Access the raw body of a request in koa.js

Question

I have created an API using io.js and koa.js.

As a body parser middleware I am using koa-body, which in turn uses co-body.

On one of my API endpoints I am receiving POST requests, and I need access to the raw body of the request, because I need to encode it to verify if the request is valid.

Is there any way to access the raw body of the request? I tried to use the raw-body middleware, but if I use it before I call koa-body, the co-body used in koa-body breaks. If I use it after koa-body it does not work.

   app.use(function*(next){
    let rawRequestBody = yield rawBody(this.req);
    this.rawRequestBody = rawRequestBody;

    yield next;
  });

---

EDIT:

I think that I found a workaround, but I don't know if this is the best solution. I think that @greim answer may be a better solution to this problem.

I added the following code before I use koa-body:

app.use(function *(next) {

    let url = this.req.url;

    if(this.req.method == 'POST') {
      let that = this;
      this.req.rawBody = '';

      this.req.on('data', function(chunk) {
        that.req.rawBody += chunk;
      });
    }

    yield next;
  });

Iny

Answer 1

It only makes sense to capture the stream once.

You can capture the request body as a string or buffer (I assume this is what you mean by "raw" body) using the raw-body utility, and then keep a reference to it as shown in your own code, such that:

let rawRequestBody = yield rawBody(this.req);
this.rawRequestBody = rawRequestBody;
console.log(typeof this.rawRequestBody); // "string"

Once you do that, don't also use koa-body or co-body, since those are also stream-capturing utilities which assume you haven't yet captured the stream. To make the request body accessible as JSON (for example) simply do this:

this.jsonRequestBody = JSON.parse(this.rawRequestBody);
console.log(typeof this.jsonRequestBody); // "object"

Beers

Answer 2

Why we can't use multiple body parser(co-body, koa-body) is because by defination it must prepare ctx.request.body for next middleware to use, this means when a body parser middleware "await next()" to transfer control to next middleware the ctx.req is consumed(or end).

Any body parser middleware for coordination with other request body consumer(one that listen "data" or "end" event on ctx.req), must makesure it "synchronize" listen events(like "data" or "end") on ctx.req. This is not true for co-body and koa-body(use co-body) which do it in "Promise.resolve().then", if "data" or "end" events triggered before one listen these event, data missing(lose "data" event) or error(listen on ended stream) will happen.

@greim is right, but most of the time, we use a high level middleware(such as joi-router) which has force to use a body parser middleware and we have no control, this is still a problem.

Lardy

Answer 3

It would be nice to have a quickstart code example in the docs for this, but it seems like there's none. Here's a working example that I have:

const multipartBodyParser = require('koa-body');
const unparsed = require('koa-body/unparsed.js');

const app = new Koa();

app.use(multipartBodyParser({
  includeUnparsed: true,
  multipart: true,
}));

app.listen(3100);



// Now access the raw request body like this :
ctx.request.body[unparsed];

Tibbitts

> includeUnparsed {Boolean} Toggles co-body returnRawBody option; if set to true, for form encodedand and JSON requests the raw, unparsed requesty body will be attached to ctx.request.body using a Symbol, default false. This koa-body option is only for "application/x-www-form-urlencoded" and "application/json" content-type. For other types such as "application/octet-stream", there will be no unparsed body in the ctx.request.body. – Amaranth

Answer 4

I had a similar problem using koa-bodyparser and the problem was that the external webhook didn't sent the application/json content header, so it did not parsed the body. I could solve the problem by explicitly telling the parser to parse json on this route.

 .use(bodyParser({
      detectJSON: function (ctx) {
        return /webhook\/json-route/i.test(ctx.path);
      },
    }))

Evy

Answer 5

You can access raw request body by ctx.request.rawBody

ref: enter link description here

Montherlant