Setup framework for receiving model child results after running through model designer

python/gui/auto_generated/processing/models/qgsmodeldesignerdialog.sip.in

@@ -95,6 +95,11 @@ Checks if the model can current be saved, and returns ``True`` if it can.
 Checks if there are unsaved changes in the model, and if so, prompts the user to save them.
 
 Returns ``False`` if the cancel option was selected
+%End
+
+    void setLastRunChildAlgorithmResults( const QVariantMap &results );
+%Docstring
+Sets the results of child algorithms for the last run of the model through the designer window.
 %End
 
 };

python/gui/auto_generated/processing/qgsprocessingalgorithmdialogbase.sip.in

@@ -299,6 +299,15 @@ by the dialog. Ownership of ``task`` is transferred to the dialog.
 Formats an input ``string`` for display in the log tab.
 
 .. versionadded:: 3.0.1
+%End
+
+  signals:
+
+    void algorithmFinished( bool successful, const QVariantMap &result );
+%Docstring
+Emitted whenever an algorithm has finished executing in the dialog.
+
+.. versionadded:: 3.14
 %End
 
   protected slots:

python/plugins/processing/gui/AlgorithmDialog.py

@@ -342,6 +342,7 @@ class AlgorithmDialog(QgsProcessingAlgorithmDialogBase):
         self.setExecuted(True)
         self.setResults(result)
         self.setInfo(self.tr('Algorithm \'{0}\' finished').format(self.algorithm().displayName()), escapeHtml=False)
+        self.algorithmFinished.emit(successful, result)
 
         if not in_place and not keepOpen:
             self.close()

python/plugins/processing/modeler/ModelerDialog.py

@@ -120,8 +120,12 @@ class ModelerDialog(QgsModelDesignerDialog):
                 duration=5)
             return
 
+        def on_finished(successful, results):
+            self.setLastRunChildAlgorithmResults(dlg.results()['CHILD_RESULTS'])
+
         dlg = AlgorithmDialog(self.model().create(), parent=self)
         dlg.setParameters(self.model().designerParameterValues())
+        dlg.algorithmFinished.connect(on_finished)
         dlg.exec_()
 
         if dlg.wasExecuted():

src/core/processing/models/qgsprocessingmodelalgorithm.cpp

@@ -402,6 +402,7 @@ QVariantMap QgsProcessingModelAlgorithm::processAlgorithm( const QVariantMap &pa
     feedback->pushDebugInfo( QObject::tr( "Model processed OK. Executed %1 algorithms total in %2 s." ).arg( executed.count() ).arg( totalTime.elapsed() / 1000.0 ) );
 
   mResults = finalResults;
+  mResults.insert( QStringLiteral( "CHILD_RESULTS" ), childResults );
   return mResults;
 }
 

src/gui/processing/models/qgsmodeldesignerdialog.cpp

@@ -437,6 +437,11 @@ bool QgsModelDesignerDialog::checkForUnsavedChanges()
   }
 }
 
+void QgsModelDesignerDialog::setLastRunChildAlgorithmResults( const QVariantMap &results )
+{
+  mChildResults = results;
+}
+
 void QgsModelDesignerDialog::zoomIn()
 {
   mView->setTransformationAnchor( QGraphicsView::NoAnchor );

src/gui/processing/models/qgsmodeldesignerdialog.h

@@ -120,6 +120,11 @@ class GUI_EXPORT QgsModelDesignerDialog : public QMainWindow, public Ui::QgsMode
      */
     bool checkForUnsavedChanges();
 
+    /**
+     * Sets the results of child algorithms for the last run of the model through the designer window.
+     */
+    void setLastRunChildAlgorithmResults( const QVariantMap &results );
+
   private slots:
     void zoomIn();
     void zoomOut();
@@ -164,6 +169,8 @@ class GUI_EXPORT QgsModelDesignerDialog : public QMainWindow, public Ui::QgsMode
 
     int mBlockRepaints = 0;
 
+    QVariantMap mChildResults;
+
     bool isDirty() const;
 
     void fillInputsTree();

src/gui/processing/qgsprocessingalgorithmdialogbase.h

@@ -343,6 +343,15 @@ class GUI_EXPORT QgsProcessingAlgorithmDialogBase : public QDialog, private Ui::
      */
     static QString formatStringForLog( const QString &string );
 
+  signals:
+
+    /**
+     * Emitted whenever an algorithm has finished executing in the dialog.
+     *
+     * \since QGIS 3.14
+     */
+    void algorithmFinished( bool successful, const QVariantMap &result );
+
   protected slots:
 
     /**