The context object (`ctx`) contains all the requests related information. They are accessible through `ctx.request`, from [controllers](controllers.md) and [policies](policies.md).
Get request `Content-Type` void of parameters such as "charset".
```js
const ct = ctx.request.type;
// => "image/png"
```
### request.charset
Get request charset when present, or `undefined`:
```js
ctx.request.charset;
// => "utf-8"
```
### request.query
Get parsed query-string, returning an empty object when no
query-string is present. Note that this getter does _not_
support nested parsing.
For example "color=blue&size=small":
```js
{
color: 'blue',
size: 'small'
}
```
### request.query=
Set query-string to the given object. Note that this
setter does _not_ support nested objects.
```js
ctx.query = { next: '/login' };
```
### request.fresh
Check if a request cache is "fresh", aka the contents have not changed. This
method is for cache negotiation between `If-None-Match` / `ETag`, and `If-Modified-Since` and `Last-Modified`. It should be referenced after setting one or more of these response headers.
```js
// freshness check requires status 20x or 304
ctx.status = 200;
ctx.set('ETag', '123');
// cache is ok
if (ctx.fresh) {
ctx.status = 304;
return;
}
// cache is stale
// fetch new data
ctx.body = await db.find('something');
```
### request.stale
Inverse of `request.fresh`.
### request.protocol
Return request protocol, "https" or "http". Supports `X-Forwarded-Proto`
when `app.proxy` is __true__.
### request.secure
Shorthand for `ctx.protocol == "https"` to check if a request was
issued via TLS.
### request.ip
Request remote address. Supports `X-Forwarded-For` when `app.proxy`
is __true__.
### request.ips
When `X-Forwarded-For` is present and `app.proxy` is enabled an array
of these ips is returned, ordered from upstream -> downstream. When disabled
an empty array is returned.
### request.subdomains
Return subdomains as an array.
Subdomains are the dot-separated parts of the host before the main domain of
the app. By default, the domain of the app is assumed to be the last two
parts of the host. This can be changed by setting `app.subdomainOffset`.
For example, if the domain is "tobi.ferrets.example.com":
If `app.subdomainOffset` is not set, `ctx.subdomains` is `["ferrets", "tobi"]`.
If `app.subdomainOffset` is 3, `ctx.subdomains` is `["tobi"]`.
### request.is(types...)
Check if the incoming request contains the "Content-Type"
Koa's `request` object includes helpful content negotiation utilities powered by [accepts](http://github.com/expressjs/accepts) and [negotiator](https://github.com/federomero/negotiator). These utilities are:
-`request.accepts(types)`
-`request.acceptsEncodings(types)`
-`request.acceptsCharsets(charsets)`
-`request.acceptsLanguages(langs)`
If no types are supplied, __all__ acceptable types are returned.
If multiple types are supplied, the best match will be returned. If no matches are found, a `false` is returned, and you should send a `406 "Not Acceptable"` response to the client.
In the case of missing accept headers where any type is acceptable, the first type will be returned. Thus, the order of types you supply is important.
### request.accepts(types)
Check if the given `type(s)` is acceptable, returning the best match when true, otherwise `false`. The `type` value may be one or more mime type string
such as "application/json", the extension name
such as "json", or an array `["json", "html", "text/plain"]`.
```js
// Accept: text/html
ctx.accepts('html');
// => "html"
// Accept: text/*, application/json
ctx.accepts('html');
// => "html"
ctx.accepts('text/html');
// => "text/html"
ctx.accepts('json', 'text');
// => "json"
ctx.accepts('application/json');
// => "application/json"
// Accept: text/*, application/json
ctx.accepts('image/png');
ctx.accepts('png');
// => false
// Accept: text/*;q=.5, application/json
ctx.accepts(['html', 'json']);
ctx.accepts('html', 'json');
// => "json"
// No Accept header
ctx.accepts('html', 'json');
// => "html"
ctx.accepts('json', 'html');
// => "json"
```
You may call `ctx.accepts()` as many times as you like,
or use a switch:
```js
switch (ctx.accepts('json', 'html', 'text')) {
case 'json': break;
case 'html': break;
case 'text': break;
default: ctx.throw(406, 'json, html, or text only');
}
```
### request.acceptsEncodings(encodings)
Check if `encodings` are acceptable, returning the best match when true, otherwise `false`. Note that you should include `identity` as one of the encodings!
When no arguments are given all accepted encodings
are returned as an array:
```js
// Accept-Encoding: gzip, deflate
ctx.acceptsEncodings();
// => ["gzip", "deflate", "identity"]
```
Note that the `identity` encoding (which means no encoding) could be unacceptable if the client explicitly sends `identity;q=0`. Although this is an edge case, you should still handle the case where this method returns `false`.
