Fix some missing expression context variables in processing expression based widgets

(cherry picked from commit 60a1d63)

Author: nyalldawson

python/plugins/processing/gui/BatchPanel.py

@@ -35,7 +35,8 @@
 from qgis.core import (Qgis,
                        QgsApplication,
                        QgsSettings,
-                       QgsProcessingParameterDefinition)
+                       QgsProcessingParameterDefinition,
+                       QgsProcessingModelAlgorithm)
 from qgis.gui import (QgsProcessingParameterWidgetContext,
                       QgsProcessingContextGenerator)
 from qgis.utils import iface
@@ -273,6 +274,9 @@ def setCellWrapper(self, row, column, wrapper, context):
             widget_context = QgsProcessingParameterWidgetContext()
             if iface is not None:
                 widget_context.setMapCanvas(iface.mapCanvas())
+            if isinstance(self.alg, QgsProcessingModelAlgorithm):
+                widget_context.setModel(self.alg)
+
             wrapper.setWidgetContext(widget_context)
             widget = wrapper.createWrappedWidget(context)
             wrapper.registerProcessingContextGenerator(self.context_generator)

python/plugins/processing/gui/ParametersPanel.py

@@ -41,7 +41,8 @@
                        QgsProcessingParameterRasterDestination,
                        QgsProcessingParameterFeatureSink,
                        QgsProcessingParameterVectorDestination,
-                       QgsProject)
+                       QgsProject,
+                       QgsProcessingModelAlgorithm)
 from qgis.gui import (QgsProcessingContextGenerator,
                       QgsProcessingParameterWidgetContext)
 from qgis.utils import iface
@@ -128,6 +129,8 @@ def initWidgets(self):
         widget_context = QgsProcessingParameterWidgetContext()
         if iface is not None:
             widget_context.setMapCanvas(iface.mapCanvas())
+        if isinstance(self.alg, QgsProcessingModelAlgorithm):
+            widget_context.setModel(self.alg)
 
         # Create widgets and put them in layouts
         for param in self.alg.parameterDefinitions():

src/gui/processing/qgsprocessingwidgetwrapper.cpp

@@ -243,7 +243,7 @@ QgsExpressionContext QgsAbstractProcessingParameterWidgetWrapper::createExpressi
     if ( mWidgetContext.model()->childAlgorithms().contains( mWidgetContext.modelChildAlgorithmId() ) )
       alg = mWidgetContext.model()->childAlgorithm( mWidgetContext.modelChildAlgorithmId() ).algorithm();
 
-    QgsExpressionContextScope *algorithmScope = QgsExpressionContextUtils::processingAlgorithmScope( alg, QVariantMap(), *context );
+    QgsExpressionContextScope *algorithmScope = QgsExpressionContextUtils::processingAlgorithmScope( alg ? alg : mParameterDefinition->algorithm(), QVariantMap(), *context );
     c << algorithmScope;
     QgsExpressionContextScope *childScope = mWidgetContext.model()->createExpressionContextScopeForChildAlgorithm( mWidgetContext.modelChildAlgorithmId(), *context, QVariantMap(), QVariantMap() );
     c << childScope;
@@ -255,6 +255,11 @@ QgsExpressionContext QgsAbstractProcessingParameterWidgetWrapper::createExpressi
     c.setHighlightedVariables( highlightedVariables );
     c.setHighlightedFunctions( highlightedFunctions );
   }
+  else
+  {
+    if ( mParameterDefinition->algorithm() )
+      c << QgsExpressionContextUtils::processingAlgorithmScope( mParameterDefinition->algorithm(), QVariantMap(), *context );
+  }
 
   if ( linkedVectorLayer() )
     c << QgsExpressionContextUtils::layerScope( linkedVectorLayer() );