Gabs is a small utility for dealing with dynamic or unknown JSON structures in golang. It's pretty much just a helpful wrapper around the golang json.Marshal/json.Unmarshal behaviour and map[string]interface{} objects. It does nothing spectacular except for being fabulous.

https://godoc.org/github.com/Jeffail/gabs

How to install:

go get github.com/Jeffail/gabs

How to use

Parsing and searching JSON

...

import "github.com/Jeffail/gabs"

jsonParsed, err := gabs.ParseJSON([]byte(`{
	"outter":{
		"inner":{
			"value1":10,
			"value2":22
		},
		"alsoInner":{
			"value1":20
		}
	}
}`))

var value float64
var ok bool

value, ok = jsonParsed.Path("outter.inner.value1").Data().(float64)
// value == 10.0, ok == true

value, ok = jsonParsed.Search("outter", "inner", "value1").Data().(float64)
// value == 10.0, ok == true

value, ok = jsonParsed.Path("does.not.exist").Data().(float64)
// value == 0.0, ok == false

exists := jsonParsed.Exists("outter", "inner", "value1")
// exists == true

exists := jsonParsed.Exists("does", "not", "exist")
// exists == false

exists := jsonParsed.ExistsP("does.not.exist")
// exists == false

...

Iterating objects

...

jsonParsed, _ := gabs.ParseJSON([]byte(`{"object":{ "first": 1, "second": 2, "third": 3 }}`))

// S is shorthand for Search
children, _ := jsonParsed.S("object").ChildrenMap()
for key, child := range children {
	fmt.Printf("key: %v, value: %v\n", key, child.Data().(string))
}

...

Iterating arrays

...

jsonParsed, _ := gabs.ParseJSON([]byte(`{"array":[ "first", "second", "third" ]}`))

// S is shorthand for Search
children, _ := jsonParsed.S("array").Children()
for _, child := range children {
	fmt.Println(child.Data().(string))
}

...

Will print:

first
second
third

Children() will return all children of an array in order. This also works on objects, however, the children will be returned in a random order.

Searching through arrays

If your JSON structure contains arrays you can still search the fields of the objects within the array, this returns a JSON array containing the results for each element.

...

jsonParsed, _ := gabs.ParseJSON([]byte(`{"array":[ {"value":1}, {"value":2}, {"value":3} ]}`))
fmt.Println(jsonParsed.Path("array.value").String())

...

Will print:

[1,2,3]

Generating JSON

...

jsonObj := gabs.New()
// or gabs.Consume(jsonObject) to work on an existing map[string]interface{}

jsonObj.Set(10, "outter", "inner", "value")
jsonObj.SetP(20, "outter.inner.value2")
jsonObj.Set(30, "outter", "inner2", "value3")

fmt.Println(jsonObj.String())

...

Will print:

{"outter":{"inner":{"value":10,"value2":20},"inner2":{"value3":30}}}

To pretty-print:

...

fmt.Println(jsonObj.StringIndent("", "  "))

...

Will print:

{
  "outter": {
    "inner": {
      "value": 10,
      "value2": 20
    },
    "inner2": {
      "value3": 30
    }
  }
}

Generating Arrays

...

jsonObj := gabs.New()

jsonObj.Array("foo", "array")
// Or .ArrayP("foo.array")

jsonObj.ArrayAppend(10, "foo", "array")
jsonObj.ArrayAppend(20, "foo", "array")
jsonObj.ArrayAppend(30, "foo", "array")

fmt.Println(jsonObj.String())

...

Will print:

{"foo":{"array":[10,20,30]}}

Working with arrays by index:

...

jsonObj := gabs.New()

// Create an array with the length of 3
jsonObj.ArrayOfSize(3, "foo")

jsonObj.S("foo").SetIndex("test1", 0)
jsonObj.S("foo").SetIndex("test2", 1)

// Create an embedded array with the length of 3
jsonObj.S("foo").ArrayOfSizeI(3, 2)

jsonObj.S("foo").Index(2).SetIndex(1, 0)
jsonObj.S("foo").Index(2).SetIndex(2, 1)
jsonObj.S("foo").Index(2).SetIndex(3, 2)

fmt.Println(jsonObj.String())

...

Will print:

{"foo":["test1","test2",[1,2,3]]}

Converting back to JSON

This is the easiest part:

...

jsonParsedObj, _ := gabs.ParseJSON([]byte(`{
	"outter":{
		"values":{
			"first":10,
			"second":11
		}
	},
	"outter2":"hello world"
}`))

jsonOutput := jsonParsedObj.String()
// Becomes `{"outter":{"values":{"first":10,"second":11}},"outter2":"hello world"}`

...

And to serialize a specific segment is as simple as:

...

jsonParsedObj := gabs.ParseJSON([]byte(`{
	"outter":{
		"values":{
			"first":10,
			"second":11
		}
	},
	"outter2":"hello world"
}`))

jsonOutput := jsonParsedObj.Search("outter").String()
// Becomes `{"values":{"first":10,"second":11}}`

...

Parsing Numbers

Gabs uses the json package under the bonnet, which by default will parse all number values into float64. If you need to parse Int values then you should use a json.Decoder (https://golang.org/pkg/encoding/json/#Decoder):

sample := []byte(`{"test":{"int":10, "float":6.66}}`)
dec := json.NewDecoder(bytes.NewReader(sample))
dec.UseNumber()

val, err := gabs.ParseJSONDecoder(dec)
if err != nil {
    t.Errorf("Failed to parse: %v", err)
    return
}

intValue, err := val.Path("test.int").Data().(json.Number).Int64()