Classified the loose functions in metadata.py

metadata.py

@@ -14,20 +14,8 @@ import sqlalchemy.orm
 # TODO: l o g g i n g
 HASH_CHUNK_SIZE = 10485760 # 10mb
 
-db_session = None
-
-_db_session_maker = sqlalchemy.orm.sessionmaker()
-_engine = None
-_configured = False
 _SQLBase = sqlalchemy.ext.declarative.declarative_base()
 
-class MetadataDBSessionException(Exception):
-	'''This exception is raised when something goes wrong with a database session.'''
-
-
-def _uuidgen():
-	return str(uuid.uuid4())
-
 '''
 Metadata ORM classes for SQLAlchemy. For a detailed description of each piece of data, refer to
 metadata/README.md
@@ -112,35 +100,35 @@ class Image(_SQLBase):
 				)
 			)
 
+class hashdb:
+	_engine = None
 
-'''
+	# TODO: db_path's default should be set here, not in frontend.
-# TODO: I was attempting to avoid writing a class to see if I could, but it is not worth the clunk.
+	def __init__(self, db_path):
-Rewrite these functions into a class.
-'''
-
-def configure(db_path):
 		'''
 		Configure and initialize the database for the entire module.
 		Currently, only SQLite is supported.
 
 		db_path: Path for the SQLite database
 		'''
-	_engine = sqlalchemy.create_engine('sqlite:///%s' % db_path)
+		self._engine = sqlalchemy.create_engine('sqlite:///%s' % db_path)
 
-	_SQLBase.metadata.create_all(_engine)
+		_SQLBase.metadata.create_all(self._engine)
-	_db_session_maker.configure(bind=_engine)
+		self._session_maker.configure(bind=self._engine)
-	_configured = True
 
-def search(session, table_object, **constraints):
+	def search(self, table_object, **constraints):
 		'''
 		Search the database for entries matching the given constraints.
 
-	session: SQLAlchemy session, presumably from get_db_session
 		table_object: SQLAlchemy ORM table object, defined in the file above
 		constraints: key-value pairs to match against specific fields in the database
 					Note: Currently, only the query.ilike method is supported. This is intended to
 					eventually support the entire range of available filters.
 		'''
+
+		with self._get_db_session() as session:
+			# TODO: Consider making this return data recursively on items that reference other
+			#	tables.
 			query = session.query(table_object)
 
 			for key, value in constraints.items():
@@ -152,14 +140,20 @@ def search(session, table_object, **constraints):
 
 		return item_list
 
-@contextlib.contextmanager
+	def import_json(self, json_file):
-def get_db_session():
+		'''
+		Import metadata from a json file.
+		'''
+
+		# json files can be large, but not too large for ram
+		# do not exit on invalid metadata, log the error and skip the object
+		pass
+
+	@contextlib.contextmanager
+	def _get_db_session():
 		'''Get a SQLAlchemy database session with a proper context object. '''
-	# TODO: There's probably a more reliable way of knowing whether the database was configured.
-	if not _configured:
-		raise MetadataDBSessionException('Tried to get session without configuring a database.')
 
-	session = _db_session_maker()
+		session = sqlalchemy.orm.sessionmaker()
 		try:
 			yield session