Python 流水线下一步如何从DB IO接口访问PCollection

我已经使用apache-beam编写了一个小管道，它使用Beam-postgres作为输入连接器，从一个DB表创建一个PCollection. 代码如下所示-

import apache_beam as beam
from apache_beam.options.pipeline_options import PipelineOptions
from psycopg.rows import dict_row
from beam_postgres.io import ReadAllFromPostgres
def __trigger_bill_fetch_job(self):
        print("Triggering bill-fetch job")            
        pipeline = beam.Pipeline()   
       
        read_from_db = ReadAllFromPostgres(
            "host={host} dbname={dbName} user={user} password={password}",
            "SELECT * FROM comparison_bill_data_requests WHERE status='PENDING' AND bill_event_received=true and bill_detail_event_received=true",
            dict_row,
        )

        result = pipeline | "ReadPendingRecordsFromDB" >> read_from_db | "Print result" >> beam.Map(print)

        pipeline.run().wait_until_finish()          
        print("read_from_db done", read_from_db)

IF beam.Map(print)的输出为

{'id': '1', 'bill_id': 'bill-1', 'account_id': None, 'bill_event_received': True, 'bill_detail_event_received': True, 'status': 'PENDING', 'commodity_type': None, 'bill_start_date': datetime.datetime(2023, 12, 6, 11, 52, 28, 78945), 'bill_end_date': datetime.datetime(2023, 12, 6, 11, 52, 28, 78945), 'tenant_id': 'tenant-1', 'created_at': datetime.datetime(2023, 12, 6, 11, 52, 28, 78945), 'updated_at': datetime.datetime(2023, 12, 6, 11, 53, 21, 300224)}

我如何才能将其解析为对象？我想把这个传递到管道中的下一步，并想访问它的属性.我该怎么做呢？