第Go中使用gjson來操作JSON數(shù)據(jù)的實現(xiàn)目錄獲取值路徑解析JSON行ResultType64-bitintegers讀取嵌套數(shù)組對象或數(shù)組迭代簡易的Parse和Get檢查value是否存在驗證JSON反序列化到map一次獲取多個值項目地址：/tidwall/gjson

下載：

$goget-u/tidwall/gjson

獲取值

Get查詢指定路徑,通過.來區(qū)分.比如name.last或者age.如果找到了匹配路徑,將返回結(jié)果.

packagemain

import"/tidwall/gjson"

constjson=`{"name":{"first":"Janet","last":"Prichard"},"age":47}`

funcmain(){

value:=gjson.Get(json,"name.last")

println(value.String())

輸出結(jié)果:

Prichard

同時有GetMany方法批量獲取值,也有GetBytes方法獲取字節(jié)切片.

路徑解析

路徑是一系列被.分隔的key拼接而成.路徑可能包含通配符*和.通過下標訪問數(shù)組值.通過#來獲取值在元素中的排位或訪問子路徑..和通配符可以通過來轉(zhuǎn)義.

{

"name":{"first":"Tom","last":"Anderson"},

"age":37,

"children":["Sara","Alex","Jack"],

"fav.movie":"DeerHunter",

"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"

"cildren.0""Sara"

"fav\.movie""DeerHunter"

"friends.#.first"["Dale","Roger","Jane"]

"friends.1.last""Craig"

你同樣能通過#[...]來查詢數(shù)組中的第一個匹配的項,或通過#[...]#查詢所有匹配的項.查詢支持==,!=,,=,,=比較運算符和%模糊匹配.

friends.#[last=="Murphy"].first"Dale"

friends.#[last=="Murphy"]#.first["Dale","Jane"]

friends.#[age45]#.last["Craig","Murphy"]

friends.#[first%"D*"].last"Murphy"

JSON行

同樣支持JSONLines,使用..前綴,把多行文檔視作數(shù)組.比如:

{"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"].age57

ForEachLines方法可以迭代json.

gjson.ForEachLine(json,func(linegjson.Result)bool{

println(line.String())

returntrue

ResultType

GJSON支持json類型包括string,number,bool,andnull.數(shù)組和對象被擋住基礎(chǔ)類型返回.Result持有如下其中一種類型:

bool,forJSONbooleans

float64,forJSONnumbers

string,forJSONstringliterals

nil,forJSONnull

直接訪問value:

result.Type//canbeString,Number,True,False,Null,orJSON

result.Str//holdsthestring

result.Num//holdsthefloat64number

result.Raw//holdstherawjson

result.Index//indexofrawvalueinoriginaljson,zeromeansindexunknown

有各種各樣的方便的函數(shù)可以獲取結(jié)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(pathstring)Result

result.ForEach(iteratorfunc(key,valueResult)bool)

result.Less(tokenResult,caseSensitivebool)bool

result.Value()方法返回interface{}Go基本類型之一.result.Array()方法返回一組值.如果結(jié)果是不存在的值,將會返回空數(shù)組.如果結(jié)果不是JSON數(shù)組,將會返回只包含一個值的數(shù)組.

booleanbool

numberfloat64

stringstring

nullnil

array[]interface{}

objectmap[string]interface{}

64-bitintegers

result.Int()和result.Uint()返回的是64位大數(shù)字.

result.Int()int64//-9223372036854775808to9223372036854775807

result.Uint()int64//0to18446744073709551615

讀取嵌套數(shù)組

假如你想從下列json獲取所有的lastName:

{

"programmers":[

"firstName":"Janet",

"lastName":"McLaughlin",

},{

"firstName":"Elliotte",

"lastName":"Hunter",

},{

"firstName":"Jason",

"lastName":"Harold",

你可以使用如下路徑programmers.#.lastName:

result:=gjson.Get(json,"programmers.#.lastName")

for_,name:=rangeresult.Array(){

println(name.String())

你同樣能獲取數(shù)組里的對象:

name:=gjson.Get(json,`programmers.#[lastName="Hunter"].firstName`)

println(name.String())//prints"Elliotte"

對象或數(shù)組迭代

ForEach方法允許你快速的迭代對象或數(shù)組.key和value被傳遞給對象的迭代器函數(shù).只有value被傳遞給數(shù)組.迭代器返回false將會終止迭代.

簡易的Parse和Get

Parse(json)方法可以簡單的分析json,result.Get(path)查詢結(jié)果.比如,下面的幾種情況都將返回相同的結(jié)果:

gjson.Parse(json).Get("name").Get("last")

gjson.Get(json,"name").Get("last")

gjson.Get(json,"name.last")

檢查value是否存在

有時你想要知道值是否存在.

value:=gjson.Get(json,"name.last")

if!value.Exists(){

println("nolastname")

}else{

println(value.String())

//Orasonestep

ifgjson.Get(json,"name.last").Exists(){

println("hasalastname")

驗證JSON

Get*和Parse*方法預(yù)期json格式是正常的,如果不正常,將會返回不可預(yù)料的結(jié)果.如果你讀取的json來源不可預(yù)料,那么你可以通過GJSON這么事先驗證.

if!gjson.Valid(json){

returnerrors.New("invalidjson")

value:=gjson.Get(json,"name.last")

反序列化到map

反序列化到map[string]interface{}:

m,ok:=gjson.Parse(json).Value().(map[string]interface{})

if!ok{

//notamap

##處理Bytes

如果你的JSON包含字節(jié)數(shù)組切片,與其調(diào)用`Get(string(data),path)`,不如調(diào)用[GetBytes](//tidwall/gjson#GetBytes)方法更優(yōu).

```go

varjson[]byte=...

result:=gjson.GetBytes(json,path)

如果你在使用gjson.GetBytes(json,path)方法,并且你想避免從result.Raw轉(zhuǎn)換到[]byte,你可以使用這種模式:

varjson[]byte=...

result:=gjson.GetBytes(json,path)

varraw[]byte

ifresult.Index0{

raw=json[result.Index:result.Index+len(result.Raw)]

}else{

raw=[]byte(result.Raw)