json.Marshal(struct) 返回“{}”
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json.Marshal(struct) returns "{}"
提问by Doug Knesek
type TestObject struct {
kind string `json:"kind"`
id string `json:"id, omitempty"`
name string `json:"name"`
email string `json:"email"`
}
func TestCreateSingleItemResponse(t *testing.T) {
testObject := new(TestObject)
testObject.kind = "TestObject"
testObject.id = "f73h5jf8"
testObject.name = "Yuri Gagarin"
testObject.email = "[email protected]"
fmt.Println(testObject)
b, err := json.Marshal(testObject)
if err != nil {
fmt.Println(err)
}
fmt.Println(string(b[:]))
}
Here is the output:
这是输出：
[ `go test -test.run="^TestCreateSingleItemResponse$"` | done: 2.195666095s ]
{TestObject f73h5jf8 Yuri Gagarin [email protected]}
{}
PASS
Why is the JSON essentially empty?
为什么 JSON 本质上是空的？
回答by Cerise Limón
You need to exportthe fields in TestObject by capitalizing the first letter in the field name. Change kindto Kindand so on.
您需要通过将字段名称中的第一个字母大写来导出TestObject 中的字段。更改kind为Kind等等。
type TestObject struct {
Kind string `json:"kind"`
Id string `json:"id,omitempty"`
Name string `json:"name"`
Email string `json:"email"`
}
The encoding/json package and similar packages ignore unexported fields.
encoding/json 包和类似的包会忽略未导出的字段。
The `json:"..."`strings that follow the field declarations are struct tags. The tags in this struct set the names of the struct's fields when marshaling to and from JSON.
`json:"..."`字段声明后面的字符串是struct tags。在与 JSON 之间进行封送处理时，此结构中的标签设置结构字段的名称。
回答by Sourabh Bhagat
- When the first letter is capitalised, the identifier is public to any piece of code that you want to use.
- When the first letter is lowercase, the identifier is private and could only be accessed within the package it was declared.
- 当第一个字母大写时，标识符对您要使用的任何代码段都是公开的。
- 当第一个字母是小写时，标识符是私有的，只能在它声明的包内访问。
Examples
例子
var aName // private
var BigBro // public (exported)
var 123abc // illegal
func (p *Person) SetEmail(email string) { // public because SetEmail() function starts with upper case
p.email = email
}
func (p Person) email() string { // private because email() function starts with lower case
return p.email
}
回答by superup
In golang
在 golang
in struct first letter must uppercase ex. phonenumber -> PhoneNumber
在 struct 中的第一个字母必须大写，例如。电话号码 -> 电话号码
======= Add detail
======== 添加细节
First, I'm try coding like this
首先，我尝试这样编码
type Questions struct {
id string
questionDesc string
questionID string
ans string
choices struct {
choice1 string
choice2 string
choice3 string
choice4 string
}
}
golang compile is not error and not show warning. But response is empty because something
golang compile 不是错误并且不显示警告。但响应是空的，因为某事
After that, I search google found this article
之后，我搜索谷歌找到了这篇文章
Struct Types and Struct Type Literals Articlethen... I try edit code.
结构类型和结构类型文字 文章然后...我尝试编辑代码。
//Questions map field name like database
type Questions struct {
ID string
QuestionDesc string
QuestionID string
Ans string
Choices struct {
Choice1 string
Choice2 string
Choice3 string
Choice4 string
}
}
Is work.
是工作。
Hope for help.
希望得到帮助。
