从 busboy 到 MongoDB 的 FileStream

Question

所以我有一个来自 busboy 的传入 FileStream，我想保存到 MongoDB。我想我需要将它作为File 或某种缓冲区来保存它。我确信我可以通过首先使用fs 将其保存到磁盘然后读取它来做到这一点，但这似乎很麻烦。到目前为止，这是我的完整路线代码：

// Upload a new study plan
router.route("/add").post((req, res, next) => {
    let busboy = new Busboy({headers: req.headers});

    // A field was recieved
    busboy.on('field', function (fieldname, val, valTruncated, keyTruncated) {

        if (req.body.hasOwnProperty(fieldname)) { // Handle arrays
            if (Array.isArray(req.body[fieldname])) {
                req.body[fieldname].push(val);
            } else {
                req.body[fieldname] = [req.body[fieldname], val];
            }
        } else { // Else, add field and value to body
            req.body[fieldname] = val;
        }
    });

    // A file was recieved
    busboy.on('file', function (fieldname, file, filename, encoding, mimetype) {
        const saveTo = path.join('.', filename);
        let readFile = null;

        file.on("data", () => {
            console.log("Got file data!");
        })

        file.on("end", () => {
            //How do I save the file to MongoDB?
        })
    });

    // We're done here boys!
    busboy.on('finish', function () {
        //console.log(req.body);
        console.log('Upload complete');
        res.end("That's all folks!");
    });
    return req.pipe(busboy);
});

我想将{"pdf": file} 附加到包含其余数据的req.body...

Answer 1

无需将文件保存到磁盘，您可以使用某种流接口将其直接从 busboy 流式传输到 mongo - 我不确定您希望如何保存文件，但如果这只是一个简单的文件结构我猜你应该使用Mongo's GridFS。

我假设您从某个地方获得了连接和客户端，所以我们将使用它。我们需要来自客户端的 GridFS 存储桶：

const db = client.db(dbName);
const bucket = new mongodb.GridFSBucket(db);

当我们要保存文件时会用到它：

    // A file was recieved
    busboy.on('file', function (fieldname, file, filename, encoding, mimetype) {
        const saveTo = path.join('.', filename);
        // here we PIPE the file to DB.
        file.pipe(bucket.openUploadStream(saveTo));
    });

现在还需要在文件实际保存时做出响应 - 因为这是异步完成的。所以我们需要像这样记录正在运行的操作：

    // place this in the request callback.
    // here's our counter - we'll increment it for each operation started.
    let ops = 0;
    const dec = () => --ops || res.end("That's all folks!");

现在我们稍微修改一下上面的代码，这样在文件保存到 Mongo 之前我们不会响应：

    // A file was recieved
    busboy.on('file', function (fieldname, file, filename, encoding, mimetype) {
        ops++; // we increment ops for each file saved
        const saveTo = path.join('.', filename);
        // here we PIPE the file to DB (pass the db and collection here).
        file.pipe(bucket.openUploadStream(saveTo))
            .on('finish', dec);
    });

    ops++; // we're waiting for finish of the request also so another increment
    busboy.on('finish', dec);

正如您所见，每次文件上传开始时，我们都会增加操作数，完成后，我们会减少操作数。当ops 到达0 时，|| 运算符将执行res.end 方法。

Answer 2

因此，虽然 Michal 的回答可能没有错，但这不是我所追求的。我终于通过使用Buffer 对象找到了解决方案。这是我的代码：

router.route("/add").post((req, res, next) => {
    let busboy = new Busboy({headers: req.headers});
    let buffers = [];

    // A field was recieved
    busboy.on('field', function (fieldname, val, valTruncated, keyTruncated) {

        if (req.body.hasOwnProperty(fieldname)) { // Handle arrays
            if (Array.isArray(req.body[fieldname])) {
                req.body[fieldname].push(val);
            } else {
                req.body[fieldname] = [req.body[fieldname], val];
            }
        } else { // Else, add field and value to body
            req.body[fieldname] = val;
        }
    });

    // A file was recieved
    busboy.on('file', function (fieldname, file, filename, encoding, mimetype) {

        file.on("data", (data) => {
            buffers.push(data);
        });

        file.on("end", () => {
            req.body[fieldname] = Buffer.concat(buffers);
        });
    });

    // We're done here boys!
    busboy.on('finish', function () {
        console.log(req.body);

        const plan = new StudyPlan(req.body);
        plan.save()
            .then(_ => console.log("YEEAEH!"))
            .catch(err => {console.log(err);});

        res.end();
    });
    return req.pipe(busboy);
});