def __init__(self, _json_schema_folders=[], _uri_handlers=None):
"""
Initiate the SchemaTools class
:param _json_schema_folders: A list of folders where schema files are stored
:param : _uri_handlers: A dict of uri_handlers, resolves a URI prefix to a actual schema.
"""
if not _json_schema_folders:
_json_schema_folders = []
if not _uri_handlers:
self.uri_handlers = {}
else:
self.uri_handlers = _uri_handlers
# All methods that have no handlers should use the cache handler.
for _curr_key, _curr_value in _uri_handlers.items():
if _curr_value is None:
_uri_handlers[_curr_key] = self.cache_handler
self.resolver = RefResolver(base_uri="",
handlers=self.uri_handlers, referrer=None, cache_remote=True)
self.mongodb_validator = MongodbValidator(resolver= self.resolver)
self.json_schema_objects = {}
# Load application specific schemas
for _curr_folder in _json_schema_folders:
_loaded_uris = self.load_schemas_from_directory(os.path.abspath(_curr_folder))
# Resolve all the schemas
for _curr_uri in _loaded_uris:
self.json_schema_objects[_curr_uri] = self.resolveSchema(self.json_schema_objects[_curr_uri])
write_to_log("Schemas loaded and resolved: " +
str.join(", ", ["\"" +_curr_schema["title"] + "\"" for _curr_schema in self.json_schema_objects.values()])
, _category=EC_NOTIFICATION, _severity=SEV_DEBUG)
class SchemaTools():
"""
The schema tools class does all the handling, validation and transformation of schemas in the optimal framework.
"""
# The json_schema_objects keeps the parsed and instantiated schema objects.
json_schema_objects = None
# json_schema_folder is the folder of where the json schemas are kept
json_schema_folders = None
# The resolve is responsible for resolving URI prefixes referencing other schemas,
resolver = None
# The URI-handlers are a dict of callbacks, used when resolving URI:s.
uri_handlers = None
# An instance of the mongodb JSON validator.
mongodb_validator = None
# Default handler, will only look at the cache
def cache_handler(self, _uri):
print ("fetching " + _uri)
if _uri in self.json_schema_objects:
return self.json_schema_objects[_uri]
else:
return None
# noinspection PyDefaultArgument
def __init__(self, _json_schema_folders=[], _uri_handlers=None):
"""
Initiate the SchemaTools class
:param _json_schema_folders: A list of folders where schema files are stored
:param : _uri_handlers: A dict of uri_handlers, resolves a URI prefix to a actual schema.
"""
if not _json_schema_folders:
_json_schema_folders = []
if not _uri_handlers:
self.uri_handlers = {}
else:
self.uri_handlers = _uri_handlers
# All methods that have no handlers should use the cache handler.
for _curr_key, _curr_value in _uri_handlers.items():
if _curr_value is None:
_uri_handlers[_curr_key] = self.cache_handler
self.resolver = RefResolver(base_uri="",
handlers=self.uri_handlers, referrer=None, cache_remote=True)
self.mongodb_validator = MongodbValidator(resolver= self.resolver)
self.json_schema_objects = {}
# Load application specific schemas
for _curr_folder in _json_schema_folders:
_loaded_uris = self.load_schemas_from_directory(os.path.abspath(_curr_folder))
# Resolve all the schemas
for _curr_uri in _loaded_uris:
self.json_schema_objects[_curr_uri] = self.resolveSchema(self.json_schema_objects[_curr_uri])
write_to_log("Schemas loaded and resolved: " +
str.join(", ", ["\"" +_curr_schema["title"] + "\"" for _curr_schema in self.json_schema_objects.values()])
, _category=EC_NOTIFICATION, _severity=SEV_DEBUG)
@staticmethod
def check_schema_fields(_curr_schema_obj, _curr_file):
""" Check so all mandatory fields are in the schema
:param _curr_schema_obj: Schema to check
:param _curr_file: File name use in error message
"""
def raise_field_error(_collection):
raise Exception("Schematools.check_schema_fields: The \"" + _collection + "\"" +
" field is not in the schema-\"" + _curr_file + "\"")
if "version" not in _curr_schema_obj:
raise_field_error("version")
def load_schema_from_file(self, _file_name):
"""
Loads a specified schema from a file, checks it and stores it in the schema cache.
:param _file_name: The name of the schema file
"""
try:
_curr_file = open(_file_name, "r")
except Exception as e:
raise Exception("load_schema_from_file: Error loading \"" + _file_name +
"\": " + str(e))
try:
_json_schema_obj = json.load(_curr_file)
except Exception as e:
raise Exception("load_schema_from_file: Error parsing \"" + _file_name +
"\"" + str(e))
_curr_file.close()
try:
self.check_schema_fields(_json_schema_obj, _file_name)
except SchemaError as scherr:
raise Exception("load_schema_from_file: SchemaError in " + _file_name + " at path:" + str(
scherr.path) + "\nMessage:\n" + str(scherr.message))
except Exception as e:
raise Exception("load_schema_from_file: schema validation in " + _file_name + ", error :" + str(e))
return _json_schema_obj
def load_schemas_from_directory(self, _schema_folder, _destination = None):
"""
Load and validate all schemas in a folder structure, add to json_schema_objects
:param _schema_folder: Where to look
"""
_loaded_uris = []
if _destination == None:
_destination = self.json_schema_objects
def _recurse(_folder):
for _root, _dirs, _files in os.walk(_folder):
for _file in _files:
if _file[-5:].lower() == ".json":
_ref = "ref://" + ".".join(os.path.relpath(_root, _schema_folder).split(os.path.sep) + [_file[0:-5]])
_destination[_ref] = self.load_schema_from_file (os.path.join(_root, _file))
if _ref not in _loaded_uris:
_loaded_uris.append(_ref)
for _dir in _dirs:
_recurse(os.path.join(_folder, _dir))
_recurse(_schema_folder)
return _loaded_uris
def apply(self, _data, _schema_ref=None):
"""
Validate the JSON in _data against a JSON schema.
:param _data: The JSON data to validate
:param _schema_ref: If set, validate against the specified schema, and not the one in the data.
:return: the schema object that was validated against.
"""
if _schema_ref is not None:
_json_schema_obj = self.json_schema_objects[_schema_ref]
else:
if "schemaRef" in _data:
try:
_json_schema_obj = self.json_schema_objects[_data["schemaRef"]]
except KeyError as e:
raise Exception("SchemaTools.apply, invalid schemaRef: " + _data["schemaRef"])
else:
raise Exception("SchemaTools.apply, data must have a schemaRef attribute")
self.mongodb_validator.apply(_data, _json_schema_obj)
return _data, _json_schema_obj
def validate(self, _data, _schema_ref=None):
"""
Validate the JSON in _data against a JSON schema.
:param _data: The JSON data to validate
:param _schema_ref: If set, validate against the specified schema, and not the one in the data.
:return: the schema object that was validated against.
"""
if _schema_ref is not None:
_json_schema_obj = self.json_schema_objects[_schema_ref]
else:
_json_schema_obj = self.json_schema_objects[_data["schemaRef"]]
self.mongodb_validator.validate(_data, _json_schema_obj)
return _data, _json_schema_obj
def non_base_type(self, _type):
if _type not in ["array", "string", "integer", "object"]:
return [_type]
else:
return []
def resolveSchema(self, _schema):
"""
Recursively resolve all I{$ref} JSON references in a JSON Schema.
:param _schema: A L{dict} with a JSON Schema.
:return: The resolved JSON Schema, a L{dict}.
"""
_result = deepcopy(_schema)
def local_resolve(_obj, _ref_history):
"""
Recurse the JSON-tree and see where there are unresolved remote references.
:param _obj: The node to resolve
:param _ref_history: The previously resolved remote references, for cyclical check
"""
if isinstance(_obj, list):
# Loop any list
for item in _obj:
local_resolve(item, _ref_history)
return
if isinstance(_obj, dict):
if "$ref" in _obj:
_curr_ref = _obj["$ref"]
# Do not resolve local references
if _curr_ref[0] == "#":
return
# Check for cyclical references
if _curr_ref in _ref_history:
raise Exception("Error, cyclical remote reference: " + str(_curr_ref) + ": Formers " + str(_ref_history))
with self.resolver.resolving(_curr_ref) as resolved:
# Resolve the resolved schema
local_resolve(resolved, _ref_history + [_curr_ref])
# Remove the reference
del _obj["$ref"]
# Add the resolved fragment to the schema
_obj.update(resolved)
else:
# Loop all properties
for _key, _value in _obj.items():
if isinstance(_value, dict) and "type" in _value:
local_resolve(_value, _ref_history)
else:
local_resolve(_value, _ref_history)
try:
local_resolve(_result, [])
except Exception as e:
raise Exception("schemaTools.resolveSchema: Error resolving schema:" + str(e) + "Schema " + json.dumps(_schema, indent=4))
# Make top allOf into properties
if "allOf" in _result:
_new_properties = {}
for _curr_properties in _result["allOf"]:
_new_properties.update(_curr_properties["properties"])
_result["properties"] = _new_properties
del _result["allOf"]
_result["$schema"] = "http://json-schema.org/draft-04/schema#"
try:
self.mongodb_validator.check_schema(_result)
except Exception as e:
raise Exception("schemaTools.resolveSchema: error validating resolved schema:" + str(e) + "Schema " + json.dumps(_result, indent=4))
return _result
