golang无法写入文本文件：句柄无效

Question

Hello again everybody,

I apologize for asking another question so soon, but it just seems to be one thing after another with Go lately.

I have a working web page scraper (thanks to everybody's help) that grabs all the info I want from this wiki page: http://monsterhunter.wikia.com/wiki/MH4U:_Item_List

It then displays everything I want, no hiccups. However, when I go to write to a .txt file I get an error stating: "0 write mh4u.txt: The handle is invalid"

Here is my current code for reference:

package main

import (
    "fmt"
    "log"

    "github.com/PuerkitoBio/goquery"
    "os"
    "io"
)

func main() {

    filename := "mh4u.txt"
    file, err := os.Create(filename)

    if err!= nil {
        fmt.Println(err)
    }
    doc, err := goquery.NewDocument("http://www.ign.com/wikis/monster-hunter-4/Items")
    if err != nil {
        log.Fatal(err)
    }

    doc.Find("tbody").Each(func(i int, s *goquery.Selection) {

        s.Find("td").Each(func(j int, s2 *goquery.Selection) {

            if s3 := s2.Find("img"); s3 != nil && s3.Length() > 0 {
                return
            }

            fmt.Printf(s2.Text())
            n, err := io.WriteString(file, s2.Text())

            if err != nil {
                fmt.Println(n, err) 
            }
        })

        file.Close()
    })
}

Testing this code with other web sites leads me to believe that there is maybe some hidden characters that is giving the writer some issues, but that's the only thing I can guess.

Thanks so much for any suggestions/tips/solutions you can offer!

Answer 1

You're calling file.Close() inside a closure. If doc.Find("tbody").Each is called more than one time, you'll end up trying to write to a closed file. You should defer the file closing right after you've created it:

file, err := os.Create(filename)
if err != nil {
    log.Fatal(err)
}
defer file.Close()