Add option to include 'layer' and 'path' attributes in Merge Vector L…

…ayers tool (qgis#55397)

Add option to include layer name and path in 'Merge Vector Layers' tool.The option is enabled by default to maintain backward compatibility.This modification addresses issue qgis#55397 by providing users with greater control over the attributes included in the merged output, enhancing the flexibility and usability of the tool.

Fixes qgis#55397

src/analysis/processing/qgsalgorithmmergevector.cpp

@@ -17,7 +17,7 @@
 
 #include "qgsalgorithmmergevector.h"
 #include "qgsvectorlayer.h"
-
+#include "qgsprocessingparameters.h"
 ///@cond PRIVATE
 
 QString QgsMergeVectorAlgorithm::name() const
@@ -50,6 +50,9 @@ void QgsMergeVectorAlgorithm::initAlgorithm( const QVariantMap & )
   addParameter( new QgsProcessingParameterMultipleLayers( QStringLiteral( "LAYERS" ), QObject::tr( "Input layers" ), Qgis::ProcessingSourceType::Vector ) );
   addParameter( new QgsProcessingParameterCrs( QStringLiteral( "CRS" ), QObject::tr( "Destination CRS" ), QVariant(), true ) );
   addParameter( new QgsProcessingParameterFeatureSink( QStringLiteral( "OUTPUT" ), QObject::tr( "Merged" ) ) );
+
+  // new boolean parameter to add source layer information
+  addParameter( new QgsProcessingParameterBoolean( QStringLiteral( "ADD_SOURCE_FIELDS" ), QObject::tr( "Add source layer information (layer name and path)" ), true ) );
 }
 
 QString QgsMergeVectorAlgorithm::shortDescription() const
@@ -62,7 +65,7 @@ QString QgsMergeVectorAlgorithm::shortHelpString() const
   return QObject::tr( "This algorithm combines multiple vector layers of the same geometry type into a single one.\n\n"
                       "The attribute table of the resulting layer will contain the fields from all input layers. "
                       "If fields with the same name but different types are found then the exported field will be automatically converted into a string type field. "
-                      "New fields storing the original layer name and source are also added.\n\n"
+                      "Optionally, new fields storing the original layer name and source can be added.\n\n"
                       "If any input layers contain Z or M values, then the output layer will also contain these values. Similarly, "
                       "if any of the input layers are multi-part, the output layer will also be a multi-part layer.\n\n"
                       "Optionally, the destination coordinate reference system (CRS) for the merged layer can be set. If it is not set, the CRS will be "
@@ -83,6 +86,8 @@ QVariantMap QgsMergeVectorAlgorithm::processAlgorithm( const QVariantMap &parame
 {
   const QList<QgsMapLayer *> layers = parameterAsLayerList( parameters, QStringLiteral( "LAYERS" ), context );
 
+  const bool addSourceFields = parameterAsBool( parameters, QStringLiteral( "ADD_SOURCE_FIELDS" ), context );
+
   QgsFields outputFields;
   long totalFeatureCount = 0;
   Qgis::WkbType outputType = Qgis::WkbType::Unknown;
@@ -184,16 +189,20 @@ QVariantMap QgsMergeVectorAlgorithm::processAlgorithm( const QVariantMap &parame
   }
 
   bool addLayerField = false;
-  if ( outputFields.lookupField( QStringLiteral( "layer" ) ) < 0 )
-  {
-    outputFields.append( QgsField( QStringLiteral( "layer" ), QMetaType::Type::QString, QString() ) );
-    addLayerField = true;
-  }
   bool addPathField = false;
-  if ( outputFields.lookupField( QStringLiteral( "path" ) ) < 0 )
+  if ( addSourceFields ) // add source layer information
   {
-    outputFields.append( QgsField( QStringLiteral( "path" ), QMetaType::Type::QString, QString() ) );
-    addPathField = true;
+    if ( outputFields.lookupField( QStringLiteral( "layer" ) ) < 0 )
+    {
+      outputFields.append( QgsField( QStringLiteral( "layer" ), QMetaType::Type::QString, QString() ) );
+      addLayerField = true;
+    }
+
+    if ( outputFields.lookupField( QStringLiteral( "path" ) ) < 0 )
+    {
+      outputFields.append( QgsField( QStringLiteral( "path" ), QMetaType::Type::QString, QString() ) );
+      addPathField = true;
+    }
   }
 
   QString dest;