无OAuth 2.0权限下，如何通过GAS导出Google Drive文件？

问题背景 #

我用Google表单收集用户提交的PDF和图片，所有回复都存储在Google表格中。现在需要将这些文件连同其他文本字段一起发送到我的Web服务。我了解可以通过文件ID调用Google Drive API的export接口导出文件，但受公司政策限制，无法创建OAuth 2.0凭据。请问在没有OAuth 2.0权限的情况下，还有哪些方法可以导出Google Drive文件？

当前使用的Google Apps Script代码：

function Main() {

  let arr = new Array()
  let table = SpreadsheetApp.getActiveSpreadsheet().getSheetByName(`Ответы на форму (1)`)
  let count = table.getLastRow()
  let record = table.getRange(count, 2, 1, 16).getValues()

  let email = record[0][0]
  let permission = record [0][1]
  let organization = record[0][2]
  let phone = record[0][3]
  phone = phone.substr(2)
  let target = record[0][6]
  let fullName = record[0][7].trim()
  let gender = record[0][8]
  let inn = record[0][9].toString()
  let snils = record[0][10].toString()
  let passport = record[0][11].toString()
  let issueDate = record[0][12]
  let issueOrganizationId = record[0][13].toString()
  let birthDate = record[0][14].toString()
  let file = record[0][15].replace('https://drive.google.com/open?id=', '').replace('https://drive.google.com/file/d/','').replace('/view?usp=sharing','').trim()

  arr.push(email, organization, phone, target, fullName, gender, inn, snils, passport, issueDate, issueOrganizationId,birthDate, file)
  Logger.log (arr)

  if (record[0][1] == 'Перевыпуск ЭП' && record[0][2] == 'Нет, не менялись') {
    try {
      //API_Renew(organization, email, phone)
    } catch (err) {
      SendEmail(err, email)
    }
  }
  else {
    try {
      //API_New(organization, email, fullName, phone, passport, inn, snils, target, gender, issueDate, issueOrganizationId, birthDate, file)
    } catch (err) {
      SendEmail(err, email)
    }
  }
}


function API_New (organization, email, fullName, phone, passport, inn, snils, target, gender, issueDate, issueOrganizationId, birthDate, file) {

  fullName = fullName.split(' ')

  let payload = [
    {
      "Organization": organization,
      "LastName": fullName[0],
      "FirstName": fullName[1],
      "MiddleName": fullName[2],
      "Email": email,
      "Phone": phone,
      "Series": passport.substring(0, 4),
      "Number": passport.substring(4),
      "Inn": inn,
      "Snils": snils,
      "Target": target, 
      "Gender": gender,
      "IssueDate": issueDate,
      "IssueOrganizationId": issueOrganizationId,
      "BirthDate": birthDate,
      "File": file
    }
  ]

  let options =                                                                                                         
  {
    method: "POST",
    contentType: 'application/json; charset=utf-8',
    payload: JSON.stringify(payload)
  }

  
  return UrlFetchApp.fetch(URL, options)
}

可行解决方案 #

1. 利用Google Apps Script内置DriveApp服务 #

Google Apps Script自带的DriveApp无需额外配置OAuth 2.0凭据，它的权限与脚本绑定（基于当前账号对目标文件的访问权限）。通过文件ID即可直接获取文件的Blob对象，后续可转为Base64编码嵌入JSON payload，或者直接作为附件传输。

代码修改示例：

function API_New (organization, email, fullName, phone, passport, inn, snils, target, gender, issueDate, issueOrganizationId, birthDate, fileId) {
  fullName = fullName.split(' ')
  
  // 通过DriveApp获取文件Blob
  let driveFile = DriveApp.getFileById(fileId);
  let fileBlob = driveFile.getBlob();
  // 将Blob转为Base64编码，适配JSON传输
  let fileBase64 = Utilities.base64Encode(fileBlob.getBytes());

  let payload = [
    {
      "Organization": organization,
      "LastName": fullName[0],
      "FirstName": fullName[1],
      "MiddleName": fullName[2],
      "Email": email,
      "Phone": phone,
      "Series": passport.substring(0, 4),
      "Number": passport.substring(4),
      "Inn": inn,
      "Snils": snils,
      "Target": target, 
      "Gender": gender,
      "IssueDate": issueDate,
      "IssueOrganizationId": issueOrganizationId,
      "BirthDate": birthDate,
      "File": {
        "Id": fileId,
        "Name": driveFile.getName(),
        "MimeType": fileBlob.getContentType(),
        "ContentBase64": fileBase64
      }
    }
  ]

  let options = {
    method: "POST",
    contentType: 'application/json; charset=utf-8',
    payload: JSON.stringify(payload)
  }

  return UrlFetchApp.fetch(URL, options)
}

2. 使用文件公开下载链接 #

若可以调整提交文件的权限（设置为「知道链接的任何人可下载」），可直接构造公开下载链接，通过UrlFetchApp获取文件内容。注意此方法存在隐私风险，需确保文件内容无敏感信息。

代码修改示例：

// 辅助函数：获取公开文件内容
function getPublicFileContent(fileId) {
  const downloadUrl = `https://drive.google.com/uc?export=download&id=${fileId}`;
  const response = UrlFetchApp.fetch(downloadUrl);
  return response.getBlob();
}

// 修改API_New函数
function API_New (organization, email, fullName, phone, passport, inn, snils, target, gender, issueDate, issueOrganizationId, birthDate, fileId) {
  fullName = fullName.split(' ')
  
  // 获取公开文件的Blob并转为Base64
  let fileBlob = getPublicFileContent(fileId);
  let fileBase64 = Utilities.base64Encode(fileBlob.getBytes());

  let payload = [
    {
      "Organization": organization,
      "LastName": fullName[0],
      "FirstName": fullName[1],
      "MiddleName": fullName[2],
      "Email": email,
      "Phone": phone,
      "Series": passport.substring(0, 4),
      "Number": passport.substring(4),
      "Inn": inn,
      "Snils": snils,
      "Target": target, 
      "Gender": gender,
      "IssueDate": issueDate,
      "IssueOrganizationId": issueOrganizationId,
      "BirthDate": birthDate,
      "File": {
        "Id": fileId,
        "Name": fileBlob.getName(),
        "MimeType": fileBlob.getContentType(),
        "ContentBase64": fileBase64
      }
    }
  ]

  let options = {
    method: "POST",
    contentType: 'application/json; charset=utf-8',
    payload: JSON.stringify(payload)
  }

  return UrlFetchApp.fetch(URL, options)
}

注意事项 #

• 使用DriveApp时，需确保脚本关联的账号拥有目标文件的访问权限（表单提交的文件默认会共享给表单/表格所有者，因此一般无需额外设置）。
• 公开链接方式需谨慎使用，避免敏感数据泄露；若文件涉及隐私，优先选择DriveApp方案。
• 大文件（超过10MB）可能触发UrlFetchApp的限制，此时可考虑分块处理，但表单提交的文件通常不会超过此阈值。

内容的提问来源于stack exchange，提问作者Mikhail Gorbov