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{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Variable 'dsn' needs to be initialized in create_database(). Otherwise 'UnboundLocalError: cannot access local variable' possible if 'database' arg. points to an ALIAS","articleBody":"Please consider func create_database(). \n\nThere is following code starting from line 2400:\n```\n    db_config: DatabaseConfig = driver_config.get_database(database)\n    if db_config is None:\n        db_config = driver_config.db_defaults\n        srv_config = driver_config.server_defaults\n        if _is_dsn(database):\n            dsn = database\n            database = None\n            srv_config.host.clear()\n    else:\n         . . .\n```\n\nIf control falls into the branch \"if db_config is None\" and then into \"if _is_dsn(database)\" -- all fine.\nBut if ```_is_dsn(database)``` returns False then we have a problem: ```dsn``` remains undefined until following call at line 2435:\n```\n    dsn = _connect_helper(dsn, srv_config.host.value, srv_config.port.value,\n                          database, db_config.protocol.value)\n```\nThis code will raise \"UnboundLocalError: cannot access local variable 'dsn' where it is not associated with a value\"\n\nFunction ```_is_dsn()``` may return False if value of ```database``` argument represents an ALIAS rather than file (e.g. ```db_main_alias``` used in replication tests or similar strings).\n\n\nThis is what i propose:\n```\nComparing files core.py and core-upd.py\n***** core.py\n 2401:      if db_config is None:\n 2402:          db_config = driver_config.db_defaults\n***** core-upd.py\n 2402:      # pzotov, 11.09.2025: we have to initialize here 'dsn' variable otherwise we get error\n 2403:      # UnboundLocalError: cannot access local variable 'dsn' where it is not associated with a value\n 2404:      # if the 'database' argument is an ALIAS, e.g. 'db_main_alias' etc!\n 2405:      dsn: str | None = None\n 2407:      if db_config is None:\n 2408:          db_config = driver_config.db_defaults\n*****\n```","author":{"url":"https://github.com/pavel-zotov","@type":"Person","name":"pavel-zotov"},"datePublished":"2025-09-11T16:28:14.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":0},"url":"https://github.com/56/python3-driver/issues/56"}