F#:处理网络例外
问题描述:
我是编程新手,F#是我的第一语言。F#:处理网络例外
这里是我的代码的相关片段:
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
我一直在使用F#交互式测试功能fetchHtmlAsync和getFighterNameFromPage。他们都很好。
当我构建和运行解决方案,但是,我得到了以下错误消息:
An unhandled exception of type 'System.Net.WebException' occurred in FSharp.Core.dll Additional information: The remote server returned an error: (404) Not Found.
出了什么问题?我应该做什么改变?
答
将您的try
with
放入async
之内。
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")
}
笑... 6秒时:d – Carsten 2015-03-31 17:20:40
哈哈是啊,我只是评论同样的事情在你的答案 – albertjan 2015-03-31 17:21:36
谢谢,albertjan!事实证明,我是一个白痴......我最初是按照你的方式编写我的代码,但因为我忘记重建我的解决方案,所以我一直收到一条错误消息,这促使我开始做出不必要和不准确的更改。现在我刚刚重建,一切都很好。再次感谢你的帮助。 :-) – 2015-03-31 17:44:42