Golang从结构数组中选择字段

Question

I get an array of all the users with an attribute ID in their document:

Users := []backend.User{}

err := Collection.Find(bson.M{"channel_id": bson.ObjectIdHex(chId)}).All(&Users)
if err != nil {
  println(err)
}

Which I want to send as a JSON response back to the browser/client. However, the User struct contains things like IDs and Hahsed Passwords which i don't want to send back!

I was looking at something like using the reflect package to select the fields of the struct and then putting them into a map[string]interface{} but im not sure how to do it with an array of users.

Answer 1

You can ignore struct fields while json.Marshal.

package main

import (
    "encoding/json"
    "fmt"
)

type User struct {
    Id   int    `json:"-"`
    Name string `json:"name"`
}

type Users []*User

func main() {

    user := &Users{
        &User{1, "Max"},
        &User{2, "Alice"},
        &User{3, "Dan"},
    }

    json, _ := json.Marshal(user)

    fmt.Println(string(json))
}

Runnable example in Play Golang: http://play.golang.org/p/AEC_TyXE3B

There is a very useful part about using the tags in the doc. Same for XML, but it's more complicated for obvious reasons.