Support for Cerberus 1.0 (work in progress)

"Work in progress" because we still have to wait for the Cerberus issue
"`readonly` conflicts with `default`" to be resolved.
(see pyeve/cerberus#268)

This is a rather big change. I still decided to do a single commit, as
intermediate commits would be in a non-working state anyway.

Breaking changes:

- `keyschema` was renamed to `valueschema` and `propertyschema` to
  `keyschema` (following changes in Cerberus).
- A PATCH on a document which misses a field having a default value will
  now result in setting this value, even if the field was not provided
  in the PATCH's payload.
- Error messages for `keyschema` are now returned as dictionary.
  Before: {'propertyschema_dict': 'propertyschema_dict'}
  Now: {'keyschema_dict': {'AAA': "value does not match regex '[a-z]+'"}}
- Error messages for `type` validations are different now (following
  changes in Cerberus).
- It is no longer valid to have a field with `default` = None and
  `nullable` = False.
  (see patch.py:test_patch_nested_document_nullable_missing)

In a nutshell, changes to the codebase are as follows:

- Add data layer independent subclass of `cerberus.Validator`
  * Support new signature of `__init__` and `validate`
  * Use `_config`-aware properties instead of bare member attributes to
    pass the `resource`, `document_id` and `persisted_document` to make
    them available to child validators
  * Add schema-docstrings to all `_validate_*` methods

- Adjust Mongo-specific `Validator` subclass
  * Adjust `_validate_type_*` methods (following changes in Cerberus)
  * Add schema-docstrings to all `_validate_*` methods

- Add custom ErrorHandler to support `VALIDATION_ERROR_AS_LIST`

- A few renames:
  * `ValidationError` -> `DocumentError`
  * `propertyschema` -> `keyschema` and `keyschema` -> `valueschema`

- Adjust tests due to different validation error messages
  (mostly for `type`)

- Remove `transparent_schema_rules` without replacement
- Remove `default`-handling, as Cerberus takes care of this now

eve/default_settings.py

@@ -228,9 +228,6 @@
 # don't allow unknown key/value pairs for POST/PATCH payloads.
 ALLOW_UNKNOWN = False
 
-# don't ignore unknown schema rules (raise SchemaError)
-TRANSPARENT_SCHEMA_RULES = False
-
 # Rate limits are disabled by default. Needs a running redis-server.
 RATE_LIMIT_GET = None
 RATE_LIMIT_POST = None

eve/flaskapp.py

@@ -19,7 +19,6 @@
 from werkzeug.serving import WSGIRequestHandler
 
 import eve
-from eve.defaults import build_defaults
 from eve.endpoints import collections_endpoint, item_endpoint, home_endpoint, \
     error_endpoint, media_endpoint, schema_collection_endpoint, \
     schema_item_endpoint
@@ -586,8 +585,6 @@ def _set_resource_defaults(self, resource, settings):
         settings.setdefault('auth_field',
                             self.config['AUTH_FIELD'])
         settings.setdefault('allow_unknown', self.config['ALLOW_UNKNOWN'])
-        settings.setdefault('transparent_schema_rules',
-                            self.config['TRANSPARENT_SCHEMA_RULES'])
         settings.setdefault('extra_response_fields',
                             self.config['EXTRA_RESPONSE_FIELDS'])
         settings.setdefault('mongo_write_concern',
@@ -600,12 +597,6 @@ def _set_resource_defaults(self, resource, settings):
         schema = settings.setdefault('schema', {})
         self.set_schema_defaults(schema, settings['id_field'])
 
-        # 'defaults' helper set contains the names of fields with default
-        # values in their schema definition.
-
-        # TODO support default values for embedded documents.
-        settings['defaults'] = build_defaults(schema)
-
         # list of all media fields for the resource
         settings['_media'] = [field for field, definition in schema.items() if
                               definition.get('type') == 'media']
@@ -686,12 +677,6 @@ def _set_resource_projection(self, ds, schema, settings):
                 ds['projection'] is not None:
             ds['projection'][self.config['DELETED']] = 1
 
-        # 'defaults' helper set contains the names of fields with default
-        # values in their schema definition.
-
-        # TODO support default values for embedded documents.
-        settings['defaults'] = build_defaults(schema)
-
         # list of all media fields for the resource
         settings['_media'] = [field for field, definition in schema.items() if
                               definition.get('type') == 'media']