Question

1. I need to write a function which when given the path of a folder
   scans the files rooted at that folder.
2. And then I need to display the directory structure at that folder.

I know how to do 2 (I am going to use jstree to display it in the browser).

Answer 1

EDIT FOR 1.16: Enough people still hit this answer, that I thought I’d update it for Go 1.16.

The function filepath.WalkDir introduced in Go 1.16 has better performance than filepath.Walk mentioned in the previous edit. Here’s a working example:

package main

import (
    "flag"
    "fmt"
    "io/fs"
    "path/filepath"
)

func visit(path string, di fs.DirEntry, err error) error {
    fmt.Printf("Visited: %s\n", path)
    return nil
}

func main() {
    flag.Parse()
    root := flag.Arg(0)
    err := filepath.WalkDir(root, visit)
    fmt.Printf("filepath.WalkDir() returned %v\n", err)
}

EDIT: Enough people still hit this answer, that I thought I’d update it for the Go1 API. This is a working example of filepath.Walk(). The original is below.

package main

import (
  "path/filepath"
  "os"
  "flag"
  "fmt"
)

func visit(path string, f os.FileInfo, err error) error {
  fmt.Printf("Visited: %s\n", path)
  return nil
} 


func main() {
  flag.Parse()
  root := flag.Arg(0)
  err := filepath.Walk(root, visit)
  fmt.Printf("filepath.Walk() returned %v\n", err)
}

Please note that filepath.Walk walks the directory tree recursively.

This is an example run:

$ mkdir -p dir1/dir2
$ touch dir1/file1 dir1/dir2/file2
$ go run walk.go dir1
Visited: dir1
Visited: dir1/dir2
Visited: dir1/dir2/file2
Visited: dir1/file1
filepath.Walk() returned <nil>

ORIGINAL ANSWER FOLLOWS: The interface for walking file paths has changed as of weekly.2011-09-16, see http://groups.google.com/group/golang-nuts/msg/e304dd9cf196a218. The code below will not work for release versions of GO in the near future.

There’s actually a function in the standard lib just for this: filepath.Walk.

package main

import (
    "path/filepath"
    "os"
    "flag"
)

type visitor int

// THIS CODE NO LONGER WORKS, PLEASE SEE ABOVE
func (v visitor) VisitDir(path string, f *os.FileInfo) bool {
    println(path)
    return true
} 

func (v visitor) VisitFile(path string, f *os.FileInfo) {
    println(path)
}

func main() {
    root := flag.Arg(0)
    filepath.Walk(root, visitor(0), nil)
}