如何解决Python中hourmailer发送附件的JSON序列化错误？

在项目中使用hourmailer发送带附件（如txt文件）的邮件时，执行response = requests.request("POST", url, json=payload, headers=headers)出现错误Object of type bytes is not JSON serializable，原因是attachment.read()读取的字节流无法被JSON序列化。原代码如下：

import requests

url = "https://hourmailer.p.rapidapi.com/send"

subject = str(input("Enter a subject:"))
email_origin = str(input("Enter a Origin email:"))
email_html_file = str(input("Enter the HTML file name:"))
  
# open the file to be sent 
filename = "{email}".format(email=email_html_file)
attachment = open("C:\PythonItems\Email\{email}".format(email=email_html_file), "rb")


payload = {
    # "toAddress": "nellyordona@gmail.com",
    "fromAddress":email_origin,
    "toAddress": "jumo.vicentillo.sjc@phinmaed.com",
    "title": subject,
    "message": "Hi, I'm from {email}".format(email=email_origin),
    "attachment":attachment.read()

}

headers = {
    "content-type": "application/json",
    "X-RapidAPI-Key": "............",
    "X-RapidAPI-Host": "hourmailer.p.rapidapi.com"
}


response = requests.request("POST", url, json=payload, headers=headers)

split = response.text.split(":")[1][:-1]
if (split == '"Message sent to {text}"'.format(text="jumo.vicentillo.sjc@phinmaed.com")):
    print("Message sent to {text}".format(text="jumo.vicentillo.sjc@phinmaed.com!\n"))
    print("All messages sent!")

JSON无法直接序列化字节流，核心解决思路是将附件内容转换为可被JSON序列化的格式，或改用适合传输文件的请求格式，以下两种方案可选：

方案一：将附件编码为Base64字符串（适配JSON请求） #

把字节流转换为Base64编码的字符串，这是文本格式，可被JSON正常序列化。同时注意用with open自动管理文件句柄，避免资源泄漏：

import requests
import base64

url = "https://hourmailer.p.rapidapi.com/send"

subject = input("Enter a subject:")
email_origin = input("Enter a Origin email:")
email_html_file = input("Enter the HTML file name:")

# 读取文件并编码为Base64字符串
file_path = f"C:\\PythonItems\\Email\\{email_html_file}"
with open(file_path, "rb") as attachment:
    attachment_base64 = base64.b64encode(attachment.read()).decode('utf-8')

payload = {
    "fromAddress": email_origin,
    "toAddress": "jumo.vicentillo.sjc@phinmaed.com",
    "title": subject,
    "message": f"Hi, I'm from {email_origin}",
    "attachment": attachment_base64,
    "attachmentName": email_html_file  # 多数邮件API需指定附件文件名，需匹配hourmailer文档参数名
}

headers = {
    "X-RapidAPI-Key": "............",
    "X-RapidAPI-Host": "hourmailer.p.rapidapi.com"
}

try:
    response = requests.post(url, json=payload, headers=headers)
    response.raise_for_status()  # 主动抛出HTTP请求错误
    
    if f'"Message sent to jumo.vicentillo.sjc@phinmaed.com"' in response.text:
        print("Message sent to jumo.vicentillo.sjc@phinmaed.com!\n")
        print("All messages sent!")
    else:
        print(f"发送失败，响应内容：{response.text}")
except Exception as e:
    print(f"请求出错：{str(e)}")

方案二：改用multipart/form-data格式提交（更适合文件传输） #

如果hourmailer API支持表单形式接收附件，直接用requests的files参数提交，无需编码转换：

import requests

url = "https://hourmailer.p.rapidapi.com/send"

subject = input("Enter a subject:")
email_origin = input("Enter a Origin email:")
email_html_file = input("Enter the HTML file name:")

file_path = f"C:\\PythonItems\\Email\\{email_html_file}"

payload = {
    "fromAddress": email_origin,
    "toAddress": "jumo.vicentillo.sjc@phinmaed.com",
    "title": subject,
    "message": f"Hi, I'm from {email_origin}"
}

files = {
    "attachment": open(file_path, "rb")
}

headers = {
    "X-RapidAPI-Key": "............",
    "X-RapidAPI-Host": "hourmailer.p.rapidapi.com"
}

try:
    response = requests.post(url, data=payload, files=files, headers=headers)
    response.raise_for_status()
    
    if f'"Message sent to jumo.vicentillo.sjc@phinmaed.com"' in response.text:
        print("Message sent to jumo.vicentillo.sjc@phinmaed.com!\n")
        print("All messages sent!")
    else:
        print(f"发送失败，响应内容：{response.text}")
except Exception as e:
    print(f"请求出错：{str(e)}")
finally:
    files["attachment"].close()

内容的提问来源于stack exchange，提问作者Myth Vince