使用 golang 解组 GML 时出错 encoding/xml

Error unmarshalling GML with golang encoding/xml

我正在尝试解组一些 XML,实际上是地理标记语言 (GML)。

我在 http://play.golang.org/p/qS6GjCOtHF

有一个例子

两个问题,第一个:

error reading xml main.FeatureCollection field "LowerCorner" with tag "boundedBy>Envelope>lowerCorner" conflicts with field "Envelope" with tag "boundedBy>Envelope"

我不知道如何解决这个问题。我评论了那些并让 GML 无错误地解组但是 FeatureCollection.

中没有 Features

有什么线索吗?

GML 的一个例子是:

<?xml version="1.0" encoding="UTF-8"?>
<gml:FeatureCollection xmlns:gml="http://www.opengis.net/gml"
    xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:fme="http://www.safe.com/gml/fme" xsi:schemaLocation="http://www.safe.com/gml/fme tblMainGML.xsd">
    <gml:boundedBy>
        <gml:Envelope srsName="EPSG:3112" srsDimension="2">
            <gml:lowerCorner>45.2921142578125 -80.2166748046875</gml:lowerCorner>
            <gml:upperCorner>169.000122070313 -9.14251708984375</gml:upperCorner>
        </gml:Envelope>
    </gml:boundedBy>
    <gml:featureMember>
        <fme:GML gml:id="id5255fa48-42b3-43d1-9e0d-b2ba8b57a936">
            <fme:OBJECTID>1</fme:OBJECTID>
            <fme:RECORD_ID>QLD48234</fme:RECORD_ID>
            <fme:NAME>HATCHMAN POINT</fme:NAME>
            <fme:FEAT_CODE>PT</fme:FEAT_CODE>
            <fme:CGDN>N</fme:CGDN>
            <fme:AUTHORITY_ID>QLD</fme:AUTHORITY_ID>
            <fme:CONCISE_GAZ>N</fme:CONCISE_GAZ>
            <fme:LATITUDE>-12.58361</fme:LATITUDE>
            <fme:lat_degrees>-12</fme:lat_degrees>
            <fme:lat_minutes>35</fme:lat_minutes>
            <fme:lat_seconds>0</fme:lat_seconds>
            <fme:LONGITUDE>141.62583</fme:LONGITUDE>
            <fme:long_degrees>141</fme:long_degrees>
            <fme:long_minutes>37</fme:long_minutes>
            <fme:long_seconds>32</fme:long_seconds>
            <fme:STATE_ID>QLD</fme:STATE_ID>
            <fme:STATUS>U</fme:STATUS>
            <fme:VARIANT_NAME />
            <fme:MAP_100K>7272</fme:MAP_100K>
            <fme:Place_ID>45880</fme:Place_ID>
            <gml:pointProperty>
                <gml:Point srsName="EPSG:3112" srsDimension="2">
                    <gml:pos>141.625915527344 -12.5836181640625</gml:pos>
                </gml:Point>
            </gml:pointProperty>
        </fme:GML>
    </gml:featureMember>
</gml:FeatureCollection>
</xml>

我的结构

type FeatureCollection struct {
    Xsi            string   `xml:"xsi,attr"`
    Fme            string   `xml:"fme,attr"`
    Gml            string   `xml:"gml,attr"`
    Xlink          string   `xml:"xlink,attr"`
    LowerCorner    string   `xml:"boundedBy>Envelope>lowerCorner"`
    UpperCorner    string   `xml:"boundedBy>Envelope>upperCorner"`
    Envelope       Envelope `xml:"boundedBy>Envelope"`
    SchemaLocation string   `xml:"schemaLocation,attr"`
    Features       []Feature
}

type Feature struct {
    PlaceID     string `xml:"featureMember>GML>Place_ID"`
    StateID     string `xml:"featureMember>GML>STATE_ID"`
    Postcode    string `xml:"featureMember>GML>POSTCODE"`
    CGDN        string `xml:"featureMember>GML>CGDN"`
    Map100K     string `xml:"featureMember>GML>MAP_100K"`
ETC...
}

一个XML标签只能映射到(至多)一个结构字段。 encoding/xml 包必须决定每个 XML 标签将被解码到哪个结构字段。您为 XML 建模的结构很奇怪,并使这个决定变得模棱两可。

举个例子:

type FeatureCollection struct {
    ...
    LowerCorner    string   `xml:"boundedBy>Envelope>lowerCorner"`
    UpperCorner    string   `xml:"boundedBy>Envelope>upperCorner"`
    Envelope       Envelope `xml:"boundedBy>Envelope"`
    ...
}

encoding/xml 包无法决定 XML 标签 <Envelope> 应该被解码到哪里,例如进入 LowerCorner?进入 UpperCorner?进入 Envelope?是的,我知道 LowerCorner 只是 <Envelope> 的子元素,但由于整个 <Envelope> 元素映射到 FeatureCollection.Envelope,这是不允许的。

您应该将 LowerCornerUpperCorner 字段移动到您的 Envelope 结构类型中,因为那是它们所属的位置并且您想要解组整个 Envelope xml 标签(或者如果没有, FeatureCollection.Envelope 可以完全删除)。因此,请按照此模式将字段放在它们所属的位置。

这是您更新后的模型,它提取了您想要的所有信息:

type FeatureCollection struct {
    Xsi            string   `xml:"xsi,attr"`
    Fme            string   `xml:"fme,attr"`
    Gml            string   `xml:"gml,attr"`
    Xlink          string   `xml:"xlink,attr"`
    Envelope       Envelope `xml:"boundedBy>Envelope"`
    SchemaLocation string   `xml:"schemaLocation,attr"`
    FeaturesGML    []GML    `xml:"featureMember>GML"`
}
type Envelope struct {
    SrsName      string `xml:"srsName,attr"`
    SrsDimension string `xml:"srsDimension,attr"`
    LowerCorner  string `xml:"lowerCorner"`
    UpperCorner  string `xml:"upperCorner"`
}
type GML struct {
    ID          string `xml:"id,attr"`
    PlaceID     string `xml:"Place_ID"`
    StateID     string `xml:"STATE_ID"`
    Postcode    string `xml:"POSTCODE"`
    CGDN        string `xml:"CGDN"`
    Map100K     string `xml:"MAP_100K"`
    Point       Point  `xml:"pointProperty>Point"`
    VariantName string `xml:"VARIANT_NAME"`
    RecordID    string `xml:"RECORD_ID"`
    LatSeconds  string `xml:"lat_seconds"`
    Status      string `xml:"STATUS"`
    LongSeconds string `xml:"long_seconds"`
    ConciseGAZ  string `xml:"CONCISE_GAZ"`
    Lattitude   string `xml:"LATITUDE"`
    AuthorityID string `xml:"AUTHORITY_ID"`
    Longitude   string `xml:"LONGITUDE"`
    LongMinutes string `xml:"long_minutes"`
    LatDegrees  string `xml:"lat_degrees"`
    NAME        string `xml:"NAME"`
    LatMinutes  string `xml:"lat_minutes"`
    ObjectID    string `xml:"OBJECTID"`
    FeatCode    string `xml:"FEAT_CODE"`
    LongDegrees string `xml:"long_degrees"`
}
type Point struct {
    SrsName      string `xml:"srsName,attr"`
    SrsDimension string `xml:"srsDimension,attr"`
    Pos          string `xml:"pos"`
}

这是您在 Go Playground 上的代码的修改版本,运行时没有错误。

验证您的结构是否包含来自 XML 的所有未编组信息:

fmt.Printf("%+v", v)

输出:

&{Xsi:http://www.w3.org/2001/XMLSchema-instance Fme:http://www.safe.com/gml/fme Gml:http://www.opengis.net/gml Xlink:http://www.w3.org/1999/xlink Envelope:{SrsName:EPSG:3112 SrsDimension:2 LowerCorner:45.2921142578125 -80.2166748046875 UpperCorner:169.000122070313 -9.14251708984375} SchemaLocation:http://www.safe.com/gml/fme tblMainGML.xsd FeaturesGML:[{ID:id5255fa48-42b3-43d1-9e0d-b2ba8b57a936 PlaceID:45880 StateID:QLD Postcode: CGDN:N Map100K:7272 Point:{SrsName:EPSG:3112 SrsDimension:2 Pos:141.625915527344 -12.5836181640625} VariantName: RecordID:QLD48234 LatSeconds:0 Status:U LongSeconds:32 ConciseGAZ:N Lattitude:-12.58361 AuthorityID:QLD Longitude:141.62583 LongMinutes:37 LatDegrees:-12 NAME:HATCHMAN POINT LatMinutes:35 ObjectID:1 FeatCode:PT LongDegrees:141}]}