req.field('key', 'value') is broken

[magicdawn]

the 2.0.0 release use form-data@1.0.0-rc4
while will cause

TypeError: Cannot read property 'path' of null
    at FormData._getContentDisposition (/.../node_modules/superagent/node_modules/form-data/lib/form_data.js:195:43)
    at FormData._multiPartHeader (/.../node_modules/superagent/node_modules/form-data/lib/form_data.js:169:33)
    at FormData.append (/.../node_modules/superagent/node_modules/form-data/lib/form_data.js:64:21)
    at Request.exports.field (/.../node_modules/superagent/lib/request-base.js:184:23)

the call chain

• https://github.com/visionmedia/superagent/blob/v2.2.0/lib/request-base.js#L184
• https://github.com/form-data/form-data/blob/v1.0.0-rc4/lib/form_data.js#L64
• https://github.com/form-data/form-data/blob/v1.0.0-rc4/lib/form_data.js#L169
• https://github.com/form-data/form-data/blob/v1.0.0-rc4/lib/form_data.js#L195

[magicdawn]

value.length <- the exception

[kornelski]

That looks like a bug in FormData (I don't see what we can do about it in superagent). Can you report the problem there?

[magicdawn]

I'm sorry, Just found that error happens when the value is empty.
And can be reproduced by code below:

.field('key'), value is undefined

'use strict';

const request = require('superagent');
const co = require('co');

const main = co.wrap(function*() {
  const res = yield request
    .post('http://localhost')
    .field('x');
});

if (module === process.mainModule) {
  main().catch(e => console.error(e.stack || e));
}

So should we add a assert(value, 'value can not be empty') here or the form-data repo ?

[magicdawn]

what does an empty field means in a multipart/form-data ?
Looks there already got some clues

• null check inside append() form-data/form-data#147
• Update to form-data RC4 and pass null values to it request/request#2208

[kornelski]

.set('header',undefined) throws, .query('field',undefined) sets query string to ?field, so it could go either way.

Throwing may be easier, but making undefined remove fields from the form could be more useful.

[magicdawn]

Since form-data is going to fix this in v2, and current this will throw a unknown error
TypeError: Cannot read property 'path' of null, and I found a hidden bug in my bussiness code after figuring out what really happens. 😂

[magicdawn]

I guess it's better to close solved issues to let the opening issues number down. 😂