Javascript 如何使用 Koa 解析多部分/表单数据体？

How to parse multipart/form-data body with Koa?

提问by eightyfive

Because I spent some (too much) time figuring out this simple requirement. I am documenting here the way to achieve multipart/form-databody parsing with Koa.

因为我花了一些（太多）时间来弄清楚这个简单的要求。我在这里记录了multipart/form-data使用 Koa实现body 解析的方法。

In my case, the reason of the confusion was the number of alternatives available out there:

就我而言，混淆的原因是可用的替代品数量：

• koa-body
• koa-better-body
• koa-body-parser
• koa-bodyparser

• koa-body
• koa-更好的身体
• koa-body-parser
• koa-bodyparser

And I wanted to find the most minimalist/close to express/koa/nodeway/philosophy of doing things.

我想找到最简约/最接近express/koa/node的做事方式/哲学。

So here it is. Below. In accepted answer. Hope this helps.

所以在这里。以下。在接受的答案中。希望这可以帮助。

采纳答案by eightyfive

You have to use koa-multeras stated in the official Koa wiki.

您必须按照官方Koa wiki中的说明使用koa-multer。

So a simple setup would look like:

所以一个简单的设置看起来像：

const koa = require('koa');
const multer = require('koa-multer');

const app = koa();

app.use(multer());

app.use(function *() {
  this.body = this.req.body;
});

A couple of notes:

一些注意事项：

• Multer will only parse bodies of requests of type multipart/form-data
• Noticethe use of this.req.bodyinstead of Koa's supercharged this.request(not sure if this is intentional but this is confusing for sure... I would expect the parsed bodyto be available on this.request...)

• Multer 只会解析类型请求的主体 multipart/form-data
• 请注意使用this.req.body而不是 Koa 的增压this.request（不确定这是否是故意的，但这肯定令人困惑......我希望解析的内容body可以在this.request......上使用）

And sending this HTML form as FormData:

并将此 HTML 表单发送为FormData：

<form>
  <input type="hidden" name="topsecret" value="1">
  <input type="text" name="area51[lat]" value="37.235065">
  <input type="text" name="area51[lng]" value="-115.811117">
  ...
</form>

Would give you access to nested properties as expected:

会让您按预期访问嵌套属性：

// -> console.log(this.req.body)
{
  "topsecret": 1,
  "area51": {
    "lat": "37.235065",
    "lng": "-115.811117",
  }
}

回答by silkAdmin

For Koa2, you can use async-busboyas other solutions dont support promisesor async/await.

对于Koa2，您可以使用async- busboy，因为其他解决方案不支持promises或async/await。

Example from the docs:

文档中的示例：

import asyncBusboy from 'async-busboy';

// Koa 2 middleware
async function(ctx, next) {
  const {files, fields} = await asyncBusboy(ctx.req);

  // Make some validation on the fields before upload to S3
  if ( checkFiles(fields) ) {
    files.map(uploadFilesToS3)
  } else {
    return 'error';
  }
}

回答by satanas

I went through the same investigation than you and here are other ways to achieve multipart/form-databody parsing with Koa.

我和你经历了同样的调查，这里有其他方法可以multipart/form-data用 Koa实现身体解析。

co-busboy:

搭档:

var koa = require('koa');
var parse = require('co-busboy');

const app = koa();

app.use(function* (next) {
  // the body isn't multipart, so busboy can't parse it 
  if (!this.request.is('multipart/*')) return yield next;

  var parts = parse(this),
      part,
      fields = {};
  while (part = yield parts) {
    if (part.length) {
      // arrays are busboy fields 
      console.log('key: ' + part[0]);
      console.log('value: ' + part[1]);

      fields[part[0]] = part[1];
    } else {
      // it's a stream, you can do something like:
      // part.pipe(fs.createWriteStream('some file.txt'));
    }
  }

  this.body = JSON.stringify(fields, null, 2);
})

koa-body:

koa-body:

var koa = require('koa');
var router = require('koa-router');
var koaBody = require('koa-body')({ multipart: true });

const app = koa();

app.use(router(app));

app.post('/', koaBody, function *(next) {
  console.log(this.request.body.fields);

  this.body = JSON.stringify(this.request.body, null, 2);
});

In both cases you will have a response like:

在这两种情况下，您都会得到如下响应：

{
  "topsecret": 1,
  "area51": {
    "lat": "37.235065",
    "lng": "-115.811117",
  }
}

But personally, I prefer the way koa-body works. Plus, is compatible with other middleware like koa-validate.

但就个人而言，我更喜欢 koa-body 的工作方式。另外，与其他中间件兼容，如koa-validate。

Also, if you specify an upload dir to koa-body, it will save the uploaded file for you:

另外，如果你指定一个上传目录到 koa-body，它会为你保存上传的文件：

var koaBody = require('koa-body')({
  multipart: true,
  formidable: { uploadDir: path.join(__dirname, 'tmp') }
});

回答by ns16

I have three solutions that works for me:

我有三个适合我的解决方案：

1. koa-body, note it parses multipart/form-dataonly with multipart: trueoption.

1. koa-body，请注意它multipart/form-data仅解析multipart: true选项。

const Koa = require('koa');
const koaBody = require('koa-body');
const Router = require('koa-router');

const app = new Koa();
const router = new Router();

app.use(koaBody({ multipart: true }));

router.post('/', async ctx => {
    const body = ctx.request.body;
    // some code...
});

app.use(router.routes());

app.listen(3000);

1. koa-bodyparser, parses multipart/form-dataonly with koa2-formidablemiddleware before it.

2. koa-bodyparser，multipart/form-data只解析koa2-formidable它之前的中间件。

const Koa = require('koa');
const bodyParser = require('koa-bodyparser');
const formidable = require('koa2-formidable');
const Router = require('koa-router');

const app = new Koa();
const router = new Router();

app.use(formidable());
app.use(bodyParser());

router.post('/', async ctx => {
    const body = ctx.request.body;
    // some code...
});

app.use(router.routes());

app.listen(3000);

1. @koa/multer, note it parses multipart/form-dataonly if installed multerpackage. Also note that koa-multeris deprecated, do not use it.

3. @koa/multer，请注意它multipart/form-data仅在安装multer包时解析。另请注意，koa-multer已弃用，请勿使用它。

const Koa = require('koa');
const Router = require('koa-router');
const multer = require('@koa/multer');

const app = new Koa();
const router = new Router();
const upload = multer(); // you can pass options here

app.use(upload.any());

router.post('/', async ctx => {
    const body = ctx.request.body;
    // some code...
});

app.use(router.routes());

app.listen(3000);