Converting a JSON dir tree into indented plain text in GoLang

Question

I have a dir tree in a JSON struct that I'm trying to format in plain text. Formatting it in XML or YAML is pretty easy. Formatting it in plain text is much harder than I thought.

The JSON struct is formatted like this :

type File struct {
   Name     string  `json:"Name"`
   Children []*File `json:"Children"`
}

Since the JSON structure allows for 'children', the JSON is nested, and since it's a dir tree, I don't know how deep the nesting will get (within reason).

I need the converted JSON to look like this :

base_dir
  sub_dir_1
  sub_dir_2
    file_in_sub_dir_2
  sub_dir_3
  ...

Can anyone tell me how this could be done in a reasonably simple way? Right now I'm having to brute force with lots of looping and indenting with tabs, and I'm just sure there's a more elegant way in Go.

Thanks for the edit voutasaurus.

Dave Strickler
– Dave Strickler

2015-12-23 16:07:09 +00:00
Commented Dec 23, 2015 at 16:07 — Dave Strickler
– Dave Strickler, Commented Dec 23, 2015 at 16:07

score 3 · Accepted Answer · 2015-12-21 04:12:23Z

3

Write a function to recurse down the directory tree printing a file and its children. Increase the indent level when recursing down the tree.

func printFile(f *File, indent string) {
   fmt.Printf("%s%s\n", indent, f.Name)
   for _, f := range f.Children {
     printFile(f, indent+"  ")
   }
}

Call the function with the root of the tree:

printFile(root, "")

run the code on the playground

edited Dec 21, 2015 at 4:12

answered Dec 21, 2015 at 4:04

user5728991

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1 Comment

Dave Strickler Over a year ago

This works perfectly - many thanks. I didn't consider a recursive call into the printing function itself, which of course now is an obvious solution.

Salvador Dali · Accepted Answer · 2015-12-21 04:05:36Z

2

You can achieve this with MarshalIndent. Here is a go playground example.

instance := MyStruct{12344, "ohoasdoh", []int{1, 2, 3, 4, 5}}
res, _ := json.MarshalIndent(instance, "", "  ")
fmt.Println(string(res))

Which will give you something like:

{
  "Num": 12344,
  "Str": "ohoasdoh",
  "Arr": [
    1,
    2,
    3,
    4,
    5
  ]
}

answered Dec 21, 2015 at 4:05

Salvador Dali

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2 Comments

Dave Strickler Over a year ago

Thanks, but json.MarshalIndent outputs JSON (as it should). I was looking for a plain text output that's more human readable.

adam_0 Over a year ago

Though this doesn't answer the question, I upvoted it because it was the first result on Google where I was looking for exactly this.

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