目录
  • 获取值
  • 路径解析
  • JSON 行
  • Result Type
    • 64-bit integers
    • 读取嵌套数组
  • 对象或数组迭代
  • 简易的Parse和Get
  • 检查value是否存在
  • 验证JSON
  • 反序列化到map
  • 一次获取多个值

项目地址：https://github.com/tidwall/gjson

下载：

$ go get -u github.com/tidwall/gjson

获取值

.
package main
import "github.com/tidwall/gjson"
const json = `{"name":{"first":"Janet","last":"Prichard"},"age":47}`
func main() {
    value := gjson.Get(json, "name.last")
    println(value.String())
}

输出结果:

Prichard

同时有 GetMany 方法批量获取值, 也有 GetBytes 方法获取字节切片.

路径解析

..
{
  "name": {"first": "Tom", "last": "Anderson"},
  "age":37,
  "children": ["Sara","Alex","Jack"],
  "fav.movie": "Deer Hunter",
  "friends": [
    {"first": "Dale", "last": "Murphy", "age": 44},
    {"first": "Roger", "last": "Craig", "age": 68},
    {"first": "Jane", "last": "Murphy", "age": 47}
  ]
}

"name.last"          >> "Anderson"
"age"                >> 37
"children"           >> ["Sara","Alex","Jack"]
"children.#"         >> 3
"children.1"         >> "Alex"
"child*.2"           >> "Jack"
"c?ildren.0"         >> "Sara"
"fav.movie"         >> "Deer Hunter"
"friends.#.first"    >> ["Dale","Roger","Jane"]
"friends.1.last"     >> "Craig"

#[...]==!=<<=>>=
friends.#[last=="Murphy"].first    >> "Dale"
friends.#[last=="Murphy"]#.first   >> ["Dale","Jane"]
friends.#[age>45]#.last            >> ["Craig","Murphy"]
friends.#[first%"D*"].last         >> "Murphy"

JSON 行

..
{"name": "Gilbert", "age": 61}
{"name": "Alexa", "age": 34}
{"name": "May", "age": 57}
{"name": "Deloise", "age": 44}

..#                   >> 4
..1                   >> {"name": "Alexa", "age": 34}
..3                   >> {"name": "Deloise", "age": 44}
..#.name              >> ["Gilbert","Alexa","May","Deloise"]
..#[name="May"].age   >> 57

ForEachLines
gjson.ForEachLine(json, func(line gjson.Result) bool{
    println(line.String())
    return true
})

Result Type

stringnumberboolnullResult
bool, for JSON booleans
float64, for JSON numbers
string, for JSON string literals
nil, for JSON null

直接访问value:

result.Type    // can be String, Number, True, False, Null, or JSON
result.Str     // holds the string
result.Num     // holds the float64 number
result.Raw     // holds the raw json
result.Index   // index of raw value in original json, zero means index unknown

有各种各样的方便的函数可以获取结果:

result.Exists() bool
result.Value() interface{}
result.Int() int64
result.Uint() uint64
result.Float() float64
result.String() string
result.Bool() bool
result.Time() time.Time
result.Array() []gjson.Result
result.Map() map[string]gjson.Result
result.Get(path string) Result
result.ForEach(iterator func(key, value Result) bool)
result.Less(token Result, caseSensitive bool) bool

result.Value()interface{}result.Array()
boolean >> bool
number  >> float64
string  >> string
null    >> nil
array   >> []interface{}
object  >> map[string]interface{}

64-bit integers

result.Int()result.Uint()
result.Int() int64    // -9223372036854775808 to 9223372036854775807
result.Uint() int64   // 0 to 18446744073709551615

读取嵌套数组

假如你想从下列json获取所有的lastName:

{
  "programmers": [
    {
      "firstName": "Janet", 
      "lastName": "McLaughlin", 
    }, {
      "firstName": "Elliotte", 
      "lastName": "Hunter", 
    }, {
      "firstName": "Jason", 
      "lastName": "Harold", 
    }
  ]
}

programmers.#.lastName
result := gjson.Get(json, "programmers.#.lastName")
for _, name := range result.Array() {
    println(name.String())
}

你同样能获取数组里的对象:

name := gjson.Get(json, `programmers.#[lastName="Hunter"].firstName`)
println(name.String())  // prints "Elliotte"

对象或数组迭代

ForEachfalse

简易的Parse和Get

Parse(json)result.Get(path)
gjson.Parse(json).Get("name").Get("last")
gjson.Get(json, "name").Get("last")
gjson.Get(json, "name.last")

检查value是否存在

有时你想要知道值是否存在.

value := gjson.Get(json, "name.last")
if !value.Exists() {
    println("no last name")
} else {
    println(value.String())
}
// Or as one step
if gjson.Get(json, "name.last").Exists() {
    println("has a last name")
}

验证JSON

Get*Parse*
if !gjson.Valid(json) {
    return errors.New("invalid json")
}
value := gjson.Get(json, "name.last")

反序列化到map

map[string]interface{}
m, ok := gjson.Parse(json).Value().(map[string]interface{})
if !ok {
    // not a map
}
## 处理Bytes
如果你的JSON包含字节数组切片, 与其调用`Get(string(data), path)`, 不如调用[GetBytes](https://godoc.org/github.com/tidwall/gjson#GetBytes)方法更优.
```go
var json []byte = ...
result := gjson.GetBytes(json, path)

gjson.GetBytes(json, path)result.Raw[]byte
var json []byte = ...
result := gjson.GetBytes(json, path)
var raw []byte
if result.Index > 0 {
    raw = json[result.Index:result.Index+len(result.Raw)]
} else {
    raw = []byte(result.Raw)
}

result.Indexresult.Raw[]byteresult.Index

一次获取多个值

GetMany
results := gjson.GetMany(json, "name.first", "name.last", "age")

[]Result