fix(AttributeForm): Update same field widgets before firing signals

If not, saveEdits would be called when we fire widgetValueChanged
signal and widgets containing non updated old values could potentially
overwrite new ones, leading to discard user modifications.

src/gui/qgsattributeform.cpp

@@ -1036,6 +1036,19 @@ void QgsAttributeForm::onAttributeChanged( const QVariant &value, const QVariant
 
   mCurrentFormFeature.setAttribute( eww->field().name(), value );
 
+  // Update other widgets pointing to the same field, required to happen now to insure
+  // currentFormValuesFeature() gets the right value when processing constraints
+  const QList<QgsAttributeFormEditorWidget *> formEditorWidgets = mFormEditorWidgets.values( eww->fieldIdx() );
+  for ( QgsAttributeFormEditorWidget *formEditorWidget : formEditorWidgets )
+  {
+    if ( formEditorWidget->editorWidget() == eww )
+      continue;
+
+    // formEditorWidget and eww points to the same field, so block signals
+    // as there is no need to handle valueChanged again for each duplicate
+    whileBlocking( formEditorWidget->editorWidget() )->setValue( value );
+  }
+
   switch ( mMode )
   {
     case QgsAttributeEditorContext::SingleEditMode:
@@ -1091,19 +1104,6 @@ void QgsAttributeForm::onAttributeChanged( const QVariant &value, const QVariant
       break;
   }
 
-  // Update other widgets pointing to the same field, required to happen now to insure
-  // currentFormValuesFeature() gets the right value when processing constraints
-  const QList<QgsAttributeFormEditorWidget *> formEditorWidgets = mFormEditorWidgets.values( eww->fieldIdx() );
-  for ( QgsAttributeFormEditorWidget *formEditorWidget : formEditorWidgets )
-  {
-    if ( formEditorWidget->editorWidget() == eww )
-      continue;
-
-    // formEditorWidget and eww points to the same field, so block signals
-    // as there is no need to handle valueChanged again for each duplicate
-    whileBlocking( formEditorWidget->editorWidget() )->setValue( value );
-  }
-
   updateConstraints( eww );
 
   // Update dependent fields (only if form is not initializing)

tests/src/gui/testqgsdualview.cpp

@@ -21,6 +21,9 @@
 #include <attributetable/qgsdualview.h>
 #include <editform/qgsattributeeditorhtmlelement.h>
 #include "qgsattributeform.h"
+#include "qgsattributeeditorcontainer.h"
+#include "qgsattributeeditorfield.h"
+#include "qgsattributeformeditorwidget.h"
 #include <qgsapplication.h>
 #include "qgsfeatureiterator.h"
 #include <qgsvectorlayer.h>
@@ -58,6 +61,8 @@ class TestQgsDualView : public QObject
     void testAttributeFormSharedValueScanning();
     void testNoGeom();
 
+    void testDuplicateField();
+
 #ifdef WITH_QTWEBKIT
     void testHtmlWidget_data();
     void testHtmlWidget();
@@ -404,5 +409,46 @@ void TestQgsDualView::testHtmlWidget()
 }
 #endif
 
+void TestQgsDualView::testDuplicateField()
+{
+  // test updating same field appearing in different widget
+
+  // make a temporary vector layer
+  const QString def = QStringLiteral( "Point?field=col0:integer" );
+  QgsVectorLayer *layer = new QgsVectorLayer( def, QStringLiteral( "test" ), QStringLiteral( "memory" ) );
+  layer->setEditorWidgetSetup( 0, QgsEditorWidgetSetup( QStringLiteral( "Range" ), QVariantMap() ) );
+
+  // add same field twice so they get synced
+  QgsEditFormConfig editFormConfig = layer->editFormConfig();
+  editFormConfig.clearTabs();
+  editFormConfig.invisibleRootContainer()->addChildElement( new QgsAttributeEditorField( "col0", 0, editFormConfig.invisibleRootContainer() ) );
+  editFormConfig.invisibleRootContainer()->addChildElement( new QgsAttributeEditorField( "col0", 0, editFormConfig.invisibleRootContainer() ) );
+  editFormConfig.setLayout( Qgis::AttributeFormLayout::DragAndDrop );
+  layer->setEditFormConfig( editFormConfig );
+
+  // add a feature to the vector layer
+  QgsFeature ft( layer->dataProvider()->fields(), 1 );
+  ft.setAttribute( QStringLiteral( "col0" ), 1 );
+  layer->dataProvider()->addFeature( ft );
+
+  QgsDualView dualView;
+  dualView.init( layer, mCanvas );
+
+  layer->startEditing();
+
+  const QList<QgsAttributeFormEditorWidget *> formEditorWidgets = dualView.mAttributeForm->mFormEditorWidgets.values( 0 );
+
+  formEditorWidgets[0]->editorWidget()->setValues( 20, QVariantList() );
+  ft = layer->getFeature( ft.id() );
+  QCOMPARE( ft.attribute( QStringLiteral( "col0" ) ).toInt(), 20 );
+
+  formEditorWidgets[1]->editorWidget()->setValues( 21, QVariantList() );
+  ft = layer->getFeature( ft.id() );
+  QCOMPARE( ft.attribute( QStringLiteral( "col0" ) ).toInt(), 21 );
+
+  layer->rollBack();
+}
+
+
 QGSTEST_MAIN( TestQgsDualView )
 #include "testqgsdualview.moc"