如何在数据流管道中修复"AttributeError：'str‘对象没有属性'items'“从PubSub读取并写入BigQuery

import json
from apache_beam import Pipeline, ReadFromPubSub, WriteToBigQuery
from apache_beam.options.pipeline_options import PipelineOptions

class ParseMessage(beam.DoFn):
    def process(self, element):
        try:
            # 将JSON字符串解析为字典对象
            record = json.loads(element.decode('utf-8'))
            yield record
        except json.JSONDecodeError as e:
            # 处理解析失败的情况
            print(f"Failed to parse JSON: {e}")
            yield None

def run():
    options = PipelineOptions()
    
    with Pipeline(options=options) as p:
        (p
         | 'Read from PubSub' >> ReadFromPubSub(topic='your-pubsub-topic')
         | 'Parse JSON' >> beam.ParDo(ParseMessage())
         | 'Filter valid records' >> beam.Filter(lambda x: x is not None)
         | 'Write to BigQuery' >> WriteToBigQuery(
               table='your-project-id:your_dataset.your_table',
               schema='your_schema',
               write_disposition=beam.io.BigQueryDisposition.WRITE_APPEND,
               create_disposition=beam.io.BigQueryDisposition.CREATE_IF_NEEDED))

if __name__ == '__main__':
    run()