db_create.py

import os
import sys

from sqlalchemy.engine import reflection
from sqlalchemy.schema import (
        MetaData,
        Table,
        DropTable,
        ForeignKeyConstraint,
        DropConstraint,
        )

from scisim import app, db

if not app.config['HEROKU'] and os.path.exists("app.db"):
    os.remove("app.db")

def db_DropEverything(db):
    # From http://www.sqlalchemy.org/trac/wiki/UsageRecipes/DropEverything

    conn=db.engine.connect()

    # the transaction only applies if the DB supports
    # transactional DDL, i.e. Postgresql, MS SQL Server
    trans = conn.begin()

    inspector = reflection.Inspector.from_engine(db.engine)

    # gather all data first before dropping anything.
    # some DBs lock after things have been dropped in 
    # a transaction.
    metadata = MetaData()

    tbs = []
    all_fks = []

    for table_name in inspector.get_table_names():
        fks = []
        for fk in inspector.get_foreign_keys(table_name):
            if not fk['name']:
                continue
            fks.append(
                ForeignKeyConstraint((),(),name=fk['name'])
                )
        t = Table(table_name,metadata,*fks)
        tbs.append(t)
        all_fks.extend(fks)

    for fkc in all_fks:
        conn.execute(DropConstraint(fkc))

    for table in tbs:
        conn.execute(DropTable(table))

    trans.commit()

#db.reflect()
#db.session.commit()
#db.drop_all()

db_DropEverything(db)

db.create_all()



print "Loading simulations..."
sys.path.append("simulations/")
for sim_directory in os.listdir("simulations"):
    print "    %s" % sim_directory
    __import__(sim_directory)

    print "        done"