tornado_rest_queries_book.py

class BookHandler(BaseHandler):

    def initialize(self):
        database_url = os.environ['BOOKS_DB_CONN']
        self.session = queries.TornadoSession(uri=database_url)

    """
    GET handler for fetching numbers from database
    """
    @gen.coroutine
    def get(self, **params):
        try:
            sql = "SELECT row_to_json(json) json FROM (SELECT bookid, title, book_info FROM books WHERE bookid = %(book_id)s) as json;"
            results = yield self.session.query(sql, {'book_id': params['id']})
            data_ret = results.as_dict()
            results.free()
            self.set_status(200)
            self.write({'message': 'Book with id ' + params['id'], 'book': data_ret['json']})
            self.finish()
        except (queries.DataError, queries.IntegrityError) as error:
            print(error)
            self.set_status(500)
            self.write({'message': 'Error: no book with that id exists', 'book': {} })
            self.finish()