Handle mixed lists of values and lists when evaluating multilayer

parameters

This can happen when running models with mixed input types
for multilayer parameters

src/core/processing/qgsprocessingparameters.cpp

@@ -22,6 +22,7 @@
 #include "qgsprocessingoutputs.h"
 #include "qgssettings.h"
 #include "qgsvectorfilewriter.h"
+#include <functional>
 
 bool QgsProcessingParameters::isDynamic( const QVariantMap &parameters, const QString &name )
 {
@@ -596,31 +597,36 @@ QList<QgsMapLayer *> QgsProcessingParameters::parameterAsLayerList( const QgsPro
 
   QStringList resultStringList;
 
-  if ( val.canConvert<QgsProperty>() )
-    resultStringList << val.value< QgsProperty >().valueAsString( context.expressionContext(), definition->defaultValue().toString() );
-  else if ( val.type() == QVariant::List )
+  std::function< void( const QVariant &var ) > processVariant;
+  processVariant = [ &resultStringList, &layers, &context, &definition, &processVariant ]( const QVariant & var )
   {
-    Q_FOREACH ( const QVariant &var, val.toList() )
+    if ( var.type() == QVariant::List )
     {
-      if ( QgsMapLayer *layer = qobject_cast< QgsMapLayer * >( qvariant_cast<QObject *>( var ) ) )
+      Q_FOREACH ( const QVariant &listVar, var.toList() )
       {
-        layers << layer;
+        processVariant( listVar );
       }
-      else
+    }
+    else if ( var.type() == QVariant::StringList )
+    {
+      Q_FOREACH ( const QString &s, var.toStringList() )
       {
-        resultStringList << var.toString();
+        resultStringList << s;
       }
     }
-  }
-  else if ( val.type() == QVariant::StringList )
-  {
-    Q_FOREACH ( const QString &s, val.toStringList() )
+    else if ( var.canConvert<QgsProperty>() )
+      resultStringList << var.value< QgsProperty >().valueAsString( context.expressionContext(), definition->defaultValue().toString() );
+    else if ( QgsMapLayer *layer = qobject_cast< QgsMapLayer * >( qvariant_cast<QObject *>( var ) ) )
     {
-      resultStringList << s;
+      layers << layer;
     }
-  }
-  else
-    resultStringList << val.toString();
+    else
+    {
+      resultStringList << var.toString();
+    }
+  };
+
+  processVariant( val );
 
   if ( layers.isEmpty() && ( resultStringList.isEmpty() || resultStringList.at( 0 ).isEmpty() ) )
   {

tests/src/core/testqgsprocessing.cpp

@@ -2183,7 +2183,8 @@ void TestQgsProcessing::parameterLayerList()
   QFileInfo fi1( raster1 );
   QgsRasterLayer *r1 = new QgsRasterLayer( fi1.filePath(), "R1" );
   QgsVectorLayer *v1 = new QgsVectorLayer( "Polygon?crs=EPSG:3111", "V4", "memory" );
-  p.addMapLayers( QList<QgsMapLayer *>() << v1 << r1 );
+  QgsVectorLayer *v2 = new QgsVectorLayer( "Polygon?crs=EPSG:3111", "V5", "memory" );
+  p.addMapLayers( QList<QgsMapLayer *>() << v1 << v2 << r1 );
   QgsProcessingContext context;
   context.setProject( &p );
 
@@ -2225,6 +2226,14 @@ void TestQgsProcessing::parameterLayerList()
   params.insert( "non_optional",  QVariantList() << QVariant::fromValue( v1 ) << QVariant::fromValue( r1 ) );
   QCOMPARE( QgsProcessingParameters::parameterAsLayerList( def.get(), params, context ), QList< QgsMapLayer *>() << v1 << r1 );
 
+  // mix of list and single layers (happens from models)
+  params.insert( "non_optional",  QVariantList() << QVariant( QVariantList() << QVariant::fromValue( v1 ) << QVariant::fromValue( v2 ) ) << QVariant::fromValue( r1 ) );
+  QCOMPARE( QgsProcessingParameters::parameterAsLayerList( def.get(), params, context ), QList< QgsMapLayer *>() << v1 << v2 << r1 );
+
+  // mix of two lists (happens from models)
+  params.insert( "non_optional",  QVariantList() << QVariant( QVariantList() << QVariant::fromValue( v1 ) << QVariant::fromValue( v2 ) ) << QVariant( QVariantList() << QVariant::fromValue( r1 ) ) );
+  QCOMPARE( QgsProcessingParameters::parameterAsLayerList( def.get(), params, context ), QList< QgsMapLayer *>() << v1 << v2 << r1 );
+
   // mix of existing layers and non project layer string
   params.insert( "non_optional",  QVariantList() << v1->id() << raster2 );
   QList< QgsMapLayer *> layers = QgsProcessingParameters::parameterAsLayerList( def.get(), params, context );