go - 有没有一种好方法可以不在 json 有效负载中公开某些结构属性？

Question

我真的希望下面的代码能工作，但现在不行，所以我必须手动将值从一个结构设置到另一个结构。

https://play.golang.org/p/yfcsaNJm9M

package main

import "fmt"
import "encoding/json"

type A struct {
    Name     string `json:"name"`
    Password string `json:"password"`
}

type B struct {
    A
    Password string `json:"-"`
    Locale   string `json:"locale"`
}

func main() {

    a := A{"Jim", "some_secret_password"}
    b := B{A: a, Locale: "en"}

    data, _ := json.Marshal(&b)
    fmt.Printf("%v", string(data))
}

输出...我不想显示 secret 字段

{"name":"Jim","password":"some_secret_password","locale":"en"}

Answer 1

Struct values encode as JSON objects. Each exported struct field becomes a member of the object unless

- the field's tag is "-", or
- the field is empty and its tag specifies the "omitempty" option.

The empty values are false, 0, any nil pointer or interface value, and any array, slice, map, or string of length zero. The object's default key string is the struct field name but can be specified in the struct field's tag value. The "json" key in the struct field's tag value is the key name, followed by an optional comma and options. Examples:

// Field is ignored by this package.
Field int `json:"-"`

// Field appears in JSON as key "myName".
Field int `json:"myName"`

// Field appears in JSON as key "myName" and
// the field is omitted from the object if its value is     empty,
// as defined above.
Field int `json:"myName,omitempty"`

// Field appears in JSON as key "Field" (the default), but
// the field is skipped if empty.
// Note the leading comma.
Field int `json:",omitempty"`

所以你的代码应该是:

package main

import "fmt"
import "encoding/json"

type A struct {
    Name     string `json:"name"`
    Password string `json:"password"`
}

type B struct {
    A
    Password string `json:"password,omitempty"`
    Locale   string `json:"locale"`
}

func main() {

    a := A{"Jim", "some_secret_password"}
    b := B{A: a, Locale: "en"}

    data, _ := json.Marshal(&b)
    fmt.Printf("%v", string(data))
}

https://play.golang.org/p/HdwIssr-oC