Fixes #16706, categorized symbology matching lack of value is not properly encoded in SLD

Author: aaime

src/core/symbology/qgscategorizedsymbolrenderer.cpp

@@ -131,9 +131,20 @@ void QgsRendererCategory::toSld( QDomDocument &doc, QDomElement &element, QgsStr
   ruleElem.appendChild( descrElem );
 
   // create the ogc:Filter for the range
-  QString filterFunc = QStringLiteral( "%1 = '%2'" )
-                       .arg( attrName.replace( '\"', QLatin1String( "\"\"" ) ),
-                             mValue.toString().replace( '\'', QLatin1String( "''" ) ) );
+  QString filterFunc;
+  if ( mValue.isNull() || mValue.toString().isEmpty() )
+  {
+    filterFunc = QStringLiteral( "%1 = '%2' or %1 is null" )
+                 .arg( attrName.replace( '\"', QLatin1String( "\"\"" ) ),
+                       mValue.toString().replace( '\'', QLatin1String( "''" ) ) );
+  }
+  else
+  {
+    filterFunc = QStringLiteral( "%1 = '%2'" )
+                 .arg( attrName.replace( '\"', QLatin1String( "\"\"" ) ),
+                       mValue.toString().replace( '\'', QLatin1String( "''" ) ) );
+  }
+
   QgsSymbolLayerUtils::createFunctionElement( doc, ruleElem, filterFunc );
 
   // add the mix/max scale denoms if we got any from the callers

tests/src/python/test_qgssymbollayer_createsld.py

@@ -1195,6 +1195,23 @@ def assertVendorOption(self, container, expectedName, allowMissing=False):
         else:
             self.fail('Could not find a se:VendorOption named ' + expectedName + ' in ' + container.nodeName())
 
+    def testRuleBaseEmptyFilter(self):
+        layer = QgsVectorLayer("Point", "addfeat", "memory")
+
+        mFilePath = QDir.toNativeSeparators('%s/symbol_layer/%s.qml' % (unitTestDataPath(), "categorizedEmptyValue"))
+        status = layer.loadNamedStyle(mFilePath)  # NOQA
+
+        dom, root = self.layerToSld(layer)
+        # print("Rule based, with last rule checking against empty value:" + dom.toString())
+
+        # get the third rule
+        rule = root.elementsByTagName('se:Rule').item(2).toElement()
+        filter = rule.elementsByTagName('Filter').item(0).toElement()
+        filter = filter.firstChild().toElement()
+        self.assertEqual("ogc:Or", filter.nodeName())
+        self.assertEqual(1, filter.elementsByTagName('ogc:PropertyIsEqualTo').size())
+        self.assertEqual(1, filter.elementsByTagName('ogc:PropertyIsNull').size())
+
     def assertScaleDenominator(self, root, expectedMinScale, expectedMaxScale, index=0):
         rule = root.elementsByTagName('se:Rule').item(index).toElement()