[FEATURE][processing] add discard non matching option to join attribu…

…te table alg

python/plugins/processing/tests/testdata/expected/join_attribute_table_discard_nonmatching.gfs

@@ -0,0 +1,41 @@
+<GMLFeatureClassList>
+  <GMLFeatureClass>
+    <Name>join_attribute_table</Name>
+    <ElementPath>join_attribute_table</ElementPath>
+    <GeometryType>1</GeometryType>
+    <SRSName>EPSG:4326</SRSName>
+    <DatasetSpecificInfo>
+      <FeatureCount>1</FeatureCount>
+      <ExtentXMin>0.00000</ExtentXMin>
+      <ExtentXMax>8.00000</ExtentXMax>
+      <ExtentYMin>-5.00000</ExtentYMin>
+      <ExtentYMax>3.00000</ExtentYMax>
+    </DatasetSpecificInfo>
+    <PropertyDefn>
+      <Name>id</Name>
+      <ElementPath>id</ElementPath>
+      <Type>Integer</Type>
+    </PropertyDefn>
+    <PropertyDefn>
+      <Name>id2</Name>
+      <ElementPath>id2</ElementPath>
+      <Type>Integer</Type>
+    </PropertyDefn>
+    <PropertyDefn>
+      <Name>id_2</Name>
+      <ElementPath>id_2</ElementPath>
+      <Type>Integer</Type>
+    </PropertyDefn>
+    <PropertyDefn>
+      <Name>NUM_A</Name>
+      <ElementPath>NUM_A</ElementPath>
+      <Type>Real</Type>
+    </PropertyDefn>
+    <PropertyDefn>
+      <Name>ST_A</Name>
+      <ElementPath>ST_A</ElementPath>
+      <Type>String</Type>
+      <Width>8</Width>
+    </PropertyDefn>
+  </GMLFeatureClass>
+</GMLFeatureClassList>

python/plugins/processing/tests/testdata/expected/join_attribute_table_discard_nonmatching.gml

@@ -0,0 +1,24 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<ogr:FeatureCollection
+     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+     xsi:schemaLocation=""
+     xmlns:ogr="http://ogr.maptools.org/"
+     xmlns:gml="http://www.opengis.net/gml">
+  <gml:boundedBy>
+    <gml:Box>
+      <gml:coord><gml:X>0</gml:X><gml:Y>-5</gml:Y></gml:coord>
+      <gml:coord><gml:X>8</gml:X><gml:Y>3</gml:Y></gml:coord>
+    </gml:Box>
+  </gml:boundedBy>
+
+  <gml:featureMember>
+    <ogr:join_attribute_table fid="points.0">
+      <ogr:geometryProperty><gml:Point srsName="EPSG:4326"><gml:coordinates>1,1</gml:coordinates></gml:Point></ogr:geometryProperty>
+      <ogr:id>1</ogr:id>
+      <ogr:id2>2</ogr:id2>
+      <ogr:id_2>1</ogr:id_2>
+      <ogr:NUM_A>1.100000</ogr:NUM_A>
+      <ogr:ST_A>string a</ogr:ST_A>
+    </ogr:join_attribute_table>
+  </gml:featureMember>
+</ogr:FeatureCollection>

python/plugins/processing/tests/testdata/qgis_algorithm_tests.yaml

@@ -2788,6 +2788,24 @@ tests:
         name: expected/join_attribute_table.gml
         type: vector
 
+  - algorithm: native:joinattributestable
+    name: join the attribute table by common field, discard non matching (one-to-one)
+    params:
+      METHOD: 0
+      INPUT:
+        name: points.gml
+        type: vector
+      INPUT_2:
+        name: table2.dbf
+        type: table
+      FIELD: id
+      FIELD_2: ID
+      DISCARD_NONMATCHING: true
+    results:
+      OUTPUT:
+        name: expected/join_attribute_table_discard_nonmatching.gml
+        type: vector
+
   - algorithm: native:joinattributestable
     name: join the attribute table by common field (one-to-many)
     params:

src/analysis/processing/qgsalgorithmjoinbyattribute.cpp

@@ -26,12 +26,12 @@ QString QgsJoinByAttributeAlgorithm::name() const
 
 QString QgsJoinByAttributeAlgorithm::displayName() const
 {
-  return QObject::tr( "Join attributes table" );
+  return QObject::tr( "Join attributes by field value" );
 }
 
 QStringList QgsJoinByAttributeAlgorithm::tags() const
 {
-  return QObject::tr( "join,connect,attributes,values,fields" ).split( ',' );
+  return QObject::tr( "join,connect,attributes,values,fields,tables" ).split( ',' );
 }
 
 QString QgsJoinByAttributeAlgorithm::group() const
@@ -65,10 +65,12 @@ void QgsJoinByAttributeAlgorithm::initAlgorithm( const QVariantMap & )
                 QVariant(), QStringLiteral( "INPUT_2" ), QgsProcessingParameterField::Any,
                 true, true ) );
 
-  addParameter( new QgsProcessingParameterEnum(
-                  QStringLiteral( "METHOD" ),
-                  QObject::tr( "Join type" ),
-                  methods, false, 0 ) );
+  addParameter( new QgsProcessingParameterEnum( QStringLiteral( "METHOD" ),
+                QObject::tr( "Join type" ),
+                methods, false, 0 ) );
+  addParameter( new QgsProcessingParameterBoolean( QStringLiteral( "DISCARD_NONMATCHING" ),
+                QObject::tr( "Discard records which could not be joined" ),
+                false ) );
 
   addParameter( new QgsProcessingParameterFeatureSink( QStringLiteral( "OUTPUT" ), QObject::tr( "Joined layer" ) ) );
 }
@@ -78,8 +80,7 @@ QString QgsJoinByAttributeAlgorithm::shortHelpString() const
   return QObject::tr( "This algorithm takes an input vector layer and creates a new vector layer that is an extended version of the "
                       "input one, with additional attributes in its attribute table.\n\n"
                       "The additional attributes and their values are taken from a second vector layer. An attribute is selected "
-                      "in each of them to define the join criteria.\n\n"
-                      "The algorithm will output one feature per matching row(s) from the second vector layer." );
+                      "in each of them to define the join criteria." );
 }
 
 QgsJoinByAttributeAlgorithm *QgsJoinByAttributeAlgorithm::createInstance() const
@@ -90,6 +91,7 @@ QgsJoinByAttributeAlgorithm *QgsJoinByAttributeAlgorithm::createInstance() const
 QVariantMap QgsJoinByAttributeAlgorithm::processAlgorithm( const QVariantMap &parameters, QgsProcessingContext &context, QgsProcessingFeedback *feedback )
 {
   int joinMethod = parameterAsEnum( parameters, QStringLiteral( "METHOD" ), context );
+  bool discardNonMatching = parameterAsBool( parameters, QStringLiteral( "DISCARD_NONMATCHING" ), context );
 
   std::unique_ptr< QgsFeatureSource > input( parameterAsSource( parameters, QStringLiteral( "INPUT" ), context ) );
   std::unique_ptr< QgsFeatureSource > input2( parameterAsSource( parameters, QStringLiteral( "INPUT_2" ), context ) );
@@ -199,7 +201,7 @@ QVariantMap QgsJoinByAttributeAlgorithm::processAlgorithm( const QVariantMap &pa
         sink->addFeature( feat, QgsFeatureSink::FastInsert );
       }
     }
-    else
+    else if ( !discardNonMatching )
     {
       sink->addFeature( feat, QgsFeatureSink::FastInsert );
     }