如何从 Google BigQuery 行迭代器对象返回字符串？

Question

我的任务是编写一个 Python 脚本，可以从 BigQuery 获取结果并将其通过电子邮件发送出去。我已经编写了可以成功发送电子邮件的代码，但在将 BigQuery 脚本的结果包含在实际电子邮件中时遇到问题。查询结果是正确的，但我从查询（结果）返回的实际对象始终以 Nonetype 形式返回。

例如，电子邮件应如下所示：

你好，

您有以下已“开放”超过 7 天的问题：

-在此处列出来自 bigquery 代码的问题

谢谢。

该代码从contacts.txt 文件中读取联系人，并从message.txt 文件中读取电子邮件模板。我尝试将bigquery对象变成字符串，但仍然会导致错误。

from google.cloud import bigquery
import warnings
warnings.filterwarnings("ignore", "Your application has authenticated using end user credentials")
from email.mime.multipart import MIMEMultipart
from email.mime.text import MIMEText
from string import Template


def query_emailtest():
    client = bigquery.Client(project=("analytics-merch-svcs-thd"))
    query_job = client.query("""
       select dept, project_name, reset, tier, project_status, IssueStatus, division, store_number, top_category,
       DATE_DIFF(CURRENT_DATE(), in_review, DAY) as days_in_review
       from `analytics-merch-svcs-thd.MPC.RESET_DETAILS`
       where in_review IS NOT NULL
       AND IssueStatus = "In Review"
       AND DATE_DIFF(CURRENT_DATE(), in_review, DAY) > 7
       AND ready_for_execution IS NULL
       AND project_status = "Active"
       AND program_name <> "Capital" 
       AND program_name <> "SSI - Capital"
       LIMIT 50
    """)
    results = query_job.result()  # Waits for job to complete. 
    return results #THIS IS A NONETYPE


def get_queryresults(results):   #created new method to put query results into a for loop and store it in a variable
    for i,row in enumerate(results,1):
        bq_data = (i , '. ' + str(row.dept) + " " + row.project_name + ", Reset #: " + str(row.reset) + ", Store #: " + str(row.store_number) + ", " + row.IssueStatus + " for " + str(row.days_in_review)+ " days")
        print (bq_data)

def get_contacts(filename):
    names = []
    emails = []
    with open(filename, mode='r', encoding='utf-8') as contacts_file:
        for a_contact in contacts_file:
            names.append(a_contact.split()[0])
            emails.append(a_contact.split()[1])
    return names, emails

def read_template(filename):
    with open(filename, 'r', encoding='utf-8') as template_file:
        template_file_content = template_file.read()
    return Template(template_file_content)


names, emails = get_contacts('mycontacts.txt')  # read contacts
message_template = read_template('message.txt')
results = query_emailtest()

bq_results = get_queryresults(query_emailtest())


import smtplib
# set up the SMTP server
s = smtplib.SMTP(host='smtp-mail.outlook.com', port=587)
s.starttls()
s.login('email', 'password')


   # For each contact, send the email:
for name, email in zip(names, emails):
    msg = MIMEMultipart()       # create a message

   # bq_data = get_queryresults(query_emailtest()) 

    # add in the actual person name to the message template
    message = message_template.substitute(PERSON_NAME=name.title())
    message = message_template.substitute(QUERY_RESULTS=bq_results) #SUBSTITUTE QUERY RESULTS IN MESSAGE TEMPLATE. This is where I am having trouble because the Row Iterator object results in Nonetype. 


    # setup the parameters of the message
    msg['From']='email'
    msg['To']='email'
    msg['Subject']="This is TEST"
  #  body = str(get_queryresults(query_emailtest())) #get query results from method to put into message body 


    # add in the message body
   # body = MIMEText(body)
    #msg.attach(body)
    msg.attach(MIMEText(message, 'plain'))


  #  query_emailtest() 
  #  get_queryresults(query_emailtest())


    # send the message via the server set up earlier.
    s.send_message(msg)

    del msg 

留言模板：

亲爱的${PERSON_NAME}，

希望你一切顺利。请查找以下针对已“审核”超过 7 天的问题的警报。

${QUERY_RESULTS}

如果您想了解更多信息，请访问此链接，其中包含警报的完整仪表板视图。

ISE 服务

Answer 1

BQresult()函数返回一个生成器，所以我认为您需要将您的更改return为yield from.

我距离 python 专家还很远，但是下面的精简代码对我有用。

from google.cloud import bigquery
import warnings
warnings.filterwarnings("ignore", "Your application has authenticated using end user credentials")

def query_emailtest():
    client = bigquery.Client(project=("my_project"))
    query_job = client.query("""
       select field1, field2 from `my_dataset.my_table` limit 5
    """)
    results = query_job.result()  
    yield from results # NOTE THE CHANGE HERE

results = query_emailtest()

for row in results:
    print(row.field1, row.field2)