Google Cloud Functions - 电子邮件脚本 - CORS 错误答案

【问题标题】：Google Cloud Functions - e-mail script - CORS errorGoogle Cloud Functions - 电子邮件脚本 - CORS 错误
【发布时间】：2020-06-17 09:26:27
【问题描述】：

我正在制作一个通过 POST 请求接收数据并发送包含该数据的电子邮件的函数。当我尝试从不同的域调用我的函数时，出现以下错误：

CORS 策略已阻止从源“chrome-search://local-ntp”访问“我的函数”处的 XMLHttpRequest：请求的资源上不存在“Access-Control-Allow-Origin”标头。

我按照云文档上的说明在我的代码顶部添加了以下内容：

headers = {
    'Access-Control-Allow-Origin': '*',
    'Access-Control-Allow-Methods': '*',
    'Access-Control-Allow-Headers': 'Authorization',
    'Access-Control-Max-Age': '3600',
    'Access-Control-Allow-Credentials': 'true'
}
return ('', 204, headers)

错误已解决，但我的其余代码在 return 语句之后没有运行。如何插入标题然后继续运行我的脚本？

整个代码如下：

import smtplib
from email.mime.text import MIMEText
from email.mime.multipart import MIMEMultipart
from email.mime.image import MIMEImage
from google.cloud import storage
import requests

def teste_email(request):

    headers = {
            'Access-Control-Allow-Origin': '*',
            'Access-Control-Allow-Methods': '*',
            'Access-Control-Allow-Headers': 'Authorization',
            'Access-Control-Max-Age': '3600',
            'Access-Control-Allow-Credentials': 'true'
    }
    return ('', 204, headers)


    # Pega as variáveis passadas no request
    request_json = request.get_json()
    nome_projeto = request_json['nome_projeto']
    logo_ic = request_json['logo_ic']
    logo_aplicacao = request_json['logo_aplicacao']
    title = request_json['title']
    link = request_json['link']
    descricao = request_json['descricao']
    base = request_json['base']

    # Lê o arquivo do template armazenado no cloud storage e o atribui a uma variável
    client = storage.Client()
    bucket = client.get_bucket('templates_email_icherry')
    blob = bucket.get_blob("template-1.txt")
    downloaded_blob = blob.download_as_string()
    template = downloaded_blob.decode("utf-8")

    # Substitui as variáveis no template pelos valores passados na chamada
    template = template.replace("{title}", title)
    template = template.replace("{logo_ic}", logo_ic)
    template = template.replace("{logo_aplicacao}", logo_aplicacao)
    template = template.replace("{descricao}", descricao)
    template = template.replace("{link}", link)
    template = template.replace("{nome_projeto}", nome_projeto)
    template = template.replace("{base}", base)

    # Variáveis para o envio do e-mail
    email = 'email'
    password = 'password'
    send_to_email = 'email'
    subject = 'Assunto do email'
    messagePlain = 'Message Plain'

    msg = MIMEMultipart('alternative')
    msg['From'] = email
    msg['To'] = send_to_email
    msg['Subject'] = subject

    msg.attach(MIMEText (messagePlain, 'plain'))
    msg.attach(MIMEText (template, 'html'))

    server = smtplib.SMTP('smtp.gmail.com', 587)
    server.starttls()
    server.login(email, password)
    text = msg.as_string()
    server.sendmail(email, send_to_email, text)
    server.quit()

【问题讨论】：

return 在其他代码执行之后，而不是之前。
我也试过了，还是一样的错误
我可以使错误消失的唯一方法是使用这样的代码
如果没有minimal reproducible example，这个问题将很难帮助您
我编辑了问题，所以代码更详细

标签： python http post google-cloud-functions

【解决方案1】：

在您的代码中，您必须将return 语句放在调用的末尾。这是因为 return 是停止当前函数调用的执行并返回相关值的指令。

因此，如果您希望代码执行并返回 CORS 标头，则它必须是函数的最后一次调用。这是生成的代码：

import smtplib
from email.mime.text import MIMEText
from email.mime.multipart import MIMEMultipart
from email.mime.image import MIMEImage
from google.cloud import storage
import requests

def teste_email(request):

    # Pega as variáveis passadas no request
    request_json = request.get_json()
    nome_projeto = request_json['nome_projeto']
    logo_ic = request_json['logo_ic']
    logo_aplicacao = request_json['logo_aplicacao']
    title = request_json['title']
    link = request_json['link']
    descricao = request_json['descricao']
    base = request_json['base']

    # Lê o arquivo do template armazenado no cloud storage e o atribui a uma variável
    client = storage.Client()
    bucket = client.get_bucket('templates_email_icherry')
    blob = bucket.get_blob("template-1.txt")
    downloaded_blob = blob.download_as_string()
    template = downloaded_blob.decode("utf-8")

    # Substitui as variáveis no template pelos valores passados na chamada
    template = template.replace("{title}", title)
    template = template.replace("{logo_ic}", logo_ic)
    template = template.replace("{logo_aplicacao}", logo_aplicacao)
    template = template.replace("{descricao}", descricao)
    template = template.replace("{link}", link)
    template = template.replace("{nome_projeto}", nome_projeto)
    template = template.replace("{base}", base)

    # Variáveis para o envio do e-mail
    email = 'email'
    password = 'password'
    send_to_email = 'email'
    subject = 'Assunto do email'
    messagePlain = 'Message Plain'

    msg = MIMEMultipart('alternative')
    msg['From'] = email
    msg['To'] = send_to_email
    msg['Subject'] = subject

    msg.attach(MIMEText (messagePlain, 'plain'))
    msg.attach(MIMEText (template, 'html'))

    server = smtplib.SMTP('smtp.gmail.com', 587)
    server.starttls()
    server.login(email, password)
    text = msg.as_string()
    server.sendmail(email, send_to_email, text)
    server.quit()

    headers = {
        'Access-Control-Allow-Origin': '*',
        'Access-Control-Allow-Methods': '*',
        'Access-Control-Allow-Headers': 'Authorization',
        'Access-Control-Max-Age': '3600',
        'Access-Control-Allow-Credentials': 'true'
    }
    return ('', 204, headers)

【讨论】：