Question

我想从MongoDB GridFs中读取文件，并将其附加到从节点邮件程序发送的邮件中。因此，我需要在服务器端读取此文件，这意味着我无权访问http请求或响应对象，并且无法通过管道将读取的流传递给Internet上多个位置建议的响应。

我读取文件并作为缓冲区发送的代码如下-

let _fetchFileById = async (fileId, options) => {
  let db = options.db
    , gfs = Grid(db, mongo)
    , filename = fileId
    , file_buf = new Buffer('buffer');
  return new Promise((resolve,reject) => {
    gfs.collection('jobdescription')

    let readstream = gfs.createReadStream({
      filename: filename
      , root: 'jobdescription'
    })

    readstream.on('data', function (chunk) {
      console.log("writing!!!");
      // file_buf.push(chunk)
      if (!file_buf)
      file_buf = chunk;
      else file_buf = Buffer.concat([file_buf, chunk]);
    });
    readstream.on('end', function () {
      // var buffer = Buffer.concat(file_buf);
      db.close();
      console.log(`returning`)
      // console.log(file_buf)
      resolve(file_buf)
    })
  })
}

当我将file_buf用作节点邮件程序中附件的输入时，我得到了以下错误-

TypeError [ERR_INVALID_ARG_TYPE]: The "chunk" argument must be one of type string or Buffer. Received type object。任何帮助或指针将不胜感激。

Answer 1

最后，我没有找到一种方法来读取文件并直接从方法中返回它，但是我做了一个小的解决方法，即从db中读取文件并将其临时存储在本地目录中，一旦我将其附加到nodemailer上，我打算将其删除。我在这里发布方法，以防万一它有用-

exports.downloadFile = async (req, fileName) => {
  let db = req.headers.options.db
    , gridfs = Grid(db, mongo)

  gridfs.collection('jobdescription')
  if (gridfs) {
    let fsstreamwrite = fs.createWriteStream(
      path.join(process.cwd(), `./app/jobdescriptions/${fileName}`)
    )
    let readstream = gridfs.createReadStream({
      filename: fileName
    })
    readstream.pipe(fsstreamwrite);
    return readstream.on("close", file => {
      console.log("File Read successfully from database");
      return file;
    })
  } else {
    console.log("Sorry No Grid FS Object");
  }
}

在NodeJS应用程序的服务器端从MongoDB GridFS读取文件

1 个答案: