如何在Microsoft Graph API请求体中动态发送附件？附报错排查

问题现象 #

• 调用Graph API时返回RequestBodyRead错误：

  {"error":{"code":"RequestBodyRead","message":"An unexpected 'StartObject' node was found for property named 'name' when reading from the JSON reader. A 'PrimitiveValue' node was expected."}}
  

• 请求体中附件部分的name和contentType字段为空对象：

  "attachments":[{"@odata.type":"#microsoft.graph.fileAttachment","name":{},"contentType":{},"contentBytes":"SGVsbG8gV29ybGQh"}],"saveToSentItems":"true"}
  

问题根源 #

1. 变量未正确初始化：name和type仅在GlideRecord循环中赋值，若没有匹配的附件，变量会保留未定义状态，ServiceNow中直接引用GlideRecord字段会返回GlideElement对象，JSON序列化后变为{}
2. 附件逻辑缺陷：当前代码仅保留最后一个附件，未处理多附件场景
3. 附件内容错误：使用固定字符串作为contentBytes，未实际读取附件的二进制内容并Base64编码

修正方案 #

解决步骤 #

• 初始化变量为空字符串，避免未赋值时出现对象
• 循环构建附件数组，支持多个附件
• 使用GlideSysAttachment.getContentBase64()获取真实的附件Base64内容
• 添加无附件时的判断，避免发送空附件节点

修正后的完整代码 #

var body = current.body_text;
var subject = current.subject;

// 初始化附件数组，避免无附件时出现异常
var attachments = [];
var att = new GlideRecord('sys_attachment');
att.addQuery('table_name', 'sys_email');
att.addQuery('table_sys_id', current.sys_id);
att.query();

// 循环处理所有匹配的附件
while(att.next()) {
    gs.info('Processing attachment: ' + att.file_name);
    // 显式转为字符串，避免返回GlideElement对象
    var fileName = att.file_name.toString();
    var contentType = att.content_type.toString();
    // 获取附件的Base64编码内容
    var contentBase64 = GlideSysAttachment.getContentBase64(att);

    attachments.push({
        "@odata.type": "#microsoft.graph.fileAttachment",
        "name": fileName,
        "contentType": contentType,
        "contentBytes": contentBase64
    });
}

var restMessage = new sn_ws.RESTMessageV2('Email PoC', 'POST Email User');
restMessage.setStringParameter('id', current.u_emailbox_id);

// 处理CC收件人逻辑
var ccAddresses = current.getValue('copied');
var ccRecipients = [];
if (ccAddresses) {
    var ccList = ccAddresses.replace(/\s*,\s*/g, ',').split(',');
    for (var i = 0; i < ccList.length; i++) {
        ccRecipients.push({
            "emailAddress": {
                "address": ccList[i].trim()
            }
        });
    }
}

// 构建请求体基础结构
var requestBody = {
    "message": {
        "subject": current.getValue('subject'),
        "body": {
            "contentType": "html",
            "content": current.getValue('body')
        },
        "toRecipients": [{
            "emailAddress": {
                "address": current.getValue('direct')
            }
        }],
        "internetMessageHeaders": [{
            "name": "X-MSIP-APP-classification",
            "value": "Restricted"
        }]
    },
    "saveToSentItems": "true"
};

// 仅当存在附件时，添加attachments节点
if (attachments.length > 0) {
    requestBody.message.attachments = attachments;
}

// 发送请求并记录日志
gs.info('Final Request Body: ' + JSON.stringify(requestBody));
restMessage.setRequestBody(JSON.stringify(requestBody));
var response = restMessage.execute();

var responseBody = response.getBody();
var httpStatus = response.getStatusCode();

gs.info('API Response Body: ' + responseBody);
gs.info('HTTP Status Code: ' + httpStatus);

关键说明 #

• 所有GlideRecord字段调用.toString()确保获取字符串值，彻底避免返回GlideElement对象
• 使用GlideSysAttachment.getContentBase64()直接获取附件的Base64编码内容，无需手动处理二进制数据
• 仅当存在附件时才添加attachments节点，避免发送空数组或无效对象
• 优化CC收件人处理逻辑，增加trim()清除邮箱地址前后空格

内容的提问来源于stack exchange，提问作者Brijmohan