[英]How to call a function outside of an emitted event call function
如果这不清楚,我很抱歉,已经晚了,我不知道如何最好地解释它。
我正在使用事件发射器将数据从服务器响应传递到另一个文件中单独类中的函数,但是当尝试使用这些类中的方法时, this
关键字显然不起作用(因为在这种情况下, this
是指服务器事件发射器) - 我将如何在类本身中引用函数? 我提供了代码来帮助更好地说明我的观点
服务类.js
class StreamService {
/**
*
* @param {} database
* @param {Collection<Guild>} guilds
*/
constructor (database, guilds,) {
.....
twitchListener.on('live', this.sendLiveAlert) // fire test method when we get a notification
// if there are streamers to monitor, being monitoring
winston.info('Stream service initialized')
}
..............
async get (url, params = null, headers = this.defaultHeaders) {
// check oauth token
const expirationDate = this.token.expires_in || 0
if (expirationDate <= Date.now() || !this.token) await this.getAccessToken()
// build URL
const index = 0
let paramsString = ''
for (const [key, value] of params.entries()) {
if (index === 0) {
paramsString += `?${key}=${value}`
} else {
paramsString += `&${key}=${value}`
}
}
const res = await fetch(url + paramsString, { method: 'GET', headers: headers })
if (!res.ok) {
winston.error(`Error performing GET request to ${url}`)
return null
}
return await res.json()
}
async sendLiveAlert(streamTitle, streamURL, avatar, userName, gameId, viewerCount, thumbnail, startDateTime) {
// get game name first (no headers needed)
const params = new Map()
params.set('id', gameId)
const gameData = await this.get('https://api.twitch.tv/heliix/games', params, this.defaultHeaders)
if(gameData) {
// get webhook and send message to channel
const webhookClient = new WebhookClient('755641606555697305', 'OWZvI01kUUf4AAIR9uv2z4CxRse3Ik8b0LKOluaOYKmhE33h0ypMLT0JJm3laomlZ05o')
const embed = new MessageEmbed()
.setTitle(`${userName} just went live on Twitch!`)
.setURL(streamURL)
.setThumbnail(avatar)
.addFields(
{ name: 'Now Playing', value: gameData.data[0].name },
{ name: 'Stream Title', value: streamTitle }
)
.setImage(thumbnail)
}
webhookClient.send('Webhook test', embed)
}
}
服务器.js
class TwitchWebhookListener extends EventEmitter {
......................
// Routes
server
.post((req, res) => {
console.log('Incoming POST request on /webhooks')
............................
const data = req.body.data[0]
if(!this.streamerLiveStatus.get(data.user_id) && data.type === 'live') {
// pass request body to bot for processing
this.emit(
'live',
data.title, // stream title
`https://twitch.tv/${data.user_name}`, // channel link
`https://avatar.glue-bot.xyz/twitch/${data.user_name}`, // streamer avatar
data.user_name,
data.game_id,
data.viewer_count,
data.thumbnail_url,
data.started_at // do we need this?
)
}
break
default:
res.send(`Unknown webhook for ${req.params.id}`)
break
}
} else {
console.log('The Signature did not match')
res.send('Ok')
}
} else {
console.log('It didn\'t seem to be a Twitch Hook')
res.send('Ok')
}
})
}
}
const listener = new TwitchWebhookListener()
listener.listen()
module.exports = listener
在sendLiveAlert
方法中,我试图调用 StreamService 类的 get 方法 - 但因为它是通过server.js
的发射器直接调用的, this
特指Server.js
类 - 有什么方法可以使用StreamService.get()
? 我显然可以重写方法本身内部的代码,但是当它就在那里时似乎没有必要?
改变这个:
twitchListener.on('live', this.sendLiveAlert)
对此:
twitchListener.on('live', this.sendLiveAlert.bind(this))
或者,您也可以这样做:
twitchListener.on('live', (...args) => {
this.sendLiveAlert(...args);
});
使用.bind()
它创建一个函数包装器,为您重置this
的正确值。 在箭头函数的情况下,它为您保留了this
的词法值。
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