BigQuery字段的类型已从“ STRING”更改为“ TIMESTAMP”

问题描述

我正在使用Python API将数据导入BigQuery：

import os
from google.cloud import bigquery
from google.cloud.exceptions import BadRequest
import json

from schema import schema


target_project_name = 'project_name'
target_dataset_name = 'dataset_name'
target_table_name = 'table_name'

os.environ["GOOGLE_APPLICATION_CREDENTIALS"] = './credentials.json'

dataset_ref = bigquery.dataset.DatasetReference(target_project_name,target_dataset_name)
table_ref = bigquery.table.TableReference(dataset_ref,target_table_name)

job_config = bigquery.LoadJobConfig()
job_config.schema = schema

client = bigquery.Client()

cnt = 0

with open('./data/transformed_v2.json','r') as f:
    json_list = []
    for line in f.readlines():
        cnt += 1
        if cnt >= 10:
            break
        json_contents = json.loads(line)
        json_list.append(json_contents)


    job = client.load_table_from_json(json_list,table_ref)

try:
    result = job.result()
except BadRequest as ex:
    for err in ex.errors:
        print(err)
    print(job.errors)

上面的代码中提到的schema包含一个有问题的字段migration_datetime，该字段定义为bigquery.SchemaField("migration_datetime","STRING",mode="NULLABLE")。该字段包含存储在'%Y-%m-%dT%H:%M:%s' format. The schema in the target table has the migration_datetime field specified as STRING`中的值。

job.result()引发错误，提示Field migration_datetime has changed type from STRING to TIMESTAMP。为了减轻这种情况，我在_string列的值中添加了migration_datetime后缀，但仍然发生错误。你可能是什么原因？

解决方法

请考虑将job_config像here一样传递到load_table_from_json或使用client.schema_from_json