Go language Json parsing utility tool-gjson

Golang beginners will definitely find Json parsing very troublesome. In fact, we need to change our thinking. We cannot directly convert Json into objects like PHP or JS.

So we define a series of functions to get the values ​​in Json.

gjson (github.com/tidwall/gjson) supports various Json operations very well. It can be used to easily parse Json, judge and obtain values.

2. Result structure

// First define a Result structure, which is the abstraction of all data
 type Result struct {
 Type Type // The type of this structure in Json
 Raw string // original json string
 Str string // string
 Num float64 // floating point number
 Index int // index
 }

 

3. Functions belonging to Result

func (t Result) Exists() bool // Determine whether a value exists
 func (t Result) Value() interface{} //
 func (t Result) Int() int64
 func (t Result) Uint() uint64
 func (t Result) Float() float64
 func (t Result) String() string
 func (t Result) Bool() bool
 func (t Result) Time() time.Time
 func (t Result) Array() []gjson.Result
 func (t Result) Map() map[string]gjson.Result
 func (t Result) Get(path string) Result
 func (t Result) ForEach(iterator func(key, value Result) bool) // Passable closure function
 func (t Result) Less(token Result, caseSensitive bool) bool
 

4. Initialization function

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

5. Determine whether Json is legal

if !gjson.Valid(json) {
 return errors.New("invalid json")
 }
 

3. Practical operation

1. Use

package main

 import (
 "fmt"
 "log"
 "strings"

 "github.com/tidwall/gjson"
 )

 const json = `{"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}]}`

 func main() {
 // First we determine whether the json is legal
 if !gjson.Valid(json) {
 log.Fatalf("%s", "invalid json")
 }
 // Get the age in Json
 age := gjson.Get(json, `age`).Int()
 fmt.Printf("%T, %+v\n", age, age)
 // Get lastname
 lastname := gjson.Get(json, `name.last`).String()
 fmt.Printf("%T, %+v\n", lastname, lastname)
 // Get the children array
 for _, v := range gjson.Get(json, `children`).Array() {
 fmt.Printf("%q ", v.String())
 }
 fmt.Println()
 // Get the second child
 fmt.Printf("%q\n", gjson.Get(json, `children.1`).String())
 fmt.Printf("%q\n", gjson.Get(json, `children|1`).String())
 // Wildcard to get the third child
 fmt.Printf("%q\n", gjson.Get(json, `child*.2`).String())
 //reverse array function
 fmt.Printf("%q\n", gjson.Get(json, `children|@reverse`).Array())
 // Custom function - convert all to uppercase
 gjson.AddModifier("case", func(json, arg string) string {
 if arg == "upper" {
 return strings.ToUpper(json)
 }
 return json
 })
 fmt.Printf("%+v\n", gjson.Get(json, `children|@case:upper`).Array())
 // Directly parse to map
 jsonMap := gjson.Parse(json).Map()
 fmt.Printf("%+v\n", jsonMap)
 for _, v := range jsonMap {
 fmt.Printf("%T, %+v\n", v, v)
 }
 }
 

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