我是编程新手,F#是我的第一语言。
以下是我的代码的相关摘要:
let downloadHtmlToDiskAsync (fighterHtmlDirectory: string) (fighterBaseUrl: string) (fighterId: int) =
let fighterUrl = fighterBaseUrl + fighterId.ToString()
try
async {
let! html = fetchHtmlAsync fighterUrl
let fighterName = getFighterNameFromPage html
let newTextFile = File.Create(fighterHtmlDirectory + "\\" + fighterId.ToString("00000") + " " + fighterName.TrimEnd([|' '|]) + ".html")
use file = new StreamWriter(newTextFile)
file.Write(html)
file.Close()
}
with
:? System.Net.WebException -> async {File.AppendAllText("G:\User\WebScraping\Invalid Urls.txt", fighterUrl + "\n")}
let downloadFighterDatabase (directoryPath: string) (fighterBaseUrl: string) (beginningFighterId: int) (endFighterId: int) =
let allFighterIds = [for id in beginningFighterId .. endFighterId -> id]
allFighterIds
|> Seq.map (fun fighterId -> downloadHtmlToDiskAsync directoryPath fighterBaseUrl fighterId)
|> Async.Parallel
|> Async.RunSynchronously
我使用F#Interactive测试了函数fetchHtmlAsync和getFighterNameFromPage。他们都工作正常。
但是,当我构建并运行解决方案时,我收到以下错误消息:
未处理的类型' System.Net.WebException'发生在FSharp.Core.dll中 附加信息:远程服务器返回错误:(404)Not Found。
出了什么问题?我应该做些什么改变?
答案 0 :(得分:3)
将try
with
放入async
。
let downloadHtmlToDiskAsync (fighterHtmlDirectory: string) (fighterBaseUrl: string) (fighterId: int) =
let fighterUrl = fighterBaseUrl + fighterId.ToString()
async {
try
let! html = fetchHtmlAsync fighterUrl
let fighterName = getFighterNameFromPage html
let newTextFile = File.Create(fighterHtmlDirectory + "\\" + fighterId.ToString("00000") + " " + fighterName.TrimEnd([|' '|]) + ".html")
use file = new StreamWriter(newTextFile)
file.Write(html)
file.Close()
with
:? System.Net.WebException -> File.AppendAllText("G:\User\WebScraping\Invalid Urls.txt", fighterUrl + "\n")
}