恐慌：json：如何在Golang中解组嵌套的JSON数组

huangapple
go评论119阅读模式
英文:

panic: json: How to unmarshall nested json array in Golang

问题

我遇到了一个解析嵌套JSON数组的问题。以下是示例：

  1. {
  2.   "Subnets": [
  3.     {
  4.       "AvailabilityZone": "xx",
  5.       "AvailabilityZoneId": "xx",
  6.       "AvailableIpAddressCount": 173,
  7.       "CidrBlock": "xx",
  8.       "DefaultForAz": "xx",
  9.       "MapPublicIpOnLaunch": "xx",
  10.       "MapCustomerOwnedIpOnLaunch": "xx",
  11.       "State": "xx",
  12.       "SubnetId": "xx",
  13.       "VpcId": "xx",
  14.       "OwnerId": "xx",
  15.       "AssignIpv6AddressOnCreation": "xx",
  16.       "Ipv6CidrBlockAssociationSet": [],
  17.       "Tags": [
  18.         {
  19.           "Key": "Name",
  20.           "Value": "xx"
  21.         },
  22.         {
  23.           "Key": "workload",
  24.           "Value": "xx"
  25.         },
  26.         {
  27.           "Key": "xx",
  28.           "Value": "xx"
  29.         },
  30.         {
  31.           "Key": "aws:cloudformation:stack-name",
  32.           "Value": "xx"
  33.         },
  34.         {
  35.           "Key": "host_support_group",
  36.           "Value": "xx"
  37.         },
  38.         {
  39.           "Key": "environment",
  40.           "Value": "xx"
  41.         },
  42.         {
  43.           "Key": "client",
  44.           "Value": "xx"
  45.         },
  46.         {
  47.           "Key": "aws:cloudformation:stack-id",
  48.           "Value": "xx"
  49.         },
  50.         {
  51.           "Key": "application",
  52.           "Value": "Subnet"
  53.         },
  54.         {
  55.           "Key": "xx",
  56.           "Value": "xx"
  57.         },
  58.         {
  59.           "Key": "xx",
  60.           "Value": "xx"
  61.         },
  62.         {
  63.           "Key": "xx",
  64.           "Value": "xx"
  65.         },
  66.         {
  67.           "Key": "regions",
  68.           "Value": "ca-central-1"
  69.         }
  70.       ],
  71.       "SubnetArn": "xx"
  72.     }
  73.   ],
  74.   "ResponseMetadata": {
  75.     "RequestId": "xx",
  76.     "HTTPStatusCode": 200,
  77.     "HTTPHeaders": {
  78.       "x-amzn-requestid": "xx",
  79.       "cache-control": "no-cache, no-store",
  80.       "strict-transport-security": "max-age=31536000; includeSubDomains",
  81.       "content-type": "text/xml;charset=UTF-8",
  82.       "content-length": "3176",
  83.       "vary": "accept-encoding",
  84.       "date": "xx",
  85.       "server": "AmazonEC2"
  86.     },
  87.     "RetryAttempts": 0
  88.   }
  89. }

我只想要"AvailableIpAddressCount"的值，我尝试使用interface{}，但无法获取所需的值。这是Golang playground的链接 - playground

错误-
我使用interface{}时遇到了这个错误

是否有其他方法可以从JSON对象中提取"AvailableIpAddressCount"的值？

感谢任何帮助或参考资料。

英文:

I'm having trouble unmarshalling a nested json array. Sample below:

  1. {
  2. "Subnets": [
  3. {
  4. "AvailabilityZone": "xx",
  5. "AvailabilityZoneId": "xx",
  6. "AvailableIpAddressCount": 173,
  7. "CidrBlock": "xx",
  8. "DefaultForAz": "xx",
  9. "MapPublicIpOnLaunch": "xx",
  10. "MapCustomerOwnedIpOnLaunch": "xx",
  11. "State": "xx",
  12. "SubnetId": "xx",
  13. "VpcId": "xx",
  14. "OwnerId": "xx",
  15. "AssignIpv6AddressOnCreation": "xx",
  16. "Ipv6CidrBlockAssociationSet": [],
  17. "Tags": [
  18. {
  19. "Key": "Name",
  20. "Value": "xx"
  21. },
  22. {
  23. "Key": "workload",
  24. "Value": "xx"
  25. },
  26. {
  27. "Key": "xx",
  28. "Value": "xx"
  29. },
  30. {
  31. "Key": "aws:cloudformation:stack-name",
  32. "Value": "xx"
  33. },
  34. {
  35. "Key": "host_support_group",
  36. "Value": "xx"
  37. },
  38. {
  39. "Key": "environment",
  40. "Value": "xx"
  41. },
  42. {
  43. "Key": "client",
  44. "Value": "xx"
  45. },
  46. {
  47. "Key": "aws:cloudformation:stack-id",
  48. "Value": "xx"
  49. },
  50. {
  51. "Key": "application",
  52. "Value": "Subnet"
  53. },
  54. {
  55. "Key": "xx",
  56. "Value": "xx"
  57. },
  58. {
  59. "Key": "xx",
  60. "Value": "xx"
  61. },
  62. {
  63. "Key": "xx",
  64. "Value": "xx"
  65. },
  66. {
  67. "Key": "regions",
  68. "Value": "ca-central-1"
  69. }
  70. ],
  71. "SubnetArn": "xx"
  72. }]
  73. ,
  74. "ResponseMetadata": {
  75. "RequestId": "xx",
  76. "HTTPStatusCode": 200,
  77. "HTTPHeaders": {
  78. "x-amzn-requestid": "xx",
  79. "cache-control": "no-cache, no-store",
  80. "strict-transport-security": "max-age=31536000; includeSubDomains",
  81. "content-type": "text/xml;charset=UTF-8",
  82. "content-length": "3176",
  83. "vary": "accept-encoding",
  84. "date": "xx",
  85. "server": "AmazonEC2"
  86. },
  87. "RetryAttempts": 0
  88. }
  89. }

The only value I want is "AvailableIpAddressCount", I tried using interface{} but I'm not able to get the necessary value. Here's the Golang playground link - playground

Error-
I'm getting this error using interface{}

Is there any other way to extract just the "AvailableIpAddressCount" value from the json object?

Any help or references are appreciated.

答案1

得分: 3

你可以创建一个具有所需字段的结构体，并使用该结构体解组JSON字节，这将填充结构体中提到的字段。

  1. type Something struct {
  2. 	AvailableIpAddressCount int `json:"AvailableIpAddressCount"`
  3. }
  5. var data Something
  6. if err := json.Unmarshal(byt, &data); err != nil {
  7.         panic(err)
  8. }
  10. AvailableIpAddressCount = data.AvailableIpAddressCount
英文:

You can create a struct with the desired field and unmarshal the JSON bytes using that struct which will populate fields mentioned in your struct.

  1. type Something struct {
  2. AvailableIpAddressCount int `json:"AvailableIpAddressCount"`
  3. }
  4. var data Something
  5. if err := json.unmarshal(byt, &data); err != nil {
  6. panic(err)
  7. }
  8. AvailableIpAddressCount = data.AvailableIpAddressCount

答案2

得分: 1

Go使用静态结构体来解码JSON，所以你可能需要创建一个包含至少你所需内容的结构体。如果你有了结构体，你可以像这样访问AvailableIPAddressCount：

  1. tmp.Subnets[0].AvailableIPAddressCount

这是一个示例代码的链接：https://play.golang.org/p/FsjeOubov1Q。

要从示例JSON创建JSON结构体，你可以使用像这个的工具。

如果你需要遍历所有子网：

  1. for _, subnet := range tmp.Subnets {
  2.     fmt.Println(subnet.AvailableIPAddressCount)
  3. }

如果你想动态使用JSON，你也可以使用https://github.com/spf13/viper。但它可能比静态解码慢。

英文:

Go uses static structs to decode json, so you probably need to create a struct that contains at least what you are looking for. If you have your struct, you can access AvailableIPAddressCount like this:

  1. tmp.Subnets[0].AvailableIPAddressCount

Here is the playground https://play.golang.org/p/FsjeOubov1Q.

To create json structs from example json you can use tools like this.

And if you need to loop through all subnets:

  1. for _, subnet := range tmp.Subnets {
  2. fmt.Println(subnet.AvailableIPAddressCount)
  3. }

If you want to use json dynamically you can also use https://github.com/spf13/viper. But it's probably slower than statically decoding.

huangapple
  • 本文由 发表于 2021年9月7日 17:02:03
  • 转载请务必保留本文链接：https://go.coder-hub.com/69085272.html
  • arrays
  • go
  • json
  • unmarshalling
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