Python BigQuery Attribute Error : 'Row' Object has no Attribute

Question

我有一个行对象 row.total_bytes_processed，其中包含 return None 的行。如果它 returns None 我有逻辑将值默认为 0

for row in rows:
        if row.total_bytes_processed is  not None:
            cost_dollars = (row.total_bytes_processed/1024 **4) *5
            print( f"JOB_ID : {row.job_id} | Creation_Time : {row.creation_time} |  Query: {row.query} | Total_Bytes_processed : {row.total_bytes_processed} | Estimated_Cost : ${cost_dollars}".format(
            row.job_id, row.creation_time, row.query, row.total_bytes_processed,cost_dollars))
        else:
            row.total_bytes_processed = 0 # <- Error occurs here
            cost_dollars = (int(row.total_bytes_processed) / 1024 ** 4) * 5
            print(f"JOB_ID : {row.job_id} | Creation_Time : {row.creation_time} |  Query: {row.query} | Total_Bytes_processed : {row.total_bytes_processed} | Estimated_Cost : ${cost_dollars}".format(row.job_id, row.creation_time, row.query, row.total_bytes_processed, cost_dollars))

然而，当我这样做时，我收到了这个错误：

row.total_bytes_processed = 0
AttributeError: 'Row' object has no attribute 'total_bytes_processed'

如何修复此错误？我不能将 None(Nonetype) 默认为 0 吗？

我已验证所有行都有 total_bytes_processed。

这是我的源代码：

from google.cloud import bigquery
from google.oauth2 import service_account



sql = """
SELECT
job_id,
creation_time,
user_email,
query,
total_bytes_processed
FROM `region-us`.INFORMATION_SCHEMA.JOBS_BY_PROJECT
WHERE project_id ='nj-dev-blah'
AND creation_time BETWEEN TIMESTAMP_SUB(CURRENT_TIMESTAMP(), INTERVAL 183 DAY)
AND CURRENT_TIMESTAMP()
ORDER BY creation_time DESC
LIMIT 100
"""


query_job = client.query(sql)# Make an API request.
results = query_job.result()
rows = list(results)
print("The query data:")
# print(rows)
for row in rows:
    if row.total_bytes_processed is  not None:
        cost_dollars = (row.total_bytes_processed/1024 **4) *5
        print( f"JOB_ID : {row.job_id} | Creation_Time : {row.creation_time} |  Query: {row.query} | Total_Bytes_processed : {row.total_bytes_processed} | Estimated_Cost : ${cost_dollars}".format(
        row.job_id, row.creation_time, row.query, row.total_bytes_processed,cost_dollars))
    else:
        row.total_bytes_processed = 0
        cost_dollars = (int(row.total_bytes_processed) / 1024 ** 4) * 5
        print(f"JOB_ID : {row.job_id} | Creation_Time : {row.creation_time} |  Query: {row.query} | Total_Bytes_processed : {row.total_bytes_processed} | Estimated_Cost : ${cost_dollars}".format(row.job_id, row.creation_time, row.query, row.total_bytes_processed, cost_dollars))

Answer 1

拥有等于 "None" 的属性与根本没有这样的属性是不同的，如果您使用：

if row.total_bytes_processed is not None:

Python 将尝试访问此对象的名为 "total_bytes_processed" 的属性，然后将其与 None 进行比较。您收到此错误是因为在这种情况下，该对象的属性 "total_bytes_processed" 不存在。

您可以使用方法 "hasattr"，提供您要查找的对象和属性的名称作为参数，如果参数存在，该方法将 return 为真，为假否则：

if hasattr(row, "total_bytes_processed"):

请记住，即使属性存在且等于 "None"，"hasattr" 仍将 return 为真，因此您可以将其作为外部验证，然后在您之后知道该属性存在，验证它是否等于 "None" 并采取相应行动。它会是这样的：

for row in rows:
  if hasattr(row, "total_bytes_processed"):
    if row.total_bytes_processed is not None:
        cost_dollars = (row.total_bytes_processed/1024 **4) *5
        print( f"JOB_ID : {row.job_id} | Creation_Time : {row.creation_time} |  Query: {row.query} | Total_Bytes_processed : {row.total_bytes_processed} | Estimated_Cost : ${cost_dollars}".format(
        row.job_id, row.creation_time, row.query, row.total_bytes_processed,cost_dollars))
    else:
        row.total_bytes_processed = 0
        cost_dollars = (int(row.total_bytes_processed) / 1024 ** 4) * 5
        print(f"JOB_ID : {row.job_id} | Creation_Time : {row.creation_time} |  Query: {row.query} | Total_Bytes_processed : {row.total_bytes_processed} | Estimated_Cost : ${cost_dollars}".format(row.job_id, row.creation_time, row.query, row.total_bytes_processed, cost_dollars))
  else:
    #code for when total_bytes_processed does not exists

Python BigQuery Attribute Error : 'Row' Object has no Attribute

Python BigQuery Attribute Error : 'Row' Object has no Attribute

python

attributes

google-bigquery