我在这里尝试在导出的Multer GridFS模块中动态更新metadata
属性时有些挣扎。该模块包含一个“上传引擎”,用于处理将文件上传到我的数据库。这是multer-gridfs-storage
库。
这是我的GridFs上传模块gridFs_upload_engine.js
:
> //Upload Engine const mongoose = require('mongoose'); const path =
> require('path'); const crypto = require('crypto'); const multer =
> require('multer'); const GridFsStorage =
> require('multer-gridfs-storage'); const Grid =
> require('gridfs-stream');
>
> //Init Upload Engine let gfs; const database = mongoose.connection;
> const mongoDb = process.env.MONGODB_URI || process.env.MLAB_URL;
>
> database.once('open', () => { //Init Stream gfs =
> Grid(database.db, mongoose.mongo); gfs.collection('uploads'); });
>
> //Create Storage Engine const storage = new GridFsStorage({ url:
> mongoDb, file: (req, file) => {
> return new Promise((resolve, reject) => {
> crypto.randomBytes(16, (err, buf) => {
> if (err) {
> return reject(err);
> }
> const filename = buf.toString('hex') + path.extname(file.originalname);
> const fileInfo = {
> filename: filename,
> bucketName: 'uploads',
> metadata: 'Add Metadata here'
> };
> resolve(fileInfo);
> });
> }); } });
>
> const uploadEngine = multer({ storage });
>
> module.exports = { engine: uploadEngine, gfs };
上面的
metadata
属性是我需要更改的。 fileinfo
对象在上传时由GridFs
添加到每个文件。我以为我可以在req
参数中访问调用此中间件的路由的req.body
,但它以undefined
的形式返回。这是我的测试路线:
const express = require('express');
const router = express.Router();
//Controllers
const upload_controller = require('../../controllers/uploader');
//Dependencies
const upload = require('../../utils/gridFs_upload_engine');
const { engine } = upload;
//Upload Single File
router.post(
'/single',
engine.single('file'),
upload_controller.upload_single_file
);
这是我将
GridFs
中间件传递到我的API路由中的位置。这使控制器可以利用它。这是我的
upload controller
:exports.upload_single_file = (req, res, next) => {
console.log({ file: req.file });
res.redirect('/');
};
console.log
按预期注销用GridFs
上传引擎上传的文件的信息。我知道我需要以某种方式将参数传递给
gridFs_upload_engine.js
。由于此文件是导出的模块,因此我不确定如何完成此操作。我可以将此代码直接放入我的API控制器中并以这种方式进行处理,但是我希望它是一个可以从其他控制器调用的模块。 最佳答案
最后,我通过公开一个让我更新变量的函数解决了这个问题,然后将该变量用作metadata
值。
API路线:
//Dependencies
const upload = require('../../utils/gridFs_upload_engine');
const { engine, updateMetadata } = upload;
//Upload Single File
router.post(
'/single',
(req, res, next) => {
updateMetadata('xxxxxx'); //Static test value
next();
},
engine.single('file'),
upload_controller.upload_single_file
);
在这里,我添加了一个回调,其中包含上载引擎公开的
updateMetadata()
函数。在这里,我使用公开的metadata
功能设置updateMetadata()
。之后,通过使用next()
,router
移至engine.single('file')
,这实际上是处理文件上传的方式。这是
GridFs
上传引擎://Create Storage Engine
let updatedMetadata;
const updateMetadata = id => {
updatedMetadata = id;
};
const storage = new GridFsStorage({
url: mongoDb,
file: (req, file) => {
return new Promise((resolve, reject) => {
crypto.randomBytes(16, (err, buf) => {
if (err) {
return reject(err);
}
const filename = buf.toString('hex') + path.extname(file.originalname);
const fileInfo = {
filename: filename,
bucketName: 'uploads',
metadata: updatedMetadata ? updatedMetadata : null
};
resolve(fileInfo);
});
});
}
});
const uploadEngine = multer({ storage });
module.exports = {
engine: uploadEngine,
updateMetadata,
gfs
};
我不确定这是否是实现此目的的最佳方法,但是它可以正常运行并按预期运行,因此我将不再对此提出质疑。希望这对某人有帮助!
关于javascript - 通过request.body将元数据添加到GridFS文件,我们在Stack Overflow上找到一个类似的问题:https://stackoverflow.com/questions/55693758/