Improved search for the relation reference widget

src/gui/editorwidgets/qgsrelationreferencewidget.cpp

@@ -19,6 +19,7 @@
 #include <QDialog>
 #include <QHBoxLayout>
 #include <QTimer>
+#include <QCompleter>
 
 #include "qgsattributeform.h"
 #include "qgsattributetablefiltermodel.h"
@@ -543,6 +544,14 @@ void QgsRelationReferenceWidget::init()
 
     mComboBox->setModel( mFeatureListModel );
 
+    delete mComboBox->completer();
+    QCompleter* completer = new QCompleter( mComboBox->model(), mComboBox );
+    completer->setModel( mComboBox->model() );
+    completer->setFilterMode( Qt::MatchContains );
+    completer->setCaseSensitivity( Qt::CaseInsensitive );
+    mComboBox->setCompleter( completer );
+
+
     QVariant nullValue = QSettings().value( QStringLiteral( "qgis/nullValue" ), "NULL" );
 
     if ( mChainFilters && mFeature.isValid() )