Koa example in Typescript - cant modify stream

[webrunner42]

Koa example in Typescript - cant modify stream

[webrunner42]

For people in the future3 who have this problem:

 let chunk;
    while (null !== (chunk = ctx.req.read())) {
      // get rid of the existing things
    }
    const toUnshift = JSON.stringify(bodyJson);
    ctx.req.unshift(toUnshift);
    ctx.req.headers["content-length"] = toUnshift.length.toString();

this will clobber the existing body and replace it with your own

[kevinddchen]

Your specific use-case may be handled by the setup() callback: https://boardgame.io/documentation/#/api/Game

However, I also want to add middleware to modify the server behavior, e.g. invalidate player names upon joining a match if another player has that same name. #1107 is another issue on the same topic.

[kevinddchen]

@webrunner42 Thank you very much for your snippet! 🎉 I was able to arrive at a good workaround. My use-case was pretty simple, since I just needed to intercept the body and then pass it without any changes. For reference, this is what I used:

async (ctx, next) => { 

    const chunks = [];
    let chunk;
    while (null !== (chunk = ctx.req.read())) {
      chunks.push(chunk);
    }

    const rawBody = Buffer.concat(chunks).toString('utf8');
    const body = JSON.parse(rawBody);

    // do stuff

    ctx.req.unshift(rawBody);
    ctx.req.headers["content-length"] = rawBody.length.toString();
    await next();
  });

It seems that a more permanent fix may be added to the koa library: koajs/bodyparser#127.