Koa: Response headers will be ignored/removed while using ctx.throw.

[LvChengbin]

ctx.set( 'Access-Control-Allow-Origin', '*' );
ctx.throw( 404 );

By using the code above, the header of Access-Control-Allow-Origin will not be sent with responding. Even though I can use res.statusCode instead, but I think the ctx.throw method should not remove response headers.

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[jonathanong]

yes, that is by design. this should be handled by an error handler:

app.use(async (ctx, next) => {
  try {
    await next()
  } catch (err) {
    ctx.set('Access-Control-Allow-Origin', '*')
    ctx.status = err.status
})

app.use(async (ctx) => {
  ctx.throw(404)
})

[mutoe]

According to my usage, you also put it in the try block like this

app.use(async (ctx, next) => {
  try {
    ctx.set('Access-Control-Allow-Origin', '*')
    await next()
  } catch (err) {
    ctx.set('Access-Control-Allow-Origin', '*')
    ctx.status = err.status
})

Otherwise, there will be no header you set in the normal code.

[snuggs]

@mutoe @jonathanong @LvChengbin FWIW we use the second parameter in context.throw. YMMV

[Yorkshireman]

I had the same problem and solved it with this error handler middleware:

export default async (ctx, next) => {
  return next().catch(err => {
    const { statusCode, message } = err;

    ctx.type = 'json';
    ctx.status = statusCode || 500;
    ctx.body = {
      status: 'error',
      message
    };

    ctx.app.emit('error', err, ctx);
  });
};

more info here: https://stackoverflow.com/questions/52623644/how-to-make-koa-ctx-throw-use-application-json-rather-than-text-plain

[lichangwei]

any updates? I am also confused about this problem.

[niftylettuce]

Feel free to use https://github.com/ladjs/koa-better-error-handler.