Koa Querystring

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By default, Koa uses the native querystring module which does not provide nesting support.
This patches a koa app with nesting support via the qs support,
which is also used by Connect and Express.

Simply wrap a koa app with this module:

``js
// Koa 1.x.x
const koa = require('koa')
const app = koa()
require('koa-qs')(app)
// Koa 2.x.x
const Koa = require('koa')
const app = new Koa()
require('koa-qs')(app)
`

Optional parse mode

There're three parse mode.

extended mode

The default mode, use [qs] module.

`js
require('koa-qs')(app, 'extended')
`

simple mode

Use querystring module, same as koa does by default.
If you want to use this mode, don't use this module.

strict mode

This mode make this.query.foo return strict array.

`js
require('koa-qs')(app, 'strict')
`

#### What's different

A normal request GET /foo?p=a&q=foo&q=bar.

- before patch

`js
console.log('%j', this.query);
{
"p": "a",
"q": ["foo", "bar"]
}
`

- after patch

`js
console.log('%j', this.query);
{
"p": ["a"],
"q": ["foo", "bar"]
}
`

first mode

This mode make this.query.foo return strict string. Disable multi values.

If querystring contains multi same name params, return the first item.

`js
require('koa-qs')(app, 'first')
`

In 95% use cases, application only want string query params.

This patch can avoid some stupid TypeError and some security issues like MongoDB inject
when the developers forget handling query params type check.

#### What's different

A normal request GET /foo?p=a,b&p=b,c.

- before patch

`js
console.log('%j', this.query.p);
["a,b", "b,c"]
`

- after patch

`js
console.log('%j', this.query.p);
"a,b"
``

License

MIT