Version: 1.0

Structured Configs example

Example application

This example demonstrates the use of Structured Configs to instantiated objects.

Example usage

my_app.py
class DBConnection:
def __init__(self, driver: str, host: str, port: int) -> None:
self.driver = driver
self.host = host
self.port = port
def connect(self) -> None:
print(f"{self.driver} connecting to {self.host}")
class MySQLConnection(DBConnection):
def __init__(self, driver: str, host: str, port: int) -> None:
super().__init__(driver=driver, host=host, port=port)
class PostgreSQLConnection(DBConnection):
def __init__(self, driver: str, host: str, port: int, timeout: int) -> None:
super().__init__(driver=driver, host=host, port=port)
self.timeout = timeout
@dataclass
class DBConfig:
driver: str = MISSING
host: str = "localhost"
port: int = 80
@dataclass
class MySQLConfig(DBConfig):
_target_: str = "my_app.MySQLConnection"
driver: str = "MySQL"
port: int = 1234
@dataclass
class PostGreSQLConfig(DBConfig):
_target_: str = "my_app.PostgreSQLConnection"
driver: str = "PostgreSQL"
port: int = 5678
timeout: int = 10
@dataclass
class Config:
defaults: List[Any] = field(default_factory=lambda: [{"db": "mysql"}])
db: DBConfig = MISSING
cs = ConfigStore.instance()
cs.store(name="config", node=Config)
cs.store(group="db", name="mysql", node=MySQLConfig)
cs.store(group="db", name="postgresql", node=PostGreSQLConfig)
@hydra.main(config_name="config")
def my_app(cfg: Config) -> None:
connection = instantiate(cfg.db)
connection.connect()
if __name__ == "__main__":
my_app()

Sample Output

$ python my_app.py
MySQL connecting to localhost:1234
$ python my_app.py db=postgresql
PostgreSQL connecting to localhost:5678
Last updated on by Rosario Scalise