egg-multipart

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Use co-busboy to upload file by streaming and
process it without save to disk(using the stream mode).

Just use ctx.multipart() to got file stream, then pass to image processing module such as gm or upload to cloud storage such as oss.

Whitelist of file extensions

For security, if uploading file extension is not in white list, will response as 400 Bad request.

Default Whitelist:

``js
const whitelist = [
// images
'.jpg', '.jpeg', // image/jpeg
'.png', // image/png, image/x-png
'.gif', // image/gif
'.bmp', // image/bmp
'.wbmp', // image/vnd.wap.wbmp
'.webp',
'.tif',
'.psd',
// text
'.svg',
'.js', '.jsx',
'.json',
'.css', '.less',
'.html', '.htm',
'.xml',
// tar
'.zip',
'.gz', '.tgz', '.gzip',
// video
'.mp3',
'.mp4',
'.avi',
];
`

$3

The default fileSize that multipart can accept is 10mb. if you upload a large file, you should specify this config.

`js
// config/config.default.js
exports.multipart = {
fileSize: '50mb',
};
`

$3

Developer can custom additional file extensions:

`js
// config/config.default.js
exports.multipart = {
// will append to whilelist
fileExtensions: [
'.foo',
'.apk',
],
};
`

Can also override built-in whitelist, such as only allow png:

`js
// config/config.default.js
exports.multipart = {
whitelist: [
'.png',
],
};
`

Or by function：

`js
exports.multipart = {
whitelist: (filename) => [ '.png' ].includes(path.extname(filename) || '')
};
`

Note: if define whitelist, then fileExtensions will be ignored.

Examples

More examples please follow:

- Handle multipart request in stream mode
- Handle multipart request in file mode

file mode: the easy way

If you don't know the Node.js Stream work, maybe you should use the file mode to get started.

The usage very similar to bodyParser.

- ctx.request.body: Get all the multipart fields and values, except file.
- ctx.request.files: Contains all file from the multipart request, it's an Array object.

WARNING: you should remove the temporary upload files after you use it,
the async ctx.cleanupRequestFiles() method will be very helpful.

$3

You need to set config.multipart.mode = 'file' to enable file mode:

`js
// config/config.default.js
exports.multipart = {
mode: 'file',
};
`

After file mode enable, egg will remove the old temporary files(don't include today's files) on 04:30 AM every day by default.

`js
config.multipart = {
mode: 'file',
tmpdir: path.join(os.tmpdir(), 'egg-multipart-tmp', appInfo.name),
cleanSchedule: {
// run tmpdir clean job on every day 04:30 am
// cron style see https://github.com/eggjs/egg-schedule#cron-style-scheduling
cron: '0 30 4 *',
disable: false,
},
};
`

Default will use the last field which has same name, if need the all fields value, please set allowArrayField in config.

`js
// config/config.default.js
exports.multipart = {
mode: 'file',
allowArrayField: true,
};
`

$3

`html



title:
file:
Upload



`

Controller which hanlder POST /upload:

`js
// app/controller/upload.js
const Controller = require('egg').Controller;
const fs = require('mz/fs');

module.exports = class extends Controller {
async upload() {
const { ctx } = this;
const file = ctx.request.files[0];
const name = 'egg-multipart-test/' + path.basename(file.filename);
let result;
try {
// process file or upload to cloud storage
result = await ctx.oss.put(name, file.filepath);
} finally {
// remove tmp files and don't block the request's response
// cleanupRequestFiles won't throw error even remove file io error happen
ctx.cleanupRequestFiles();
// remove tmp files before send response
// await ctx.cleanupRequestFiles();
}

ctx.body = {
url: result.url,
// get all field values
requestBody: ctx.request.body,
};
}
};
`

$3

`html



title:
file1:
file2:
Upload



`

Controller which hanlder POST /upload:

`js
// app/controller/upload.js
const Controller = require('egg').Controller;
const fs = require('mz/fs');

module.exports = class extends Controller {
async upload() {
const { ctx } = this;
console.log(ctx.request.body);
console.log('got %d files', ctx.request.files.length);
for (const file of ctx.request.files) {
console.log('field: ' + file.fieldname);
console.log('filename: ' + file.filename);
console.log('encoding: ' + file.encoding);
console.log('mime: ' + file.mime);
console.log('tmp filepath: ' + file.filepath);
let result;
try {
// process file or upload to cloud storage
result = await ctx.oss.put('egg-multipart-test/' + file.filename, file.filepath);
} finally {
// remove tmp files and don't block the request's response
// cleanupRequestFiles won't throw error even remove file io error happen
ctx.cleanupRequestFiles([ file ]);
}
console.log(result);
}
}
};
`

stream mode: the hard way

If you're well-known about know the Node.js Stream work, you should use the stream mode.

$3

`html



title:
file1:
file2:
Upload



`

Controller which hanlder POST /upload:

`js
// app/controller/upload.js
const { Controller } = require('egg');
const fs = require('fs');
const stream = require('stream');
const util = require('util');
const { randomUUID } = require('crypto');
const pipeline = util.promisify(stream.pipeline);

module.exports = class UploadController extends Controller {
async upload() {
const parts = this.ctx.multipart();
const fields = {};
const files = {};

for await (const part of parts) {
if (Array.isArray(part)) {
// fields
console.log('field: ' + part[0]);
console.log('value: ' + part[1]);
} else {
// otherwise, it's a stream
const { filename, fieldname, encoding, mime } = part;

console.log('field: ' + fieldname);
console.log('filename: ' + filename);
console.log('encoding: ' + encoding);
console.log('mime: ' + mime);

// how to handler?
// 1. save to tmpdir with pipeline
// 2. or send to oss
// 3. or just consume it with another for await

// WARNING: You should almost never use the origin filename as it could contain malicious input.
const targetPath = path.join(os.tmpdir(), randomUUID() + path.extname(filename));
await pipeline(part, createWriteStream(targetPath)); // use pipeline not pipe
}
}

this.ctx.body = 'ok';
}
};
`

$3

You can got upload stream by ctx.getFileStream*().

`html



title:
file:
Upload



`

Controller which handler POST /upload:

`js
// app/controller/upload.js
const path = require('node:path');
const { sendToWormhole } = require('stream-wormhole');
const { Controller } = require('egg');

module.exports = class extends Controller {
async upload() {
const { ctx } = this;
// file not exists will response 400 error
const stream = await ctx.getFileStream();
const name = 'egg-multipart-test/' + path.basename(stream.filename);
// process file or upload to cloud storage
const result = await ctx.oss.put(name, stream);

ctx.body = {
url: result.url,
// process form fields by stream.fields
fields: stream.fields,
};
}

async uploadNotRequiredFile() {
const { ctx } = this;
// file not required
const stream = await ctx.getFileStream({ requireFile: false });
let result;
if (stream.filename) {
const name = 'egg-multipart-test/' + path.basename(stream.filename);
// process file or upload to cloud storage
const result = await ctx.oss.put(name, stream);
} else {
// must consume the empty stream
await sendToWormhole(stream);
}

ctx.body = {
url: result && result.url,
// process form fields by stream.fields
fields: stream.fields,
};
}
};
`

$3

`html



title:
file1:
file2:
Upload



`

Controller which hanlder POST /upload:

`js
// app/controller/upload.js
const Controller = require('egg').Controller;

module.exports = class extends Controller {
async upload() {
const { ctx } = this;
const parts = ctx.multipart();
let part;
while ((part = await parts()) != null) {
if (part.length) {
// arrays are busboy fields
console.log('field: ' + part[0]);
console.log('value: ' + part[1]);
console.log('valueTruncated: ' + part[2]);
console.log('fieldnameTruncated: ' + part[3]);
} else {
if (!part.filename) {
// user click upload before choose a file,
// part will be file stream, but part.filename is empty
// must handler this, such as log error.
continue;
}
// otherwise, it's a stream
console.log('field: ' + part.fieldname);
console.log('filename: ' + part.filename);
console.log('encoding: ' + part.encoding);
console.log('mime: ' + part.mime);
const result = await ctx.oss.put('egg-multipart-test/' + part.filename, part);
console.log(result);
}
}
console.log('and we are done parsing the form!');
}
};
`

$3

If the default mode is stream, use the fileModeMatch options to match the request urls switch to file mode.

`js
config.multipart = {
mode: 'stream',
// let POST /upload_file request use the file mode, other requests use the stream mode.
fileModeMatch: /^\/upload_file$/,
// or glob
// fileModeMatch: '/upload_file',
};
`

NOTICE: fileModeMatch options only work on stream` mode.

License

MIT