Comments (3)
@joshua7v 哈囉,你需要先確定 Error 能拿到那個 request 的 url,之後程式碼大概會像下面這樣
const urls = [...]; // 你的 urls
function crawler(...urls) {
return Observable.from(urls)
.mergeMap(url => <promise of requests>, <concurrency>)
.map(res => <data object needed>)
.concatAll()
.withLatestFrom(<db>, (x, y) => <query promise>)
.concatAll()
}
crawler(...urls)
.catch(e => {
// 先判斷是不是 request 發生錯誤
if(...) {
// 從 error 拿到發生錯誤的 request url
return crawler(e.url).retry(3) // 可以設定 retry 幾次
}
// 如果不是要做什麼,寫在這
})
.subscribe(...)
from learn-rxjs-in-30-days.
@Jerry-Hong 謝謝
crawler(...urls)
.catch(e => {
// 先判斷是不是 request 發生錯誤
if(...) {
// 從 error 拿到發生錯誤的 request url
return crawler(e.url).retry(3) // 可以設定 retry 幾次
}
// 如果不是要做什麼,寫在這
})
catch 到錯誤后返回用發生錯誤的 url 創建的 observable 之後
執行完就 complete 了
原來的 observable 中的 requests 就不會執行了
是我哪裡寫的不對嗎
from learn-rxjs-in-30-days.
@joshua7v Sorry 我寫錯了,應該這麼做
const urls = [...]; // 你的 urls
function crawler(...urls) {
return Observable.from(urls)
.mergeMap(url => Observable.from(fetch(url))
.retry(3)
.catch(error => {
// 這裡可以直接 log 或者傳到通訊頻道
// 如果不想 一個一個發可以先暫存在一個 array 裡,等到全部 complete 再發送
return Observable.empty();
}), <concurrency>)
.map(res => <data object needed>)
.concatAll()
.withLatestFrom(<db>, (x, y) => <query promise>)
.concatAll()
}
crawler(...urls)
.catch(e => {
// 這裡處理整體錯誤
})
.subscribe(...)
catch return 的 observable 會取代掉原先的,所以後面的才會消失。
from learn-rxjs-in-30-days.
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