XML Marshal 在此 Go 示例中不起作用

Question

在此代码中，returned 元素 x 没有正文 - 我认为 MarshalIndent 无法正常工作。我将无法使用 struct Record。是否有任何变通方法可以 return 预期的值。

package main

import "fmt"
import "encoding/xml"
import "time"

type Record struct {
    a int64     `xml:"a,omitempty"`
    b int64     `xml:"b,omitempty"`
    c int64     `xml:"c,omitempty"`
    d int64     `xml:"d,omitempty"`
    e int64     `xml:"e,omitempty"`
    f string    `xml:"f,omitempty"`
    g string    `xml:"g,omitempty"`
    h string    `xml:"h,omitempty"`
    i string    `xml:"i,omitempty"`
    j string    `xml:"j,omitempty"`
    k time.Time `xml:"k,omitempty"`
    l time.Time `xml:"l,omitempty"`
    m string    `xml:"m,omitempty"`
    n string    `xml:"n,omitempty"`
    o string    `xml:"o,omitempty"`
    p int64     `xml:"p,omitempty"`
}

func main() {
    temp, _ := time.Parse(time.RFC3339, "")
    candiateXML := &Record{1, 2, 3, 4, 5, "6", "7", "8", "9", "10", temp, temp, "13", "14", "15", 16}
    fmt.Printf("%v\n", candiateXML.a)
    fmt.Printf("%v\n", candiateXML.b)
    fmt.Printf("%v\n", candiateXML.c)
    fmt.Printf("%v\n", candiateXML.d)
    fmt.Printf("%v\n", candiateXML.e)
    fmt.Printf("%s\n", candiateXML.f)
    fmt.Printf("%s\n", candiateXML.g)
    fmt.Printf("%s\n", candiateXML.h)
    fmt.Printf("%s\n", candiateXML.i)
    fmt.Printf("%s\n", candiateXML.j)
    fmt.Printf("%d\n", candiateXML.k)
    fmt.Printf("%d\n", candiateXML.l)
    fmt.Printf("%s\n", candiateXML.m)
    fmt.Printf("%s\n", candiateXML.n)
    fmt.Printf("%s\n", candiateXML.o)
    fmt.Printf("%v\n", candiateXML.p)

    x, err := xml.MarshalIndent(candiateXML, "", "  ")
    if err != nil {
        return
    }
    //why this is not printing properly
    fmt.Printf("%s\n", x)
}

MarshalIndent 没有return预期的结果。

Answer 1

The Go Programming Language Specification

Exported identifiers

An identifier may be exported to permit access to it from another package. An identifier is exported if both:

the first character of the identifier's name is a Unicode upper case letter (Unicode class "Lu"); and

the identifier is declared in the package block or it is a field name or method name.

All other identifiers are not exported.

导出您的 Record 结构字段名称（第一个字符大写）以允许从 xml 包访问它们。例如，

package main

import "fmt"
import "encoding/xml"

type Record struct {
    A int64 `xml:"a,omitempty"`
    B int64 `xml:"b,omitempty"`
    C int64 `xml:"c,omitempty"`
}

func main() {
    candiateXML := &Record{1, 2, 3}
    fmt.Printf("%v\n", candiateXML.A)
    fmt.Printf("%v\n", candiateXML.B)
    fmt.Printf("%v\n", candiateXML.C)

    x, err := xml.MarshalIndent(candiateXML, "", "  ")
    if err != nil {
        return
    }
    fmt.Printf("%s\n", x)
}

输出：

1
2
3
<Record>
  <a>1</a>
  <b>2</b>
  <c>3</c>
</Record>

XML Marshal 在此 Go 示例中不起作用

XML Marshal not working in this Go example

xml

marshalling

go