I am trying out SQLAlchemy and I am using this connection string:
engine = create_engine('sqlite:///C:\\sqlitedbs\\database.db')
Does SQLAlchemy create an SQLite database if one is not already present in a directory it was supposed to fetch the database file?
Yes,sqlalchemy does create a database for you.I confirmed it on windows using this code.
Be aware DB creation is lazy - it is created at the latest possible time. In this example this is when the metadata is created (and thus tries to create the tables).
from sqlalchemy import create_engine, ForeignKey
from sqlalchemy import Column, Date, Integer, String
from sqlalchemy.ext.declarative import declarative_base
engine = create_engine('sqlite:///C:\\sqlitedbs\\school.db', echo=True)
Base = declarative_base()
class School(Base):
__tablename__ = "woot"
id = Column(Integer, primary_key=True)
name = Column(String)
def __init__(self, name):
self.name = name
# this ultimately creates the database (if it does not exist)
Base.metadata.create_all(engine)
create_all(engine) statement, not during the create_engine(...) statement.As others have posted, SQLAlchemy will do this automatically. I encountered this error, however, when I didn't use enough slashes!
I used SQLALCHEMY_DATABASE_URI="sqlite:///path/to/file.db" when I should have used four slashes: SQLALCHEMY_DATABASE_URI="sqlite:////path/to/file.db"
Linux stored SQLite3 database
database will be create in the same folder as the .py file:
engine = create_engine('sqlite:///school.db', echo=True)
will instantiate the school.db file in the same folder as the .py file.
I found (using sqlite+pysqlite) that if the directory exists, it will create it, but if the directory does not exist it throws an exception:
OperationalError: (sqlite3.OperationalError) unable to open database file
My workaround is to do this, although it feels nasty:
if connection_string.startswith('sqlite'):
db_file = re.sub("sqlite.*:///", "", connection_string)
os.makedirs(os.path.dirname(db_file), exist_ok=True)
self.engine = sqlalchemy.create_engine(connection_string)
@Gandolf's answer was good.
The database is created it when you make any connection with your engine.
Here's an example of doing nothing with a database besides connecting to it, and this will create the database.
from sqlalchemy import create_engine
engine = create_engine('sqlite:///database.db')
with engine.connect() as conn:
pass
Without the engine.connect() or some form of metadata.create_all() the database will not be created.
