更改文件名路径目录

Question

I need to change filename paths relative to a given folder.
I am dealing with multi-user shared buckets and it would be nice for the user not to know the complete file path.

I have an example below but it seems a bit dirty.

package main

import (
    "fmt"
    "strings"
)

func main() {
    secretUrl := "allusers/user/home/path/to/file"
    separator := "home/"

    newUrl := strings.Split(secretUrl, separator)

    newUserUrl := separator + newUrl[len(newUrl)-1]
    fmt.Printf("%q
", newUserUrl)

}

Also, the new path needs to start from the separating point.

Is there another way to do this more elegantly? Examples would be appreciated.

Answer 1

I think a nice platform-independent solution is to use the golang path/filepath Split function. Does not make assumptions about what path separators look like, handles volumes, etc...

import (
    "path/filepath"
)

func subpath(homeDir, prevDir string) string {
    subFiles := ""
    for {
        dir, file := filepath.Split(prevDir)
        if len(subFiles) > 0 {
            subFiles = file + string(filepath.Separator) + subFiles
        } else {
            subFiles = file
        }
        if file == homeDir {
            break
        }
        if len(dir) == 0 || dir == prevDir {
            break
        }
        prevDir = dir[:len(dir) - 1]
    }
    return subFiles
}

Call with

subpath("home", "allusers/user/home/path/to/file")

To handle cases where "home" may appear more than once and you wish to match the first:

func subpath(homeDir, prevDir string) (subFiles string, found bool) {
    for {
        dir, file := filepath.Split(prevDir)
        if len(subFiles) > 0 {
            subFiles = file + string(filepath.Separator) + subFiles
        } else {
            subFiles = file
        }
        if len(dir) == 0 || dir == prevDir {
            return
        }
        prevDir = dir[:len(dir) - 1]
        if file == homeDir {
            found = true
            // look for it lower down
            lower, foundAgain := subpath(homeDir, prevDir)
            if foundAgain {
                subFiles = lower + string(filepath.Separator) + subFiles
            }
            return
        }
    }
}

Call with

path, found = subpath("home", "allusers/user/home/path/home2/home/to/file")
if found {
    fmt.Printf("%q
", path)
} else {
    fmt.Printf("not found
")
}