db.py

import psycopg2, os
import psycopg2.extras

class Db():
    def __init__(self):
        self._conn_str = os.environ.get('DATABASE_URL')

    def query(self, sql, data=None, verbose=False):
        conn = psycopg2.connect(self._conn_str)
        cur = conn.cursor(cursor_factory = psycopg2.extras.DictCursor)
        if verbose == True:
            print(cur.mogrify(sql, data))
        cur.execute(sql, data)
        conn.commit()

        if cur.description is not None:
            results = cur.fetchall()

        cur.close()
        conn.close()

        if cur.description is not None:
            if len(results) == 1:
                return results[0]
            elif len(results) == 0:
                return None
            else:
                return results




# UNIT TESTS
if __name__=='__main__':
    pass
    #db = Db()
    #users = db.query('select * from participant;')
    #print(users)
    #users = db.query('insert into participant (email) values (%s) returning email;', ['shandgp@clarkson.edu'])
    #print(users)