我是Go的新手,我正在构建一个使用Android应用程序中RDW数据的Web API.但是我在Go中解析JSON时遇到了麻烦,因为在Java中我可以很容易地使用类似的东西jsonObject.getString("AreaId").我似乎不能在Go中做到这一点.
我试图解析以下JSON以将其保存在MySQL数据库中:
{
'd': {
'results': [
{
'__metadata': {
'id': 'https://api.datamarket.azure.com/Data.ashx/opendata.rdw/StatischParkeren.Open.Data/v1/AREAGEOMETRY(1)',
'uri': 'https://api.datamarket.azure.com/Data.ashx/opendata.rdw/StatischParkeren.Open.Data/v1/AREAGEOMETRY(1)',
'type': 'opendata.rdw.StatischParkeren.Open.Data.AREAGEOMETRY'
},
'AREAGEOMETRY_ID': 1,
'AreaManagerId': '34',
'AreaId': 'ALMBUITEN',
'EndDateArea': null,
'StartDateArea': '/Date(1330560000000)/',
'AreaGeometryTxt': 'POLYGON ((5.2736760005354881 52.391216600313783, 5.2752534225583076 52.392331821843982, 5.2771425843238831 52.391448376700282, 5.2795117920336709 52.392518069183787, 5.2794937640428543 52.392529543489218, 5.2795250192284584 52.392524041235447, 5.2795117920336709 52.392518069183787, 5.27959094196558 52.392467692494392, 5.28429589420557 52.394528595730662, 5.2830820381641388 52.3958012573421, 5.2826158106327057 52.396464187651873, 5.28216527402401 52.396755328401923, 5.2811877280473709 52.396325327456, 5.27938649058342 52.395481485873461, 5.2793451324105263 52.395514352247119, 5.2788525596261024 52.395813956856728, 5.278492659330368 52.39611235447228, 5.2776647135615349 52.396820867434144, 5.2777034044265747 52.396853528916836, 5.2768759876489639 52.397581102326512, 5.274177111685276 52.396415254101157, 5.2741994857788086 52.396424867212772, 5.2686141580343246 52.394008679315448, 5.26860549300909 52.394005045294762, 5.2691666409373283 52.39350445382297, 5.2705547362565994 52.392721636220813, 5.2723518460904533 52.392156438032842, 5.2723518460989 52.39215643890202, 5.272359311580658 52.392154090106487, 5.2723518460904533 52.392156438032842, 5.2723498195409775 52.391947904601693, 5.273051455616951 52.391403153538704, 5.2736760005354881 52.391216600313783))',
'AreaGeometryGml': '<Polygon xmlns="http://www.opengis.net/gml"><exterior><LinearRing><posList>5.2736760005354881 52.391216600313783 5.2752534225583076 52.392331821843982 5.2771425843238831 52.391448376700282 5.2795117920336709 52.392518069183787 5.2794937640428543 52.392529543489218 5.2795250192284584 52.392524041235447 5.2795117920336709 52.392518069183787 5.27959094196558 52.392467692494392 5.28429589420557 52.394528595730662 5.2830820381641388 52.3958012573421 5.2826158106327057 52.396464187651873 5.28216527402401 52.396755328401923 5.2811877280473709 52.396325327456 5.27938649058342 52.395481485873461 5.2793451324105263 52.395514352247119 5.2788525596261024 52.395813956856728 5.278492659330368 52.39611235447228 5.2776647135615349 52.396820867434144 5.2777034044265747 52.396853528916836 5.2768759876489639 52.397581102326512 5.274177111685276 52.396415254101157 5.2741994857788086 52.396424867212772 5.2686141580343246 52.394008679315448 5.26860549300909 52.394005045294762 5.2691666409373283 52.39350445382297 5.2705547362565994 52.392721636220813 5.2723518460904533 52.392156438032842 5.2723518460989 52.39215643890202 5.272359311580658 52.392154090106487 5.2723518460904533 52.392156438032842 5.2723498195409775 52.391947904601693 5.273051455616951 52.391403153538704 5.2736760005354881 52.391216600313783</posList></LinearRing></exterior></Polygon>'
},
{
'__metadata': {
'id': 'https://api.datamarket.azure.com/Data.ashx/opendata.rdw/StatischParkeren.Open.Data/v1/AREAGEOMETRY(2)',
'uri': 'https://api.datamarket.azure.com/Data.ashx/opendata.rdw/StatischParkeren.Open.Data/v1/AREAGEOMETRY(2)',
'type': 'opendata.rdw.StatischParkeren.Open.Data.AREAGEOMETRY'
},
'AREAGEOMETRY_ID': 2,
'AreaManagerId': '34',
'AreaId': 'ALMTEGELZ',
'EndDateArea': null,
'StartDateArea': '/Date(1330560000000)/',
'AreaGeometryTxt': 'POLYGON ((5.216308925 52.370733155, 5.216800447 52.370804276, 5.216837124 52.370755791, 5.217178542 52.370807152, 5.217373999 52.370322534, 5.217353484 52.370319431, 5.217371539 52.370274734, 5.216664547 52.370167441, 5.216571837 52.370396589, 5.216451509 52.370380301, 5.216308925 52.370733155))',
'AreaGeometryGml': '<Polygon xmlns="http://www.opengis.net/gml"><exterior><LinearRing><posList>5.216308925 52.370733155 5.216800447 52.370804276 5.216837124 52.370755791 5.217178542 52.370807152 5.217373999 52.370322534 5.217353484 52.370319431 5.217371539 52.370274734 5.216664547 52.370167441 5.216571837 52.370396589 5.216451509 52.370380301 5.216308925 52.370733155</posList></LinearRing></exterior></Polygon>'
},
],
'__next': 'https://api.datamarket.azure.com/Data.ashx/opendata.rdw/StatischParkeren.Open.Data/v1/AREAGEOMETRY?$skiptoken=100'
}
}
这是我在Go中的代码:
type Data struct {
Next string
Results Result
}
type Result struct {
Results []AreaGeometry
}
type AreaGeometry struct {
AREAGEOMETRY_ID int32
AreaManagerId int64
AreaId string
EndDateArea string
StartDateArea string
AreaGeometryTxt string
}
// Synchronizes the AreaGeometry in our MySQL database with the AreaGeometry in the database from the RDW
func retrieveData() {
resp, err := http.Get("https://api.datamarket.azure.com/opendata.rdw/StatischParkeren.Open.Data/v1/AREAGEOMETRY?$format=json")
if err != nil {
panic(err.Error()) // TODO: proper error handling
}
body, err := ioutil.ReadAll(resp.Body)
var d Data
json.Unmarshal(body, &d)
fmt.Println("Next: " + d.Next)
}
但是,d.Next在解组后返回一个空字符串.我究竟做错了什么？什么是Go的照顾方式？
您需要使用JSON注释(在文档中称为struct"tags")来让它知道JSON中字段的名称:
type Data struct {
Next string `json:"__next"` //Field appears in JSON as key "__next".
Results Result `json:"results"`
}
我相信Go会自动处理resultsvs Results,但是如果你要发回数据并希望它是小写的,你仍然需要注释.
你Results Result的错误 - 结果不是Result类型的对象,它是一个AreaGeometry数组,所以它应该如下所示:
type Data struct {
Next string `json:"__next"` //Field appears in JSON as key "__next".
Results []AreaGeometry
}
此外,您需要JSON中的D对象的包装器:
type D struct {
D Data `json:"d"`
}
func main() {
body := jsonString //too long to put here, but in the playground.
var d D
err := json.Unmarshal([]byte(body), &d)
if (err != nil) {
fmt.Println(err)
}
fmt.Println("Next: " + d.D.Next)
}
http://play.golang.org/p/yK-zNxEMvy