drop_everything.py

# Given a SQLAlchemy engine, this will drop all the tables reachable from that engine
# I've used this in PostgreSQL, but it should work with other dialects as well.

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

def drop_everything(engine):
    conn = engine.connect()
    trans = conn.begin()
    inspector = reflection.Inspector.from_engine(engine)

    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()