koa-lite/lib/application.js

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'use strict';
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/**
* Module dependencies.
*/
const debug = require('debug')('koa:application');
const Emitter = require('events').EventEmitter;
const compose_es7 = require('composition');
const onFinished = require('on-finished');
const response = require('./response');
const compose = require('koa-compose');
const isJSON = require('koa-is-json');
const context = require('./context');
const request = require('./request');
const statuses = require('statuses');
const Cookies = require('cookies');
const accepts = require('accepts');
const assert = require('assert');
const Stream = require('stream');
const http = require('http');
const only = require('only');
const co = require('co');
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/**
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* Expose `Application` class.
* Inherits from `Emitter.prototype`.
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*/
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module.exports = class Application extends Emitter {
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/**
* Initialize a new `Application`.
*
* @api public
*/
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constructor() {
super();
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this.env = process.env.NODE_ENV || 'development';
this.subdomainOffset = 2;
this.middleware = [];
this.context = Object.create(context);
this.request = Object.create(request);
this.response = Object.create(response);
}
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/**
* Shorthand for:
*
* http.createServer(app.callback()).listen(...)
*
* @param {Mixed} ...
* @return {Server}
* @api public
*/
listen() {
debug('listen');
const server = http.createServer(this.callback());
return server.listen.apply(server, arguments);
}
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/**
* Return JSON representation.
* We only bother showing settings.
*
* @return {Object}
* @api public
*/
toJSON() {
return only(this, [
'subdomainOffset',
'env'
]);
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}
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inspect() {
return this.toJSON();
}
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/**
* Use the given middleware `fn`.
*
* @param {GeneratorFunction} fn
* @return {Application} self
* @api public
*/
use(fn) {
if (!this.experimental) {
// es7 async functions are allowed
assert(fn && 'GeneratorFunction' == fn.constructor.name, 'app.use() requires a generator function');
}
debug('use %s', fn._name || fn.name || '-');
this.middleware.push(fn);
return this;
}
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/**
* Return a request handler callback
* for node's native http server.
*
* @return {Function}
* @api public
*/
callback() {
const fn = this.experimental
? compose_es7(this.middleware)
: co.wrap(compose(this.middleware));
if (!this.listeners('error').length) this.on('error', this.onerror);
return (req, res) => {
res.statusCode = 404;
const ctx = this.createContext(req, res);
onFinished(res, ctx.onerror);
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fn.call(ctx).then(function() {
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respond.call(ctx);
}).catch(ctx.onerror);
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};
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}
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/**
* Initialize a new context.
*
* @api private
*/
createContext(req, res) {
const context = Object.create(this.context);
const request = context.request = Object.create(this.request);
const response = context.response = Object.create(this.response);
context.app = request.app = response.app = this;
context.req = request.req = response.req = req;
context.res = request.res = response.res = res;
request.ctx = response.ctx = context;
request.response = response;
response.request = request;
context.onerror = context.onerror.bind(context);
context.originalUrl = request.originalUrl = req.url;
context.cookies = new Cookies(req, res, this.keys);
context.accept = request.accept = accepts(req);
context.state = {};
return context;
}
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/**
* Default error handler.
*
* @param {Error} err
* @api private
*/
onerror(err) {
assert(err instanceof Error, `non-error thrown: ${err}`);
if (404 == err.status || err.expose) return;
if (this.silent) return;
// DEPRECATE env-specific logging in v2
if ('test' == this.env) return;
const msg = err.stack || err.toString();
console.error();
console.error(msg.replace(/^/gm, ' '));
console.error();
}
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};
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/**
* Response helper.
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*/
function respond() {
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// allow bypassing koa
if (false === this.respond) return;
const res = this.res;
if (res.headersSent || !this.writable) return;
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var body = this.body;
const code = this.status;
// ignore body
if (statuses.empty[code]) {
// strip headers
this.body = null;
return res.end();
}
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if ('HEAD' == this.method) {
if (isJSON(body)) this.length = Buffer.byteLength(JSON.stringify(body));
return res.end();
}
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// status body
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if (null == body) {
this.type = 'text';
body = this.message || String(code);
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this.length = Buffer.byteLength(body);
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return res.end(body);
}
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// responses
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if (Buffer.isBuffer(body)) return res.end(body);
if ('string' == typeof body) return res.end(body);
if (body instanceof Stream) return body.pipe(res);
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// body: json
body = JSON.stringify(body);
this.length = Buffer.byteLength(body);
res.end(body);
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}