How to check string is in json format

Question

I want to create a function to receive an input string which can be string in json format or just a string. For example, something easy like following function.

func checkJson(input string){    if ... input is in json ... {       fmt.Println("it's json!")    } else {       fmt.Println("it's normal string!")    } } 

Answer 1

For anyone else looking for a way to validate any JSON string regardless of schema, try the following:

func IsJSON(str string) bool {     var js json.RawMessage     return json.Unmarshal([]byte(str), &js) == nil } 

Answer 2

I was unclear if you needed to know about just a "quoted string" or if you needed to know about json, or the difference between both of them, so this shows you how to detect both scenarios so you can be very specific.

I posted the interactive code sample here as well: http://play.golang.org/p/VmT0BVBJZ7

package main  import (     "encoding/json"     "fmt" )  func isJSONString(s string) bool {     var js string     return json.Unmarshal([]byte(s), &js) == nil  }  func isJSON(s string) bool {     var js map[string]interface{}     return json.Unmarshal([]byte(s), &js) == nil  }  func main() {     var tests = []string{         `"Platypus"`,         `Platypus`,         `{"id":"1"}`,     }      for _, t := range tests {         fmt.Printf("isJSONString(%s) = %v\n", t, isJSONString(t))         fmt.Printf("isJSON(%s) = %v\n\n", t, isJSON(t))     }  } 

Which will output this:

isJSONString("Platypus") = true isJSON("Platypus") = false  isJSONString(Platypus) = false isJSON(Platypus) = false  isJSONString({"id":"1"}) = false isJSON({"id":"1"}) = true