json - 使用标准模板包从json对象获取前两个值

Question

来自api的json响应是这样的

{
  "ResponseCode": "1",
  "Response": "Data Found",
  "data": [
    {
      "Season": "KHARIF",
      "Sector": "AGRICULTURE",
      "Category": "Cereals",
      "Crop": "Paddy (Dhan)",
      "QueryType": "\tField Preparation\t",
      "QueryText": "top dressing for paddy",
      "KccAns": "top dressing for paddy : apply urea 25kg+SSP 15kg +  neem cake 5kg+MN mixture 5kg mixed with 40kg of sand",
      "StateName": "PUDUCHERRY",
      "DistrictName": "KARAIKAL",
      "BlockName": "KARAIKAL",
      "CreatedOn": "1/5/2014 6:48:09 PM"
    },
    {
      "Season": "KHARIF",
      "Sector": "AGRICULTURE",
      "Category": "Others",
      "Crop": "Others",
      "QueryType": "Weather",
      "QueryText": "weather forecasting details",
      "KccAns": "today no rain",
      "StateName": "PUDUCHERRY",
      "DistrictName": "KARAIKAL",
      "BlockName": "KARAIKAL",
      "CreatedOn": "1/5/2014 9:04:50 PM"
    },
    {
      "Season": "KHARIF",
      "Sector": "AGRICULTURE",
      "Category": "Others",
      "Crop": "Others",
      "QueryType": "0",
      "QueryText": "details about soil testing",
      "KccAns": "contact to agricultural department",
      "StateName": "PUDUCHERRY",
      "DistrictName": "KARAIKAL",
      "BlockName": "KARAIKAL",
      "CreatedOn": "1/8/2014 10:21:18 AM"
    },
    {
      "Season": "KHARIF",
      "Sector": "AGRICULTURE",
      "Category": "Cereals",
      "Crop": "Paddy (Dhan)",
      "QueryType": "Fertilizer Use and Availability",
      "QueryText": "paddy top dressing fertilizer",
      "KccAns": "apply urea 25 kg + potash 15 kg + neem cake 5 kg + microfood 5 kg / ac",
      "StateName": "PUDUCHERRY",
      "DistrictName": "KARAIKAL",
      "BlockName": "KARAIKAL",
      "CreatedOn": "1/12/2014 8:01:45 AM"
    }
  ]
}

我正在尝试编写一个golang模板，该模板仅返回响应对象的data部分中的前两个数据点。这是我目前正在使用的模板 {{range $element := .data}} {{$element}} {{end}}，但这将返回.data领域中的所有子数据。我该如何做这个锻炼。

Answer 1

如果您的go版本至少为go1.13，则可以使用slice模板函数获取前两个元素。例子:

{{$dataSliced := slice .data 0 2}}
{{range $element := $dataSliced}}
    {{$element}}
{{end}}

对于旧版本的go，可以通过使用 range和 if lt关键字获得相同的结果。例子:

{{range $index, $element := .data}}
    {{if lt $index 2}}
        {{$element}}
    {{end}}
{{end}}

或者，您也可以为 slice 创建自定义模板功能。

有关模板功能的更多信息: https://golang.org/pkg/text/template。