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-rw-r--r--app/utils/metadata_parser.py83
1 files changed, 83 insertions, 0 deletions
diff --git a/app/utils/metadata_parser.py b/app/utils/metadata_parser.py
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+++ b/app/utils/metadata_parser.py
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+###############################################################################
+# Copyright (c) 2017 Koren Lev (Cisco Systems), Yaron Yogev (Cisco Systems) #
+# and others #
+# #
+# All rights reserved. This program and the accompanying materials #
+# are made available under the terms of the Apache License, Version 2.0 #
+# which accompanies this distribution, and is available at #
+# http://www.apache.org/licenses/LICENSE-2.0 #
+###############################################################################
+import json
+import os
+from abc import abstractmethod, ABCMeta
+
+from utils.util import get_extension
+
+
+class MetadataParser(metaclass=ABCMeta):
+
+ def __init__(self):
+ super().__init__()
+ self.errors = []
+
+ @abstractmethod
+ def get_required_fields(self) -> list:
+ pass
+
+ def validate_metadata(self, metadata: dict) -> bool:
+ if not isinstance(metadata, dict):
+ raise ValueError('metadata needs to be a valid dict')
+
+ # make sure metadata json contains all fields we need
+ required_fields = self.get_required_fields()
+ if not all([field in metadata for field in required_fields]):
+ raise ValueError("Metadata json should contain "
+ "all the following fields: {}"
+ .format(', '.join(required_fields)))
+ return True
+
+ @staticmethod
+ def _load_json_file(file_path: str):
+ with open(file_path) as data_file:
+ return json.load(data_file)
+
+ def _parse_json_file(self, file_path: str):
+ metadata = self._load_json_file(file_path)
+
+ # validate metadata correctness
+ if not self.validate_metadata(metadata):
+ return None
+
+ return metadata
+
+ @staticmethod
+ def check_metadata_file_ok(file_path: str):
+ extension = get_extension(file_path)
+ if extension != 'json':
+ raise ValueError("Extension '{}' is not supported. "
+ "Please provide a .json metadata file."
+ .format(extension))
+
+ if not os.path.isfile(file_path):
+ raise ValueError("Couldn't load metadata file. "
+ "Path '{}' doesn't exist or is not a file"
+ .format(file_path))
+
+ def parse_metadata_file(self, file_path: str) -> dict:
+ # reset errors in case same parser is used to read multiple inputs
+ self.errors = []
+ self.check_metadata_file_ok(file_path)
+
+ # Try to parse metadata file if it has one of the supported extensions
+ metadata = self._parse_json_file(file_path)
+ self.check_errors()
+ return metadata
+
+ def check_errors(self):
+ if self.errors:
+ raise ValueError("Errors encountered during "
+ "metadata file parsing:\n{}"
+ .format("\n".join(self.errors)))
+
+ def add_error(self, msg):
+ self.errors.append(msg)