[英]How to call a function outside of an emitted event call function
如果這不清楚,我很抱歉,已經晚了,我不知道如何最好地解釋它。
我正在使用事件發射器將數據從服務器響應傳遞到另一個文件中單獨類中的函數,但是當嘗試使用這些類中的方法時, this
關鍵字顯然不起作用(因為在這種情況下, this
是指服務器事件發射器) - 我將如何在類本身中引用函數? 我提供了代碼來幫助更好地說明我的觀點
服務類.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)
}
}
服務器.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,我試圖調用 StreamService 類的 get 方法 - 但因為它是通過server.js
的發射器直接調用的, this
特指Server.js
類 - 有什么方法可以使用StreamService.get()
? 我顯然可以重寫方法本身內部的代碼,但是當它就在那里時似乎沒有必要?
改變這個:
twitchListener.on('live', this.sendLiveAlert)
對此:
twitchListener.on('live', this.sendLiveAlert.bind(this))
或者,您也可以這樣做:
twitchListener.on('live', (...args) => {
this.sendLiveAlert(...args);
});
使用.bind()
它創建一個函數包裝器,為您重置this
的正確值。 在箭頭函數的情況下,它為您保留了this
的詞法值。
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