()
s['organization'] = s['organization'].bind(
    query=DBSession.query(Person).filter(Person.gender=='male')
    col=Person.first_name + " " + Person.last_name)
)
s['other'] = s['other'].bind(....)
obj = s.deserialize(request.json)