I have a polygon layer published in GeoServer through PostgreSQL (PostGIS) and I am trying to build a legend to use with GetLegendGraphich. The layer is requested as WMS layer in client with Leaflet on an Angular project.
My goal is to build a legend with properties 'fill' and 'fill-opacity' coming from the database (and not hard-coded in the style).
The layer is composed of following data:
- id (Integer)
- id_class (Integer)
- fill_color (String). It is a hexadecimal color code.
- fill_opacity (BigDecimal)
- geom (MultiPolygon)
The primary key is {id, id_class}. 'id' is used as a filter:
SELECT id, id_class, fill_color, fill_opacity, geom
FROM table
WHERE id = %id%
So far, I am using fields 'fill_color' and 'fill_opacity' to set the symbology in the layer's SLD style (but without any legend). Like this:
<NamedLayer>
<Name>layer_name</Name>
<UserStyle>
<Title>layer_title</Title>
<FeatureTypeStyle>
<Rule>
<Name>rule_name</Name>
<Title>rule_title</Title>
<PolygonSymbolizer>
<Fill>
<CssParameter name="fill-opacity">
<ogc:PropertyName>fill_opacity</ogc:PropertyName>
</CssParameter>
<CssParameter name="fill">
<ogc:PropertyName>fill_color</ogc:PropertyName>
</CssParameter>
</Fill>
<Stroke>
<CssParameter name="stroke">#000000</CssParameter>
<CssParameter name="stroke-width">0.2</CssParameter>
</Stroke>
</PolygonSymbolizer>
</Rule>
</FeatureTypeStyle>
</UserStyle>
</NamedLayer>
My goal is to build a legend like this one:
which I have built using the following SLD style:
<NamedLayer>
<Name>layer_name</Name>
<UserStyle>
<Title>legend</Title>
<FeatureTypeStyle>
<Rule>
<RasterSymbolizer>
<ChannelSelection>
<GrayChannel>
<SourceChannelName>1</SourceChannelName>
</GrayChannel>
</ChannelSelection>
<ColorMap type="values">
<ColorMapEntry label=" [a - b]" quantity="1" color="#32ce80"/>
<ColorMapEntry label=" (b - c]" quantity="2" color="#e3e926"/>
<ColorMapEntry label=" (c - d]" quantity="3" color="#e8ad15"/>
<ColorMapEntry label=" (d - e]" quantity="4" color="#ec0037"/>
<ColorMapEntry label=" > e" quantity="5" color="#a0009d"/>
</ColorMap>
</RasterSymbolizer>
</Rule>
</FeatureTypeStyle>
</UserStyle>
</NamedLayer>
So, I could use the first one (which uses PolygonSymbolizer properly) for symbology and the latter for producing a legend image (which would be a hack).
However, I would like to have one style: color + opacity coming from data fields (not hard-coded), and the legend.
I tried to separate each 'id_class' into a different rule, but could not make it work. The fill colors are not used in the legend:
<NamedLayer>
<Name>layer_name</Name>
<UserStyle>
<Title>layer_title</Title>
<FeatureTypeStyle>
<Rule>
<Name>class_1</Name>
<Title>[a - b]</Title>
<ogc:Filter>
<ogc:PropertyIsEqualTo>
<ogc:PropertyName>id_class</ogc:PropertyName>
<ogc:Literal>1</ogc:Literal>
</ogc:PropertyIsEqualTo>
</ogc:Filter>
<PolygonSymbolizer>
<Fill>
<CssParameter name="fill-opacity">
<ogc:PropertyName>fill_opacity</ogc:PropertyName>
</CssParameter>
<CssParameter name="fill">
<ogc:PropertyName>fill_color</ogc:PropertyName>
</CssParameter>
</Fill>
<Stroke>
<CssParameter name="stroke">#000000</CssParameter>
<CssParameter name="stroke-width">0.2</CssParameter>
</Stroke>
</PolygonSymbolizer>
</Rule>
<Rule>
<Name>class_2</Name>
<Title>(b - c]</Title>
<ogc:Filter>
<ogc:PropertyIsEqualTo>
<ogc:PropertyName>id_class</ogc:PropertyName>
<ogc:Literal>2</ogc:Literal>
</ogc:PropertyIsEqualTo>
</ogc:Filter>
<PolygonSymbolizer>
<Fill>
<CssParameter name="fill-opacity">
<ogc:PropertyName>fill_opacity</ogc:PropertyName>
</CssParameter>
<CssParameter name="fill">
<ogc:PropertyName>fill_color</ogc:PropertyName>
</CssParameter>
</Fill>
<Stroke>
<CssParameter name="stroke">#000000</CssParameter>
<CssParameter name="stroke-width">0.2</CssParameter>
</Stroke>
</PolygonSymbolizer>
</Rule>
<Rule>
<Name>class_3</Name>
<Title>(c - d]</Title>
<ogc:Filter>
<ogc:PropertyIsEqualTo>
<ogc:PropertyName>id_class</ogc:PropertyName>
<ogc:Literal>3</ogc:Literal>
</ogc:PropertyIsEqualTo>
</ogc:Filter>
<PolygonSymbolizer>
<Fill>
<CssParameter name="fill-opacity">
<ogc:PropertyName>fill_opacity</ogc:PropertyName>
</CssParameter>
<CssParameter name="fill">
<ogc:PropertyName>fill_color</ogc:PropertyName>
</CssParameter>
</Fill>
<Stroke>
<CssParameter name="stroke">#000000</CssParameter>
<CssParameter name="stroke-width">0.2</CssParameter>
</Stroke>
</PolygonSymbolizer>
</Rule>
<Rule>
<Name>class_4</Name>
<Title>(d - e]</Title>
<ogc:Filter>
<ogc:PropertyIsEqualTo>
<ogc:PropertyName>id_class</ogc:PropertyName>
<ogc:Literal>4</ogc:Literal>
</ogc:PropertyIsEqualTo>
</ogc:Filter>
<PolygonSymbolizer>
<Fill>
<CssParameter name="fill-opacity">
<ogc:PropertyName>fill_opacity</ogc:PropertyName>
</CssParameter>
<CssParameter name="fill">
<ogc:PropertyName>fill_color</ogc:PropertyName>
</CssParameter>
</Fill>
<Stroke>
<CssParameter name="stroke">#000000</CssParameter>
<CssParameter name="stroke-width">0.2</CssParameter>
</Stroke>
</PolygonSymbolizer>
</Rule>
<Rule>
<Name>class_5</Name>
<Title>> e</Title>
<ogc:Filter>
<ogc:PropertyIsEqualTo>
<ogc:PropertyName>id_class</ogc:PropertyName>
<ogc:Literal>5</ogc:Literal>
</ogc:PropertyIsEqualTo>
</ogc:Filter>
<PolygonSymbolizer>
<Fill>
<CssParameter name="fill-opacity">
<ogc:PropertyName>fill_opacity</ogc:PropertyName>
</CssParameter>
<CssParameter name="fill">
<ogc:PropertyName>fill_color</ogc:PropertyName>
</CssParameter>
</Fill>
<Stroke>
<CssParameter name="stroke">#000000</CssParameter>
<CssParameter name="stroke-width">0.2</CssParameter>
</Stroke>
</PolygonSymbolizer>
</Rule>
</FeatureTypeStyle>
</UserStyle>
</NamedLayer>
https://my_server/geoserver/wms?REQUEST=GetLegendGraphic&VERSION=1.0.0&FORMAT=image/png&LAYER=my_layer
Is there a way or I must use hard-coded fill color values?
