jq's Introduction

jq

A high performance Golang implementation of the incredibly useful jq command line tool.

Rather than marshalling json elements into go instances, jq opts to manipulate the json elements as raw []byte. This is especially useful for apps that need to handle dynamic json data.

Using jq consists of creation an Op and then calling Apply on the Op to transform one []byte into the desired []byte. Ops may be chained together to form a transformation chain similar to how the command line jq works.

Installation

go get github.com/savaki/jq

Example

package main

import (
	"fmt"

	"github.com/savaki/jq"
)

func main() {
	op, _ := jq.Parse(".hello")           // create an Op
	data := []byte(`{"hello":"world"}`)   // sample input
	value, _ := op.Apply(data)            // value == '"world"'
	fmt.Println(string(value))
}

Syntax

The initial goal is to support all the selectors the original jq command line supports.

syntax	meaning
.	unchanged input
.foo	value at key
.foo.bar	value at nested key
.[0]	value at specified element of array
.[0:1]	array of specified elements of array, inclusive
.foo.[0]	nested value

Examples

Data

{
  "string": "a",
  "number": 1.23,
  "simple": ["a", "b", "c"],
  "mixed": [
    "a",
    1,
    {"hello":"world"}
  ],
  "object": {
    "first": "joe",
    "array": [1,2,3]
  }
}

syntax	value
.string	"a"
.number	1.23
.simple	["a", "b", "c"]
.simple.[0]	"a"
.simple.[0:1]	["a","b"]
.mixed.[1]	1
.object.first	"joe"
.object.array.[2]	3

Performance

BenchmarkAny-8         	20000000	        80.8 ns/op	       0 B/op	       0 allocs/op
BenchmarkArray-8       	20000000	       108 ns/op	       0 B/op	       0 allocs/op
BenchmarkFindIndex-8   	10000000	       125 ns/op	       0 B/op	       0 allocs/op
BenchmarkFindKey-8     	10000000	       125 ns/op	       0 B/op	       0 allocs/op
BenchmarkFindRange-8   	10000000	       186 ns/op	      16 B/op	       1 allocs/op
BenchmarkNumber-8      	50000000	        28.9 ns/op	       0 B/op	       0 allocs/op
BenchmarkObject-8      	20000000	        98.5 ns/op	       0 B/op	       0 allocs/op
BenchmarkString-8      	30000000	        40.4 ns/op	       0 B/op	       0 allocs/op

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