GoLang Struct到JSON不转换

Question

This question already has an answer here:

• Why Golang cannot generate json from struct with front lowercase character? 1 answer

I am trying to convert my struct "Sim" into JSON, after being filled with data.

When I print the var s, it shows correct information, when I print data, it shows blank.

How do I convert Struct to JSON?

Reduced Code Below:

type Sim struct {
    yr, ag, av, db, wd, st []int
    withdrawal []string
}

func main() {
    // Creating simulation
    var s Sim

    // Filling with data
    s = simulate(15000, 60, 65, 90, 2015, 10.0, 140000.0, true, s)

    // Converting to JSON, for transmission over web
    data, err := json.Marshal(s)
    if err != nil {
        fmt.Println(err)
        return
    }

    // Data is correct
    fmt.Println(s)

    // Prints: {}
    fmt.Println(string(data))
}

</div>

Answer 1

Fields in your structures starts with lower case so they are not marshalled to JSON. Make them start with upper case letter.

package main

import "encoding/json"
import "fmt"

type Sim struct {
    Yr, Ag, Av, Db, Wd, St []int
    Withdrawal             []string
}

func main() {
    // Creating simulation
    var s Sim

    // Converting to JSON, for transmission over web
    data, err := json.Marshal(s)
    if err != nil {
        fmt.Println(err)
        return
    }

    // Data is correct
    fmt.Println(s)

    // Prints: {}
    fmt.Println(string(data))
}

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JSON serialization in GO