Declaring a validation schema other than MappingSchema may throw an uncaught exception

[ltvolks]

The colander.Mapping type is the only type that has the unknown attribute. During schema validation, this attribute is accessed.

Therefore any otherwise valid body will thrown an exception on validation if the declared schema type is not a colander.Mapping. Essentially this means anything other than a colander.MappingSchema.

Example:

import colander
from cornice.service import Service
from pyramid.config import Configurator
from webtest import TestApp


class ValidationSchema(colander.MappingSchema):
    key = colander.SchemaNode(colander.String())

class ListSchema(colander.SequenceSchema):
    key = colander.SchemaNode(colander.Int())

svc_validation = Service(name="test-validation", path="/test-validation")


@svc_validation.post(schema=ListSchema)
def post(request):
    return {"test": "succeeded"}


config = Configurator()
config.include("cornice")
config.scan()
app = config.make_wsgi_app()

client = TestApp(app)

# Throws an exception
# AttributeError: 'Sequence' object has no attribute 'unknown'
client.post_json('/test-validation', {'key': [1, 2, 3]})

Traceback:

  File "/venvs/cornice-test/src/cornice/cornice/service.py", line 495, in wrapper
    validate_colander_schema(args['schema'], request)
  File "/venvs/cornice-test/src/cornice/cornice/schemas.py", line 151, in validate_colander_schema
    if schema.colander_schema.typ.unknown == 'raise':
AttributeError: 'Sequence' object has no attribute 'unknown'

Somewhat related: #249

[tisdall]

Essentially this means anything other than a colander.MappingSchema.

Not exactly true...

>>> import colander
>>> x = colander.MappingSchema(colander.Sequence())
>>> x.typ
<colander.Sequence object at 0x7fb908fc6208>
>>> x.typ.unknown
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: 'Sequence' object has no attribute 'unknown'
>>> 

#309 fixes this issue

[leplatrem]

Schema typing was reworked in Cornice 2.0 (current master), and this may not apply anymore. Please reopen if your usecase is not covered by the new API. Thanks!