在Go语言中获取内部JSON值

huangapple
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英文:

Get Inner JSON Value in Go

问题

我可以帮你翻译代码部分。以下是翻译的结果：

简单的问题，我在如何为JSON解码结构体的结构上遇到了困难。

如何将一个结构体的内部字段复制到另一个结构体的字段中？

我有以下JSON数据：

  1. {
  2.     "Trains": [{
  3.         "Car": "6",
  4.         "Destination": "SilvrSpg",
  5.         "DestinationCode": "B08",
  6.         "DestinationName": "Silver Spring",
  7.         "Group": "1",
  8.         "Line": "RD",
  9.         "LocationCode": "A13",
  10.         "LocationName": "Twinbrook",
  11.         "Min": "1"
  12.     }]
  13. }

我有以下结构体：

  1. type Trains struct {
  2.   Min      string `json:"Min"`
  3.   DestName string `json:"DestinationName"`
  4.   DestCode string `json:"DestinationCode"`
  5.   LocName  string `json:"LocationName"`
  6.   LocCode  string `json:"LocationCode"`
  7.   Line     string `json:"Line"`
  8. }
  10. type AllData struct {
  11.   Data []Trains `json:"Trains"`
  12. }

我如何将Trains.LocationCode的值复制到类似以下结构体的位置：

  1. type AllData struct {
  2.   Id   string   `json:"Id"`
  3.   Data []Trains `json:"Trains"`
  4. }

所以，我基本上只需要有以下JSON结构：

  1. {
  2.     "Id": "A13",
  3.     "Data": [{
  4.         "Car": "6",
  5.         "Destination": "SilvrSpg",
  6.         "DestinationCode": "B08",
  7.         "DestinationName": "Silver Spring",
  8.         "Group": "1",
  9.         "Line": "RD",
  10.         "LocationCode": "A13",
  11.         "LocationName": "Twinbrook",
  12.         "Min": "1"
  13.     }]
  14. }

其中，Id是Trains结构体的内部值。

你想要如何构造一个结构体来反映这个结构？

英文:

Simple question that I'm having a difficult time how to structure a struct for JSON decoding.

How can I copy an inner field of a struct to another field of a struct?

I have JSON

  1. {
  2.     "Trains": [{
  3.         "Car": "6",
  4.         "Destination": "SilvrSpg",
  5.         "DestinationCode": "B08",
  6.         "DestinationName": "Silver Spring",
  7.         "Group": "1",
  8.         "Line": "RD",
  9.         "LocationCode": "A13",
  10.         "LocationName": "Twinbrook",
  11.         "Min": "1"
  12.     }]
  13. }

And I have structs

  1. type Trains struct {
  2.   Min      string `json:"Min"`
  3.   DestName string `json:"DestinationName"`
  4.   DestCode string `json:"DestinationCode"`
  5.   LocName  string `json:"LocationName"`
  6.   LocCode  string `json:"LocationCode"`
  7.   Line     string `json:"Line"`
  8. }
  10. type AllData struct {
  11.   Data []Trains `json:"Trains"`
  12. }

How Can I get the value of the Trains.LocationCode to a struct like

  1. type AllData struct {
  2.   Id Trains[0].LocCode value
  3.   Data []Trains `json:"Trains"`
  4. }

So I basically just need to have JSON like this

  1. {
  2.     "Id":"A13",
  3.     "Data": [{
  4.         "Car": "6",
  5.         "Destination": "SilvrSpg",
  6.         "DestinationCode": "B08",
  7.         "DestinationName": "Silver Spring",
  8.         "Group": "1",
  9.         "Line": "RD",
  10.         "LocationCode": "A13",
  11.         "LocationName": "Twinbrook",
  12.         "Min": "1"
  13.     }]
  14. }

Where the Id is the inner value of the Trains struct.

How can I structure a struct to reflect this?

答案1

得分: 0

JSON解码器没有这个功能。您必须在您的应用程序中编写这行代码。

  1. package main
  3. import (
  4.     "encoding/json"
  5.     "fmt"
  6.     "log"
  7. )
  9. var s = `
  10. {
  11.     "Trains": [{
  12.         "Car": "6",
  13.         "Destination": "SilvrSpg",
  14.         "DestinationCode": "B08",
  15.         "DestinationName": "Silver Spring",
  16.         "Group": "1",
  17.         "Line": "RD",
  18.         "LocationCode": "A13",
  19.         "LocationName": "Twinbrook",
  20.         "Min": "1"
  21.     }]
  22. }`
  24. type Train struct {
  25.     Min      string `json:"Min"`
  26.     DestName string `json:"DestinationName"`
  27.     DestCode string `json:"DestinationCode"`
  28.     LocName  string `json:"LocationName"`
  29.     LocCode  string `json:"LocationCode"`
  30.     Line     string `json:"Line"`
  31. }
  33. type Data struct {
  34.     // The name "-" tells the JSON decoder to ignore this field.
  35.     ID     string `json:"-"`
  36.     Trains []Train
  37. }
  39. func main() {
  40.     var d Data
  41.     if err := json.Unmarshal([]byte(s), &d); err != nil {
  42.         log.Fatal(err)
  43.     }
  44.     if len(d.Trains) < 1 {
  45.         log.Fatal("No trains")
  46.     }
  47.     // Copy value from inner to outer.
  48.     d.ID = d.Trains[0].LocCode
  49.     fmt.Printf("%+v\n", d)
  50. }
英文:

The JSON decoder does not have this capability. You must write the line of code in your application.

  1. package main
  3. import (
  4.     &quot;encoding/json&quot;
  5.     &quot;fmt&quot;
  6.     &quot;log&quot;
  7. )
  9. var s = `
  10. {
  11.     &quot;Trains&quot;: [{
  12.         &quot;Car&quot;: &quot;6&quot;,
  13.         &quot;Destination&quot;: &quot;SilvrSpg&quot;,
  14.         &quot;DestinationCode&quot;: &quot;B08&quot;,
  15.         &quot;DestinationName&quot;: &quot;Silver Spring&quot;,
  16.         &quot;Group&quot;: &quot;1&quot;,
  17.         &quot;Line&quot;: &quot;RD&quot;,
  18.         &quot;LocationCode&quot;: &quot;A13&quot;,
  19.         &quot;LocationName&quot;: &quot;Twinbrook&quot;,
  20.         &quot;Min&quot;: &quot;1&quot;
  21.     }]
  22. }`
  24. type Train struct {
  25.     Min      string `json:&quot;Min&quot;`
  26.     DestName string `json:&quot;DestinationName&quot;`
  27.     DestCode string `json:&quot;DestinationCode&quot;`
  28.     LocName  string `json:&quot;LocationName&quot;`
  29.     LocCode  string `json:&quot;LocationCode&quot;`
  30.     Line     string `json:&quot;Line&quot;`
  31. }
  33. type Data struct {
  34.     // The name &quot;-&quot; tells the JSON decoder to ignore this field.
  35.     ID     string `json:&quot;-&quot;`
  36.     Trains []Train
  37. }
  39. func main() {
  40.     var d Data
  41.     if err := json.Unmarshal([]byte(s), &amp;d); err != nil {
  42.         log.Fatal(err)
  43.     }
  44.     if len(d.Trains) &lt; 1 {
  45.         log.Fatal(&quot;No trains&quot;)
  46.     }
  47.     // Copy value from inner to outer.
  48.     d.ID = d.Trains[0].LocCode
  49.     fmt.Printf(&quot;%+v\n&quot;, &amp;d)
  50. }

huangapple
  • 本文由 发表于 2014年9月17日 23:15:14
  • 转载请务必保留本文链接：https://go.coder-hub.com/25894352.html
  • go
  • json
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