jsonpath

This package extends the json.Decoder to support navigating a stream of JSON tokens. You should be able to use this extended Decoder places where a json.Decoder would have been used.

This Decoder has the following enhancements...

The Scan method supports scanning a JSON stream while extracting particular values along the way using PathActions.
The SeekTo method supports seeking forward in a JSON token stream to a particular path.
The Path method returns the path of the most recently parsed token.
The Token method has been modified to distinguish between strings that are object keys and strings that are values. Object key strings are returned as the KeyString type rather than a native string.

Installation

go get -u github.com/exponent-io/jsonpath

Example Usage

SeekTo

import "github.com/exponent-io/jsonpath"

var j = []byte(`[
  {"Space": "YCbCr", "Point": {"Y": 255, "Cb": 0, "Cr": -10}},
  {"Space": "RGB",   "Point": {"R": 98, "G": 218, "B": 255}}
]`)

w := json.NewDecoder(bytes.NewReader(j))
var v interface{}

w.SeekTo(1, "Point", "G")
w.Decode(&v) // v is 218

Scan with PathActions

var j = []byte(`{"colors":[
  {"Space": "YCbCr", "Point": {"Y": 255, "Cb": 0, "Cr": -10, "A": 58}},
  {"Space": "RGB",   "Point": {"R": 98, "G": 218, "B": 255, "A": 231}}
]}`)

var actions PathActions

// Extract the value at Point.A
actions.Add(func(d *Decoder) error {
  var alpha int
  err := d.Decode(&alpha)
  fmt.Printf("Alpha: %v\n", alpha)
  return err
}, "Point", "A")

w := NewDecoder(bytes.NewReader(j))
w.SeekTo("colors", 0)

var ok = true
var err error
for ok {
  ok, err = w.Scan(&actions)
  if err != nil && err != io.EOF {
    panic(err)
  }
}