go JSON和struct的转换 2021-09-04

golang JSON和struct的转换，[]byte作为中介

• Json to struct:

  json string -> []byte -> struct

  其中，[]byte -> struct这一步use json.Unmarshal(data []byte, v interface{})

  • json.Unmarshal 到 map

    package main
    
    import "fmt"
    import "encoding/json"
    
    func main () {
      s := "{\"abc\":1}"
      var data = map[string]int{"ab":2}
      err := json.Unmarshal(([]byte)(s), &data)
      if err != nil {
          fmt.Println(err)
          return
      }
      fmt.Println(data)
    }
    >>>
    map[ab:2 abc:1]  // 不影响原来的k v
    

    package main
    
    import "fmt"
    import "encoding/json"
    
    func main () {
      s := "{\"abc\":1}"
      var data = map[string]int{"abc":2}
      err := json.Unmarshal(([]byte)(s), &data)
      if err != nil {
          fmt.Println(err)
          return
      }
      fmt.Println(data)
    }
    >>>
    map[abc:1]  // 覆盖原有k v
    

  • json.Unmarshal 到 slice

    package main
    
    import "fmt"
    import "encoding/json"
    
    func main () {
      s := "[\"abc\",1]"
      var data = []interface{}{"ab",2}
      fmt.Println("ori data is ", data)
      err := json.Unmarshal(([]byte)(s), &data)
      if err != nil {
          fmt.Println(err)
          return
      }
      fmt.Println("after unmarshal data is ", data)
    }
    >>>
    ori data is  [ab 2]
    after unmarshal data is  [abc 1]  // unmarshal到slice会先清空再写入
    

• struct to JSON:

  struct -> []byte -> json string

  其中，struct -> []byte这一步use json.Marshal(v interface{})

• More info see: https://sanyuesha.com/2018/05/07/go-json/