Version: 1.2
Config files example
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This example demonstrates the use of config files to instantiated objects.
class DBConnection:
def connect(self):
...
class MySQLConnection(DBConnection):
def __init__(self, host: str, user: str, password: str) -> None:
self.host = host
self.user = user
self.password = password
def connect(self) -> None:
print(f"MySQL connecting to {self.host}")
class PostgreSQLConnection(DBConnection):
def __init__(self, host: str, user: str, password: str, database: str) -> None:
self.host = host
self.user = user
self.password = password
self.database = database
def connect(self) -> None:
print(f"PostgreSQL connecting to {self.host}")
To support this, we can have a parallel config structure:
conf/
βββ config.yaml
βββ db
βββ mysql.yaml
βββ postgresql.yaml
Config files:
db/mysql.yaml
_target_: my_app.MySQLConnection
host: localhost
user: root
password: 1234
db/postgresql.yaml
_target_: my_app.PostgreSQLConnection
host: localhost
user: root
password: 1234
database: tutorial
config.yaml
defaults:
- db: mysql
With this, you can instantiate the object from the configuration with a single line of code:
@hydra.main(version_base=None, config_path="conf", config_name="config")
def my_app(cfg):
connection = hydra.utils.instantiate(cfg.db)
connection.connect()