将json文件传递给GoLang函数

Question

Just getting started with Go.

I have a Go function as below to which I have to pass a json file. How can I pass a json file reference to this function i.e. accept it as a map of interfaces?

func compressOIds(mapDocument map[string]interface{}) string {
    var objectIdValue string
    for key, value := range mapDocument {
       ....
    }
    return ""
}

Answer 1

If the structure of your JSON is not well defined and can change, that's the way to go:

import (
    "fmt"
    "encoding/json"
)

func main() {
    var b = []byte(`{"a":"b", "c":1, "d": ["e", "f"]}`)
    var j map[string]interface{}
    err := json.Unmarshal(b, &j)
    if (err != nil) {
        return
    }

    printJson(j)
}

func printJson(j map[string]interface{}) {

    for k, v := range j {
        fmt.Printf("%v %v
", k, v)
    }
}

If your JSON is well defined, though, you can unmarshal it into struct, which is usually better:

import (
    "fmt"
    "encoding/json"
)

type Message struct {
    A string
    C int
    D []string
}

func main() {
    var b = []byte(`{"a":"b", "c":1, "d": ["e", "f"]}`)
    var j Message
    err := json.Unmarshal(b, &j)
    if (err != nil) {
        return
    }

    printJson(j)
}

func printJson(j Message) {
    fmt.Printf("A %v
", j.A)
    fmt.Printf("C %v
", j.C)
    fmt.Printf("D %v
", j.D)
}

You can play with later code here: https://play.golang.org/p/wDPy4m2x2_t