反向映射¶
当使用CQL过滤器对支持模板输出的层执行查询时，可以引用CQL表达式中的模板属性。插件将负责解释CQL过滤器，并在可能的情况下将其转换为数据源本地过滤器。例如，如果该数据源是关系数据库，则CQL过滤器将被转换为一个或多个SQL查询，这些查询将仅用于检索所需的数据。
请考虑以下GML输出示例：
<?xml version="1.0" encoding="UTF-8"?>
<wfs:FeatureCollection xmlns:wfs="http://www.opengis.net/wfs" xmlns:gml="http://www.opengis.net/gml" xmlns:st="http://www.stations.org/1.0" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" numberOfFeature="0" timeStamp="2021-07-16T08:38:50.735Z">
<gml:featureMember>
<st:MeteoStations gml:id="MeteoStationsFeature.7">
<st:code>Station_BOL</st:code>
<st:name>Bologna</st:name>
<st:geometry>
<gml:Point srsName="EPSG:4326" srsDimension="2">
<gml:pos>11.34 44.5</gml:pos>
</gml:Point>
</st:geometry>
<st:temperature>
<st:Temperature>
<st:time>2016-12-19T11:28:31.000Z</st:time>
<st:value>35.0</st:value>
</st:Temperature>
</st:temperature>
<st:temperature>
<st:Temperature>
<st:time>2016-12-19T11:28:55.000Z</st:time>
<st:value>25.0</st:value>
</st:Temperature>
</st:temperature>
<st:pressure>
<st:Pressure>
<st:time>2016-12-19T11:30:26.000Z</st:time>
<st:value>1019.0</st:value>
</st:Pressure>
</st:pressure>
<st:pressure>
<st:Pressure>
<st:time>2016-12-19T11:30:51.000Z</st:time>
<st:value>1015.0</st:value>
</st:Pressure>
</st:pressure>
<st:wind_speed>
<st:Wind_speed>
<st:time>2016-12-19T11:29:24.000Z</st:time>
<st:value>80.0</st:value>
</st:Wind_speed>
</st:wind_speed>
</st:MeteoStations>
</gml:featureMember>
<gml:featureMember>
<st:MeteoStations gml:id="MeteoStationsFeature.13">
<st:code>Station_ALS</st:code>
<st:name>Alessandria</st:name>
<st:geometry>
<gml:Point srsName="EPSG:4326" srsDimension="2">
<gml:pos>8.63 44.92</gml:pos>
</gml:Point>
</st:geometry>
<st:temperature>
<st:Temperature>
<st:time>2016-12-19T11:26:40.000Z</st:time>
<st:value>20.0</st:value>
</st:Temperature>
</st:temperature>
<st:wind_speed>
<st:Wind_speed>
<st:time>2016-12-19T11:27:13.000Z</st:time>
<st:value>155.0</st:value>
</st:Wind_speed>
</st:wind_speed>
</st:MeteoStations>
</gml:featureMember>
<gml:featureMember>
<st:MeteoStations gml:id="MeteoStationsFeature.21">
<st:code>Station_ROV</st:code>
<st:name>Rovereto</st:name>
<st:geometry>
<gml:Point srsName="EPSG:4326" srsDimension="2">
<gml:pos>11.05 45.89</gml:pos>
</gml:Point>
</st:geometry>
</st:MeteoStations>
</gml:featureMember>
</wfs:FeatureCollection>
以下是有效的CQL_Filters
st:name = 'Station_BOL'。st:temperature.st:Temperature.st:value < 25。
给定此基础GML模板：
<gft:Template>
<gft:Options>
<gft:Namespaces xmlns:st="http://www.stations.org/1.0"/>
</gft:Options>
<st:MeteoStations gml:id="${@id}">
<st:code>$${strConcat('Station_',st:code)}</st:code>
<st:name>${st:common_name}</st:name>
<st:geometry>${st:position}</st:geometry>
<st:temperature gft:isCollection="true" gft:source="st:meteoObservations/st:MeteoObservationsFeature" gft:filter="xpath('st:meteoParameters/st:MeteoParametersFeature/st:param_name') = 'temperature'">
<st:Temperature>
<st:time>${st:time}</st:time>
<st:value>${st:value}</st:value>
</st:Temperature>
</st:temperature>
<st:pressure gft:isCollection="true" gft:source="st:meteoObservations/st:MeteoObservationsFeature" gft:filter="xpath('st:meteoParameters/st:MeteoParametersFeature/st:param_name') = 'pressure'">
<st:Pressure>
<st:time>${st:time}</st:time>
<st:value>${st:value}</st:value>
</st:Pressure>
</st:pressure>
<st:wind_speed gft:isCollection="true" gft:source="st:meteoObservations/st:MeteoObservationsFeature" gft:filter="xpath('st:meteoParameters/st:MeteoParametersFeature/st:param_name') = 'wind speed'">
<st:Wind_speed>
<st:time>${st:time}</st:time>
<st:value>${st:value}</st:value>
</st:Wind_speed>
</st:wind_speed>
</st:MeteoStations>
</gft:Template>
上述cql_Filter将在内部转换为：
strConcat('Station_',st:code) = 'Station_BOL'。st:meteoObservations/st:MeteoObservationsFeature/st:MeteoParametersFeature/st:value < 25 AND st:meteoObservations/st:MeteoObservationsFeature/st:MeteoParametersFeature/st:param_name = 'temperature'。
从第二个示例中可以看出，如果为我们要作为筛选依据的值定义了模板筛选器，则该筛选器将自动包括在查询中。
向后映射功能可用于所有输出格式。考虑以下JSON-LD输出示例：
以下是有效CQL过滤器的示例：
Gsml：GeologicUnit.Description=‘某个字符串值’
(“麦西亚泥岩”，“UKNOWN”)
GSML：PositionalAccuracy.valueArray1=“100”
{
"@context": {
"gsp": "http://www.opengis.net/ont/geosparql#",
"sf": "http://www.opengis.net/ont/sf#",
"schema": "https://schema.org/",
"dc": "http://purl.org/dc/terms/",
"Feature": "gsp:Feature",
"FeatureCollection": "schema:Collection",
"Point": "sf:Point",
"wkt": "gsp:asWKT",
"features": {
"@container": "@set",
"@id": "schema:hasPart"
},
"geometry": "sf:geometry",
"description": "dc:description",
"title": "dc:title",
"name": "schema:name"
},
"type": "FeatureCollection",
"features": [
{
"@id": "mf2",
"@type": [
"Feature",
"gsml:MappedFeature",
"http://vocabulary.odm2.org/samplingfeaturetype/mappedFeature"
],
"name": "MERCIA MUDSTONE GROUP",
"gsml:positionalAccuracy":{
"value":"100",
"valueArray": ["100","someStaticVal"]
},
"gsml:GeologicUnit": {
"@id": "gu.25678",
"description": "Olivine basalt, tuff, microgabbro, minor sedimentary rocks",
"gsml:geologicUnitType": "urn:ogc:def:nil:OGC::unknown",
"gsml:composition": [
{
"gsml:compositionPart": [
{
"gsml:role": {
"value": "interbedded component",
"@codeSpace": "urn:cgi:classi..."
},
"proportion": {
"@dataType": "CGI_ValueProperty",
"CGI_TermValue": {
"@dataType": "CGI_TermValue",
"value": {
"value": "significant",
"@codeSpace": "some:uri"
}
}
},
"lithology": [
{
"@id": "cc.3",
"name": {
"value": "name_cc_3",
"@lang": "en"
},
"vocabulary": {
"@href": "urn:ogc:def:nil:OGC::missing"
}
}
]
}
]
},
{
"gsml:compositionPart": [
{
"gsml:role": {
"value": "interbedded component",
"@codeSpace": "urn:cgi:class..."
},
"proportion": {
"@dataType": "CGI_ValueProperty",
"CGI_TermValue": {
"@dataType": "CGI_TermValue",
"value": {
"value": "minor",
"@codeSpace": "some:uri"
}
}
},
"lithology": [
{
"@id": "cc.4",
"name": {
"value": "name_cc_4",
"@lang": "en"
},
"vocabulary": {
"@href": "urn:ogc:def:nil:OGC::missing"
}
}
]
}
]
}
],
"geometry": {
"@type": "Polygon",
"wkt": "POLYGON ((52.5 -1.3, 52.6 -1.3, 52.6 -1.2,...))"
}
}
}
]
}
以下是有效CQL过滤器的示例：
Gsml：GeologicUnit.Description=‘某个字符串值’
(“麦西亚泥岩”，“UKNOWN”)
GSML：PositionalAccuracy.valueArray1=“100”
如最后一个示例所示，要引用数组中列出简单属性的元素，需要从1开始的表单中的属性索引 {{attributeName}}{{index}} ，如 features.gsml:positionalAccuracy.valueArray1.
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