how to search for the existence of a database with sqlalchemy

Question

I need to write a script with python sqlalchemy that searchs if a database exist, if the database exists it should query the database else create database and tables.

Pseudocode:

   if db exists cursor.execute(sql)    else       create db test;       create tables;       insert data; 

Answer 1

You can use the sqlalchemy.engine.base.Engine.connect() method, which will raise a OperationalError if the database does not exist.

import sqlalchemy as sqla from sqlalchemy import create_engine from sqlalchemy.exc import OperationalError db = sqla.create_engine(database_uri) try:     db.connect()     db.execute(sql) except OperationalError:     # Switch database component of the uri     default_database_uri = os.path.join(os.path.dirname(                            str(db.engine.url)), 'mysql')     db = sqla.create_engine(default_database_uri)     # Create your missing database/tables/data here     # ... 

Answer 2

An alternate way if you don't mind to import other libs is to use sqlalchemy_utils. Then database_exists does what you expect, which you may pass the sqlalchemy database uri.

if database_exists('sqllite:////tmp/test.db'):     do_stuff_with_db(db) 

http://sqlalchemy-utils.readthedocs.org/en/latest/database_helpers.html