diff --git a/python/gui/editorwidgets/core/qgseditorwidgetwrapper.sip b/python/gui/editorwidgets/core/qgseditorwidgetwrapper.sip
index 2dfdceeee2d..eb6d58ccdd3 100644
--- a/python/gui/editorwidgets/core/qgseditorwidgetwrapper.sip
+++ b/python/gui/editorwidgets/core/qgseditorwidgetwrapper.sip
@@ -88,6 +88,7 @@ class QgsEditorWidgetWrapper : QObject
      */
     void setEnabled( bool enabled );
 
+    virtual bool valid() = 0;
   protected:
     virtual QWidget* createWidget( QWidget* parent ) = 0;
 
diff --git a/python/gui/editorwidgets/core/qgswidgetwrapper.sip b/python/gui/editorwidgets/core/qgswidgetwrapper.sip
index 684475c94a9..27230114618 100644
--- a/python/gui/editorwidgets/core/qgswidgetwrapper.sip
+++ b/python/gui/editorwidgets/core/qgswidgetwrapper.sip
@@ -111,6 +111,17 @@ class QgsWidgetWrapper : QObject
      */
     static QgsWidgetWrapper* fromWidget( QWidget* widget );
 
+    /**
+     * Return true if the widget has been properly initialized.
+     * This acts as hint for the calling party if this wrapper can be used
+     * after initializing it.
+     * If it cannot be used this is a hint tothe caller that he may try to find
+     * another suitable widget type instead.
+     *
+     * @return Validity status of this widget.
+     */
+    virtual bool valid() = 0;
+
   protected:
     /**
      * This method should create a new widget with the provided parent. This will only be called
diff --git a/src/gui/editorwidgets/core/qgseditorwidgetfactory.cpp b/src/gui/editorwidgets/core/qgseditorwidgetfactory.cpp
index dc4741a5b26..29f9dc55afc 100644
--- a/src/gui/editorwidgets/core/qgseditorwidgetfactory.cpp
+++ b/src/gui/editorwidgets/core/qgseditorwidgetfactory.cpp
@@ -30,8 +30,9 @@ QgsEditorWidgetFactory::~QgsEditorWidgetFactory()
 {
 }
 
-/** Override in own factory to get something different than the default (a simple QgsFilterLineEdit)
- *
+/**
+ * By default a simple QgsFilterLineEdit is returned as search widget.
+ * Override in own factory to get something different than the default.
  */
 QgsSearchWidgetWrapper* QgsEditorWidgetFactory::createSearchWidget( QgsVectorLayer* vl, int fieldIdx, QWidget* parent ) const
 {
diff --git a/src/gui/editorwidgets/core/qgseditorwidgetfactory.h b/src/gui/editorwidgets/core/qgseditorwidgetfactory.h
index 056cf4d2747..47f3180602b 100644
--- a/src/gui/editorwidgets/core/qgseditorwidgetfactory.h
+++ b/src/gui/editorwidgets/core/qgseditorwidgetfactory.h
@@ -115,6 +115,15 @@ class GUI_EXPORT QgsEditorWidgetFactory
      */
     inline bool supportsField( QgsVectorLayer* vl, int fieldIdx ) { return isFieldSupported( vl, fieldIdx ); }
 
+    /**
+     * Returns a list of widget types which this editor widget supports.
+     * Each widget type can have a priority value attached, the factory with the highest one
+     * will be used.
+     *
+     * @return A map of widget type names and weight values
+     */
+    virtual QMap<const char*, int> supportedWidgetTypes() { return QMap<const char*, int>(); }
+
     /**
      * Create a pretty String representation of the value.
      *
diff --git a/src/gui/editorwidgets/core/qgseditorwidgetregistry.cpp b/src/gui/editorwidgets/core/qgseditorwidgetregistry.cpp
index f1af4b13943..31b50869bff 100644
--- a/src/gui/editorwidgets/core/qgseditorwidgetregistry.cpp
+++ b/src/gui/editorwidgets/core/qgseditorwidgetregistry.cpp
@@ -95,9 +95,21 @@ QgsEditorWidgetWrapper* QgsEditorWidgetRegistry::create( const QString& widgetId
       // Make sure that there is a widget created at this point
       // so setValue() et al won't crash
       ww->widget();
+
+      // If we tried to set a widget which is not supported by this wrapper
+      if ( !ww->valid() )
+      {
+        delete ww;
+        QString wid = findSuitableWrapper( editor );
+        ww = mWidgetFactories[wid]->create( vl, fieldIdx, editor, parent );
+        ww->setConfig( config );
+        ww->setContext( context );
+      }
+
       return ww;
     }
   }
+
   return 0;
 }
 
@@ -164,6 +176,20 @@ bool QgsEditorWidgetRegistry::registerWidget( const QString& widgetId, QgsEditor
   else
   {
     mWidgetFactories.insert( widgetId, widgetFactory );
+
+    // Use this factory as default where it provides the heighest priority
+    QMap<const char*, int> types = widgetFactory->supportedWidgetTypes();
+    QMap<const char*, int>::ConstIterator it;
+    it = types.constBegin();
+
+    for ( ; it != types.constEnd(); ++it )
+    {
+      if ( it.value() > mFactoriesByType[it.key()].first )
+      {
+        mFactoriesByType[it.key()] = qMakePair( it.value(), widgetFactory );
+      }
+    }
+
     return true;
   }
 }
@@ -316,3 +342,32 @@ void QgsEditorWidgetRegistry::writeSymbology( QDomElement& element, QDomDocument
 
   writeMapLayer( vl, element, doc );
 }
+
+QString QgsEditorWidgetRegistry::findSuitableWrapper( QWidget* editor )
+{
+  QMap<const char*, QPair<int, QgsEditorWidgetFactory*> >::ConstIterator it;
+
+  QString widgetid;
+  int weight = 0;
+
+  it = mFactoriesByType.constBegin();
+  for ( ; it != mFactoriesByType.constEnd(); ++it )
+  {
+    if ( editor->staticMetaObject.className() == it.key() )
+    {
+      // if it's a perfect match: return it directly
+      return it.value().second->name();
+    }
+    else if ( editor->inherits( it.key() ) )
+    {
+      // if it's a subclass, continue evaluating, maybe we find a more-specific or one with more weight
+      if ( it.value().first > weight )
+      {
+        weight = it.value().first;
+        widgetid = it.value().second->name();
+      }
+    }
+  }
+
+  return widgetid;
+}
diff --git a/src/gui/editorwidgets/core/qgseditorwidgetregistry.h b/src/gui/editorwidgets/core/qgseditorwidgetregistry.h
index c5ffcd2cb4f..921d2d4e94e 100644
--- a/src/gui/editorwidgets/core/qgseditorwidgetregistry.h
+++ b/src/gui/editorwidgets/core/qgseditorwidgetregistry.h
@@ -193,7 +193,10 @@ class GUI_EXPORT QgsEditorWidgetRegistry : public QObject
     void writeSymbology( QDomElement& element, QDomDocument& doc, QString& errorMessage );
 
   private:
+    QString findSuitableWrapper( QWidget* editor );
+
     QMap<QString, QgsEditorWidgetFactory*> mWidgetFactories;
+    QMap<const char*, QPair<int, QgsEditorWidgetFactory*> > mFactoriesByType;
 };
 
 #endif // QGSEDITORWIDGETREGISTRY_H
diff --git a/src/gui/editorwidgets/core/qgswidgetwrapper.h b/src/gui/editorwidgets/core/qgswidgetwrapper.h
index 85b71f543ab..8d8b536c6fe 100644
--- a/src/gui/editorwidgets/core/qgswidgetwrapper.h
+++ b/src/gui/editorwidgets/core/qgswidgetwrapper.h
@@ -119,6 +119,17 @@ class GUI_EXPORT QgsWidgetWrapper : public QObject
      */
     static QgsWidgetWrapper* fromWidget( QWidget* widget );
 
+    /**
+     * Return true if the widget has been properly initialized.
+     * This acts as hint for the calling party if this wrapper can be used
+     * after initializing it.
+     * If it cannot be used this is a hint tothe caller that he may try to find
+     * another suitable widget type instead.
+     *
+     * @return Validity status of this widget.
+     */
+    virtual bool valid() = 0;
+
   protected:
     /**
      * This method should create a new widget with the provided parent. This will only be called
diff --git a/src/gui/editorwidgets/qgscheckboxwidgetwrapper.cpp b/src/gui/editorwidgets/qgscheckboxwidgetwrapper.cpp
index 20c3bae9e1d..ec2d312002d 100644
--- a/src/gui/editorwidgets/qgscheckboxwidgetwrapper.cpp
+++ b/src/gui/editorwidgets/qgscheckboxwidgetwrapper.cpp
@@ -53,6 +53,11 @@ void QgsCheckboxWidgetWrapper::initWidget( QWidget* editor )
     connect( mGroupBox, SIGNAL( toggled( bool ) ), this, SLOT( valueChanged( bool ) ) );
 }
 
+bool QgsCheckboxWidgetWrapper::valid()
+{
+  return mCheckBox || mGroupBox;
+}
+
 void QgsCheckboxWidgetWrapper::setValue( const QVariant& value )
 {
   if ( mGroupBox )
diff --git a/src/gui/editorwidgets/qgscheckboxwidgetwrapper.h b/src/gui/editorwidgets/qgscheckboxwidgetwrapper.h
index 0bfd1960137..3f994b9fb7c 100644
--- a/src/gui/editorwidgets/qgscheckboxwidgetwrapper.h
+++ b/src/gui/editorwidgets/qgscheckboxwidgetwrapper.h
@@ -45,6 +45,7 @@ class GUI_EXPORT QgsCheckboxWidgetWrapper : public QgsEditorWidgetWrapper
   protected:
     QWidget* createWidget( QWidget* parent ) override;
     void initWidget( QWidget* editor ) override;
+    bool valid() override;
 
   public slots:
     void setValue( const QVariant& value ) override;
diff --git a/src/gui/editorwidgets/qgsclassificationwidgetwrapper.cpp b/src/gui/editorwidgets/qgsclassificationwidgetwrapper.cpp
index 94cba3e2e16..ccbfeef4bcd 100644
--- a/src/gui/editorwidgets/qgsclassificationwidgetwrapper.cpp
+++ b/src/gui/editorwidgets/qgsclassificationwidgetwrapper.cpp
@@ -59,6 +59,11 @@ void QgsClassificationWidgetWrapper::initWidget( QWidget* editor )
   }
 }
 
+bool QgsClassificationWidgetWrapper::valid()
+{
+  return mComboBox;
+}
+
 void QgsClassificationWidgetWrapper::setValue( const QVariant& value )
 {
   mComboBox->setCurrentIndex( mComboBox->findData( value ) );
diff --git a/src/gui/editorwidgets/qgsclassificationwidgetwrapper.h b/src/gui/editorwidgets/qgsclassificationwidgetwrapper.h
index 3fa6d71ea14..85fa7643486 100644
--- a/src/gui/editorwidgets/qgsclassificationwidgetwrapper.h
+++ b/src/gui/editorwidgets/qgsclassificationwidgetwrapper.h
@@ -33,6 +33,7 @@ class GUI_EXPORT QgsClassificationWidgetWrapper : public QgsEditorWidgetWrapper
   protected:
     QWidget*createWidget( QWidget* parent ) override;
     void initWidget( QWidget* editor ) override;
+    bool valid() override;
 
   public slots:
     void setValue( const QVariant& value ) override;
diff --git a/src/gui/editorwidgets/qgscolorwidgetwrapper.cpp b/src/gui/editorwidgets/qgscolorwidgetwrapper.cpp
index cb8d05cf41a..132dad71b29 100644
--- a/src/gui/editorwidgets/qgscolorwidgetwrapper.cpp
+++ b/src/gui/editorwidgets/qgscolorwidgetwrapper.cpp
@@ -46,6 +46,11 @@ void QgsColorWidgetWrapper::initWidget( QWidget* editor )
   connect( mColorButton, SIGNAL( colorChanged( QColor ) ), this, SLOT( valueChanged() ) );
 }
 
+bool QgsColorWidgetWrapper::valid()
+{
+  return mColorButton;
+}
+
 void QgsColorWidgetWrapper::setValue( const QVariant& value )
 {
   if ( mColorButton )
diff --git a/src/gui/editorwidgets/qgscolorwidgetwrapper.h b/src/gui/editorwidgets/qgscolorwidgetwrapper.h
index 5a7484dd994..5b56169e953 100644
--- a/src/gui/editorwidgets/qgscolorwidgetwrapper.h
+++ b/src/gui/editorwidgets/qgscolorwidgetwrapper.h
@@ -39,6 +39,7 @@ class GUI_EXPORT  QgsColorWidgetWrapper : public QgsEditorWidgetWrapper
   protected:
     QWidget* createWidget( QWidget* parent ) override;
     void initWidget( QWidget* editor ) override;
+    bool valid() override;
 
   public slots:
     void setValue( const QVariant& value ) override;
diff --git a/src/gui/editorwidgets/qgsdatetimeeditwrapper.cpp b/src/gui/editorwidgets/qgsdatetimeeditwrapper.cpp
index bf285a91542..748f5bfd546 100644
--- a/src/gui/editorwidgets/qgsdatetimeeditwrapper.cpp
+++ b/src/gui/editorwidgets/qgsdatetimeeditwrapper.cpp
@@ -90,6 +90,11 @@ void QgsDateTimeEditWrapper::initWidget( QWidget *editor )
   }
 }
 
+bool QgsDateTimeEditWrapper::valid()
+{
+  return mQgsDateTimeEdit || mQDateTimeEdit;
+}
+
 void QgsDateTimeEditWrapper::dateTimeChanged( const QDateTime& dateTime )
 {
   const QString fieldFormat = config( "field_format", QGSDATETIMEEDIT_DATEFORMAT ).toString();
diff --git a/src/gui/editorwidgets/qgsdatetimeeditwrapper.h b/src/gui/editorwidgets/qgsdatetimeeditwrapper.h
index 773eec3d241..0574c3e359e 100644
--- a/src/gui/editorwidgets/qgsdatetimeeditwrapper.h
+++ b/src/gui/editorwidgets/qgsdatetimeeditwrapper.h
@@ -54,6 +54,7 @@ class GUI_EXPORT QgsDateTimeEditWrapper : public QgsEditorWidgetWrapper
     QVariant value() override;
     QWidget *createWidget( QWidget *parent ) override;
     void initWidget( QWidget *editor ) override;
+    bool valid() override;
 
   public slots:
     void setValue( const QVariant &value ) override;
diff --git a/src/gui/editorwidgets/qgsdefaultsearchwidgetwrapper.cpp b/src/gui/editorwidgets/qgsdefaultsearchwidgetwrapper.cpp
index 9f9afa33487..e667492b6d5 100644
--- a/src/gui/editorwidgets/qgsdefaultsearchwidgetwrapper.cpp
+++ b/src/gui/editorwidgets/qgsdefaultsearchwidgetwrapper.cpp
@@ -26,7 +26,7 @@ QgsDefaultSearchWidgetWrapper::QgsDefaultSearchWidgetWrapper( QgsVectorLayer* vl
     , mLineEdit( NULL )
     , mCheckbox( NULL )
     , mContainer( NULL )
-    , mCaseString(QString("LIKE"))
+    , mCaseString( QString( "LIKE" ) )
 {
 }
 
@@ -36,45 +36,45 @@ QString QgsDefaultSearchWidgetWrapper::expression()
   return mExpression;
 }
 
-void QgsDefaultSearchWidgetWrapper::setCaseString(int caseSensitiveCheckState)
+void QgsDefaultSearchWidgetWrapper::setCaseString( int caseSensitiveCheckState )
 {
-    if ( caseSensitiveCheckState == Qt::Checked) 
-    {
-        mCaseString = "LIKE";
-    }
-    else
-    {
-        mCaseString = "ILIKE";
-    }
-    // need to update also the line edit 
-    setExpression(mLineEdit->text());
+  if ( caseSensitiveCheckState == Qt::Checked )
+  {
+    mCaseString = "LIKE";
+  }
+  else
+  {
+    mCaseString = "ILIKE";
+  }
+  // need to update also the line edit
+  setExpression( mLineEdit->text() );
 }
 
-void QgsDefaultSearchWidgetWrapper::setExpression(QString exp)
+void QgsDefaultSearchWidgetWrapper::setExpression( QString exp )
 {
-    QVariant::Type fldType = layer()->pendingFields()[mFieldIdx].type();
-    bool numeric = ( fldType == QVariant::Int || fldType == QVariant::Double || fldType == QVariant::LongLong );
-    
-    QSettings settings;
-    QString nullValue = settings.value( "qgis/nullValue", "NULL" ).toString();
-    QString fieldName = layer()->pendingFields()[mFieldIdx].name();
-    QString str;
-    if ( exp == nullValue )
-    {
-      str = QString( "%1 IS NULL" ).arg( QgsExpression::quotedColumnRef( fieldName ) );
-    }
-    else
-    {
-      str = QString( "%1 %2 '%3'" )
-            .arg( QgsExpression::quotedColumnRef( fieldName ) )
-            .arg( numeric ? "=" : mCaseString )
-            .arg( numeric
-                  ? exp.replace( "'", "''" )
-                  :
-                  "%" + exp.replace( "'", "''" ) + "%" ); // escape quotes
-    }
-    mExpression = str;
-    emit expressionChanged(mExpression);
+  QVariant::Type fldType = layer()->pendingFields()[mFieldIdx].type();
+  bool numeric = ( fldType == QVariant::Int || fldType == QVariant::Double || fldType == QVariant::LongLong );
+
+  QSettings settings;
+  QString nullValue = settings.value( "qgis/nullValue", "NULL" ).toString();
+  QString fieldName = layer()->pendingFields()[mFieldIdx].name();
+  QString str;
+  if ( exp == nullValue )
+  {
+    str = QString( "%1 IS NULL" ).arg( QgsExpression::quotedColumnRef( fieldName ) );
+  }
+  else
+  {
+    str = QString( "%1 %2 '%3'" )
+          .arg( QgsExpression::quotedColumnRef( fieldName ) )
+          .arg( numeric ? "=" : mCaseString )
+          .arg( numeric
+                ? exp.replace( "'", "''" )
+                :
+                "%" + exp.replace( "'", "''" ) + "%" ); // escape quotes
+  }
+  mExpression = str;
+  emit expressionChanged( mExpression );
 }
 
 QWidget* QgsDefaultSearchWidgetWrapper::createWidget( QWidget* parent )
@@ -82,21 +82,26 @@ QWidget* QgsDefaultSearchWidgetWrapper::createWidget( QWidget* parent )
   return new QWidget( parent );
 }
 
-bool QgsDefaultSearchWidgetWrapper::applyDirectly() 
+bool QgsDefaultSearchWidgetWrapper::applyDirectly()
 {
-    return false;
+  return false;
 }
 
 void QgsDefaultSearchWidgetWrapper::initWidget( QWidget* widget )
 {
   mContainer = widget;
-  mContainer->setLayout(new QHBoxLayout() );
+  mContainer->setLayout( new QHBoxLayout() );
   mLineEdit = new QgsFilterLineEdit();
-  mCheckbox = new QCheckBox("Case sensitive");
-  mContainer->layout()->addWidget(mLineEdit);
-  mContainer->layout()->addWidget(mCheckbox);
+  mCheckbox = new QCheckBox( "Case sensitive" );
+  mContainer->layout()->addWidget( mLineEdit );
+  mContainer->layout()->addWidget( mCheckbox );
   connect( mLineEdit, SIGNAL( textChanged( QString ) ), this, SLOT( setExpression( QString ) ) );
-  connect( mCheckbox, SIGNAL( stateChanged( int ) ), this, SLOT( setCaseString(int) ) );
-  mCheckbox->setChecked(Qt::Unchecked);
+  connect( mCheckbox, SIGNAL( stateChanged( int ) ), this, SLOT( setCaseString( int ) ) );
+  mCheckbox->setChecked( Qt::Unchecked );
   mCaseString = "ILIKE";
 }
+
+bool QgsDefaultSearchWidgetWrapper::valid()
+{
+  return true;
+}
diff --git a/src/gui/editorwidgets/qgsdefaultsearchwidgetwrapper.h b/src/gui/editorwidgets/qgsdefaultsearchwidgetwrapper.h
index 0fe1b55f61a..afaba822fdc 100644
--- a/src/gui/editorwidgets/qgsdefaultsearchwidgetwrapper.h
+++ b/src/gui/editorwidgets/qgsdefaultsearchwidgetwrapper.h
@@ -37,14 +37,15 @@ class GUI_EXPORT QgsDefaultSearchWidgetWrapper : public QgsSearchWidgetWrapper
     QString expression() override;
     bool applyDirectly() override;
   protected slots:
-    void setExpression(QString exp) override;
+    void setExpression( QString exp ) override;
 
   private slots:
-    void setCaseString(int);
-    
+    void setCaseString( int );
+
   protected:
     QWidget* createWidget( QWidget* parent ) override;
     void initWidget( QWidget* editor ) override;
+    bool valid() override;
 
   private:
     QgsFilterLineEdit* mLineEdit;
diff --git a/src/gui/editorwidgets/qgsenumerationwidgetwrapper.cpp b/src/gui/editorwidgets/qgsenumerationwidgetwrapper.cpp
index 164689fd240..56f8313dabb 100644
--- a/src/gui/editorwidgets/qgsenumerationwidgetwrapper.cpp
+++ b/src/gui/editorwidgets/qgsenumerationwidgetwrapper.cpp
@@ -57,6 +57,11 @@ void QgsEnumerationWidgetWrapper::initWidget( QWidget* editor )
   }
 }
 
+bool QgsEnumerationWidgetWrapper::valid()
+{
+  return mComboBox;
+}
+
 void QgsEnumerationWidgetWrapper::setValue( const QVariant& value )
 {
   if ( mComboBox )
diff --git a/src/gui/editorwidgets/qgsenumerationwidgetwrapper.h b/src/gui/editorwidgets/qgsenumerationwidgetwrapper.h
index 6ed23bd4b13..c3e416d5304 100644
--- a/src/gui/editorwidgets/qgsenumerationwidgetwrapper.h
+++ b/src/gui/editorwidgets/qgsenumerationwidgetwrapper.h
@@ -33,6 +33,7 @@ class GUI_EXPORT QgsEnumerationWidgetWrapper : public QgsEditorWidgetWrapper
   protected:
     QWidget* createWidget( QWidget* parent ) override;
     void initWidget( QWidget* editor ) override;
+    bool valid() override;
 
   public slots:
     void setValue( const QVariant& value ) override;
diff --git a/src/gui/editorwidgets/qgsfilenamewidgetwrapper.cpp b/src/gui/editorwidgets/qgsfilenamewidgetwrapper.cpp
index 6f1ef30927a..dba79be7bdf 100644
--- a/src/gui/editorwidgets/qgsfilenamewidgetwrapper.cpp
+++ b/src/gui/editorwidgets/qgsfilenamewidgetwrapper.cpp
@@ -47,6 +47,11 @@ QVariant QgsFileNameWidgetWrapper::value()
   return value;
 }
 
+bool QgsFileNameWidgetWrapper::valid()
+{
+  return mLineEdit || mLabel;
+}
+
 QWidget* QgsFileNameWidgetWrapper::createWidget( QWidget* parent )
 {
   QWidget* container = new QWidget( parent );
diff --git a/src/gui/editorwidgets/qgsfilenamewidgetwrapper.h b/src/gui/editorwidgets/qgsfilenamewidgetwrapper.h
index 52740e77c38..ee29516be6e 100644
--- a/src/gui/editorwidgets/qgsfilenamewidgetwrapper.h
+++ b/src/gui/editorwidgets/qgsfilenamewidgetwrapper.h
@@ -40,6 +40,7 @@ class GUI_EXPORT QgsFileNameWidgetWrapper : public QgsEditorWidgetWrapper
     // QgsEditorWidgetWrapper interface
   public:
     QVariant value() override;
+    bool valid() override;
 
   protected:
     QWidget* createWidget( QWidget* parent ) override;
diff --git a/src/gui/editorwidgets/qgshiddenwidgetwrapper.cpp b/src/gui/editorwidgets/qgshiddenwidgetwrapper.cpp
index 5f2b8f2eb46..d69f6e490a6 100644
--- a/src/gui/editorwidgets/qgshiddenwidgetwrapper.cpp
+++ b/src/gui/editorwidgets/qgshiddenwidgetwrapper.cpp
@@ -40,6 +40,11 @@ void QgsHiddenWidgetWrapper::initWidget( QWidget* editor )
   editor->setVisible( false );
 }
 
+bool QgsHiddenWidgetWrapper::valid()
+{
+  return true;
+}
+
 void QgsHiddenWidgetWrapper::setValue( const QVariant& value )
 {
   mValue = value;
diff --git a/src/gui/editorwidgets/qgshiddenwidgetwrapper.h b/src/gui/editorwidgets/qgshiddenwidgetwrapper.h
index 2717b1634a9..765a062d3f5 100644
--- a/src/gui/editorwidgets/qgshiddenwidgetwrapper.h
+++ b/src/gui/editorwidgets/qgshiddenwidgetwrapper.h
@@ -36,6 +36,7 @@ class GUI_EXPORT QgsHiddenWidgetWrapper : public QgsEditorWidgetWrapper
   protected:
     QWidget* createWidget( QWidget* parent ) override;
     void initWidget( QWidget* editor ) override;
+    bool valid() override;
 
   public slots:
     void setValue( const QVariant& value ) override;
diff --git a/src/gui/editorwidgets/qgsphotowidgetwrapper.cpp b/src/gui/editorwidgets/qgsphotowidgetwrapper.cpp
index e5a4e43d5af..2b503277329 100644
--- a/src/gui/editorwidgets/qgsphotowidgetwrapper.cpp
+++ b/src/gui/editorwidgets/qgsphotowidgetwrapper.cpp
@@ -156,6 +156,11 @@ void QgsPhotoWidgetWrapper::initWidget( QWidget* editor )
   }
 }
 
+bool QgsPhotoWidgetWrapper::valid()
+{
+  return mPhotoLabel || mLineEdit || mButton || mWebView;
+}
+
 void QgsPhotoWidgetWrapper::setValue( const QVariant& value )
 {
   if ( mLineEdit )
diff --git a/src/gui/editorwidgets/qgsphotowidgetwrapper.h b/src/gui/editorwidgets/qgsphotowidgetwrapper.h
index 2761b8ab890..d9ee5c1b7e5 100644
--- a/src/gui/editorwidgets/qgsphotowidgetwrapper.h
+++ b/src/gui/editorwidgets/qgsphotowidgetwrapper.h
@@ -48,6 +48,7 @@ class GUI_EXPORT QgsPhotoWidgetWrapper : public QgsEditorWidgetWrapper
   protected:
     QWidget* createWidget( QWidget* parent ) override;
     void initWidget( QWidget* editor ) override;
+    bool valid() override;
 
   public slots:
     void setValue( const QVariant& value ) override;
diff --git a/src/gui/editorwidgets/qgsrangewidgetfactory.cpp b/src/gui/editorwidgets/qgsrangewidgetfactory.cpp
index 123e59f19eb..791b003b3ea 100644
--- a/src/gui/editorwidgets/qgsrangewidgetfactory.cpp
+++ b/src/gui/editorwidgets/qgsrangewidgetfactory.cpp
@@ -84,3 +84,13 @@ bool QgsRangeWidgetFactory::isFieldSupported( QgsVectorLayer* vl, int fieldIdx )
       return false;
   }
 }
+
+QMap<const char*, int> QgsRangeWidgetFactory::supportedWidgetTypes()
+{
+  QMap<const char*, int> map = QMap<const char*, int>();
+  map.insert( QSlider::staticMetaObject.className(), 10 );
+  map.insert( QDial::staticMetaObject.className(), 10 );
+  map.insert( QSpinBox::staticMetaObject.className(), 10 );
+  map.insert( QDoubleSpinBox::staticMetaObject.className(), 10 );
+  return map;
+}
diff --git a/src/gui/editorwidgets/qgsrangewidgetfactory.h b/src/gui/editorwidgets/qgsrangewidgetfactory.h
index ce2ee4dd08e..031c9201e87 100644
--- a/src/gui/editorwidgets/qgsrangewidgetfactory.h
+++ b/src/gui/editorwidgets/qgsrangewidgetfactory.h
@@ -29,6 +29,7 @@ class GUI_EXPORT QgsRangeWidgetFactory : public QgsEditorWidgetFactory
     virtual QgsEditorConfigWidget* configWidget( QgsVectorLayer* vl, int fieldIdx, QWidget* parent ) const override;
     virtual QgsEditorWidgetConfig readConfig( const QDomElement& configElement, QgsVectorLayer* layer, int fieldIdx ) override;
     virtual void writeConfig( const QgsEditorWidgetConfig& config, QDomElement& configElement, QDomDocument& doc, const QgsVectorLayer* layer, int fieldIdx ) override;
+    virtual QMap<const char*, int> supportedWidgetTypes() override;
 
   private:
     virtual bool isFieldSupported( QgsVectorLayer *vl, int fieldIdx ) override;
diff --git a/src/gui/editorwidgets/qgsrangewidgetwrapper.cpp b/src/gui/editorwidgets/qgsrangewidgetwrapper.cpp
index ed099cfd37b..48e1c7360d9 100644
--- a/src/gui/editorwidgets/qgsrangewidgetwrapper.cpp
+++ b/src/gui/editorwidgets/qgsrangewidgetwrapper.cpp
@@ -75,6 +75,10 @@ void QgsRangeWidgetWrapper::initWidget( QWidget* editor )
 
   bool allowNull = config( "AllowNull" ).toBool();
 
+  QVariant min( config( "Min" ) );
+  QVariant max( config( "Max" ) );
+  QVariant step( config( "Step" ) );
+
   if ( mDoubleSpinBox )
   {
     // set the precision if field is integer
@@ -84,8 +88,8 @@ void QgsRangeWidgetWrapper::initWidget( QWidget* editor )
       mDoubleSpinBox->setDecimals( layer()->pendingFields()[fieldIdx()].precision() );
     }
 
-    double min = config( "Min" ).toDouble();
-    double step = config( "Step" ).toDouble();
+    double minval = min.toDouble();
+    double stepval = step.toDouble();
     QgsDoubleSpinBox* qgsWidget = dynamic_cast<QgsDoubleSpinBox*>( mDoubleSpinBox );
     if ( qgsWidget )
       qgsWidget->setShowClearButton( allowNull );
@@ -93,90 +97,107 @@ void QgsRangeWidgetWrapper::initWidget( QWidget* editor )
     {
       if ( precision > 0 )
       {
-        min -= 10 ^ -precision;
+        minval -= 10 ^ -precision;
       }
       else
       {
-        min -= step;
+        minval -= stepval;
       }
-      mDoubleSpinBox->setValue( min );
+      mDoubleSpinBox->setValue( minval );
       mDoubleSpinBox->setSpecialValueText( QSettings().value( "qgis/nullValue", "NULL" ).toString() );
     }
-    mDoubleSpinBox->setMinimum( min );
-    mDoubleSpinBox->setMaximum( config( "Max" ).toDouble() );
-    mDoubleSpinBox->setSingleStep( step );
+    if ( min.isValid() )
+      mDoubleSpinBox->setMinimum( min.toDouble() );
+    if ( max.isValid() )
+      mDoubleSpinBox->setMaximum( max.toDouble() );
+    if ( step.isValid() )
+      mDoubleSpinBox->setSingleStep( step.toDouble() );
     if ( config( "Suffix" ).isValid() )
-    {
       mDoubleSpinBox->setSuffix( config( "Suffix" ).toString() );
-    }
+
     connect( mDoubleSpinBox, SIGNAL( valueChanged( double ) ), this, SLOT( valueChanged( double ) ) );
   }
 
   if ( mIntSpinBox )
   {
-    int min = config( "Min" ).toInt();
-    int step = config( "Step" ).toInt();
+    int minval = min.toInt();
+    int stepval = step.toInt();
     QgsSpinBox* qgsWidget = dynamic_cast<QgsSpinBox*>( mIntSpinBox );
     if ( qgsWidget )
       qgsWidget->setShowClearButton( allowNull );
     if ( allowNull )
     {
-      min -= step;
-      mIntSpinBox->setValue( min );
+      minval -= stepval;
+      mIntSpinBox->setValue( minval );
       mIntSpinBox->setSpecialValueText( QSettings().value( "qgis/nullValue", "NULL" ).toString() );
     }
-    mIntSpinBox->setMinimum( min );
-    mIntSpinBox->setMaximum( config( "Max" ).toInt() );
-    mIntSpinBox->setSingleStep( step );
+    if ( min.isValid() )
+      mIntSpinBox->setMinimum( min.toInt() );
+    if ( max.isValid() )
+      mIntSpinBox->setMaximum( max.toInt() );
+    if ( step.isValid() )
+      mIntSpinBox->setSingleStep( step.toInt() );
     if ( config( "Suffix" ).isValid() )
-    {
       mIntSpinBox->setSuffix( config( "Suffix" ).toString() );
-    }
     connect( mIntSpinBox, SIGNAL( valueChanged( int ) ), this, SLOT( valueChanged( int ) ) );
   }
 
+
   if ( mQgsDial || mQgsSlider )
   {
-    QVariant min( config( "Min" ) );
-    QVariant max( config( "Max" ) );
-    QVariant step( config( "Step" ) );
-
     field().convertCompatible( min );
     field().convertCompatible( max );
     field().convertCompatible( step );
 
     if ( mQgsSlider )
     {
-      mQgsSlider->setMinimum( min );
-      mQgsSlider->setMaximum( max );
-      mQgsSlider->setSingleStep( step );
+      if ( min.isValid() )
+        mQgsSlider->setMinimum( min );
+      if ( max.isValid() )
+        mQgsSlider->setMaximum( max );
+      if ( step.isValid() )
+        mQgsSlider->setSingleStep( step );
     }
 
     if ( mQgsDial )
     {
-      mQgsDial->setMinimum( min );
-      mQgsDial->setMaximum( max );
-      mQgsDial->setSingleStep( step );
+      if ( min.isValid() )
+        mQgsDial->setMinimum( min );
+      if ( max.isValid() )
+        mQgsDial->setMaximum( max );
+      if ( step.isValid() )
+        mQgsDial->setSingleStep( step );
     }
 
     connect( editor, SIGNAL( valueChanged( QVariant ) ), this, SLOT( valueChanged( QVariant ) ) );
   }
   else if ( mDial )
   {
-    mDial->setMinimum( config( "Min" ).toInt() );
-    mDial->setMaximum( config( "Max" ).toInt() );
-    mDial->setSingleStep( config( "Step" ).toInt() );
+    if ( min.isValid() )
+      mDial->setMinimum( min.toInt() );
+    if ( max.isValid() )
+      mDial->setMaximum( max.toInt() );
+    if ( step.isValid() )
+      mDial->setSingleStep( step.toInt() );
     connect( mDial, SIGNAL( valueChanged( int ) ), this, SLOT( valueChanged( int ) ) );
   }
   else if ( mSlider )
   {
-    mSlider->setMinimum( config( "Min" ).toInt() );
-    mSlider->setMaximum( config( "Max" ).toInt() );
-    mSlider->setSingleStep( config( "Step" ).toInt() );
+    if ( min.isValid() )
+      mSlider->setMinimum( min.toInt() );
+    if ( max.isValid() )
+      mSlider->setMaximum( max.toInt() );
+    if ( step.isValid() )
+      mSlider->setSingleStep( step.toInt() );
     connect( mSlider, SIGNAL( valueChanged( int ) ), this, SLOT( valueChanged( int ) ) );
   }
 }
 
+bool QgsRangeWidgetWrapper::valid()
+{
+  return mSlider || mDial || mQgsDial || mQgsSlider || mIntSpinBox || mDoubleSpinBox;
+}
+
 void QgsRangeWidgetWrapper::valueChanged( QVariant v )
 {
   if ( v.type() == QVariant::Int )
diff --git a/src/gui/editorwidgets/qgsrangewidgetwrapper.h b/src/gui/editorwidgets/qgsrangewidgetwrapper.h
index d96d27e6418..51e59e48f77 100644
--- a/src/gui/editorwidgets/qgsrangewidgetwrapper.h
+++ b/src/gui/editorwidgets/qgsrangewidgetwrapper.h
@@ -50,6 +50,7 @@ class GUI_EXPORT QgsRangeWidgetWrapper : public QgsEditorWidgetWrapper
   protected:
     virtual QWidget* createWidget( QWidget* parent ) override;
     virtual void initWidget( QWidget* editor ) override;
+    bool valid() override;
 
   public slots:
     virtual void setValue( const QVariant& value ) override;
diff --git a/src/gui/editorwidgets/qgsrelationreferencewidgetwrapper.cpp b/src/gui/editorwidgets/qgsrelationreferencewidgetwrapper.cpp
index c4d76a8dfc8..87dbdac0fa4 100644
--- a/src/gui/editorwidgets/qgsrelationreferencewidgetwrapper.cpp
+++ b/src/gui/editorwidgets/qgsrelationreferencewidgetwrapper.cpp
@@ -99,6 +99,11 @@ QVariant QgsRelationReferenceWidgetWrapper::value()
   }
 }
 
+bool QgsRelationReferenceWidgetWrapper::valid()
+{
+  return mWidget;
+}
+
 void QgsRelationReferenceWidgetWrapper::setValue( const QVariant& val )
 {
   if ( !mWidget || val == value() )
diff --git a/src/gui/editorwidgets/qgsrelationreferencewidgetwrapper.h b/src/gui/editorwidgets/qgsrelationreferencewidgetwrapper.h
index 0516e340a21..df10592f2e7 100644
--- a/src/gui/editorwidgets/qgsrelationreferencewidgetwrapper.h
+++ b/src/gui/editorwidgets/qgsrelationreferencewidgetwrapper.h
@@ -49,6 +49,7 @@ class GUI_EXPORT QgsRelationReferenceWidgetWrapper : public QgsEditorWidgetWrapp
     virtual QWidget* createWidget( QWidget* parent ) override;
     virtual void initWidget( QWidget* editor ) override;
     virtual QVariant value() override;
+    bool valid() override;
 
   public slots:
     virtual void setValue( const QVariant& value ) override;
diff --git a/src/gui/editorwidgets/qgsrelationwidgetwrapper.cpp b/src/gui/editorwidgets/qgsrelationwidgetwrapper.cpp
index 4086639a780..1096dcec63e 100644
--- a/src/gui/editorwidgets/qgsrelationwidgetwrapper.cpp
+++ b/src/gui/editorwidgets/qgsrelationwidgetwrapper.cpp
@@ -73,3 +73,8 @@ void QgsRelationWidgetWrapper::initWidget( QWidget* editor )
 
   mWidget = w;
 }
+
+bool QgsRelationWidgetWrapper::valid()
+{
+  return mWidget;
+}
diff --git a/src/gui/editorwidgets/qgsrelationwidgetwrapper.h b/src/gui/editorwidgets/qgsrelationwidgetwrapper.h
index 1f18882608e..7ad8298312c 100644
--- a/src/gui/editorwidgets/qgsrelationwidgetwrapper.h
+++ b/src/gui/editorwidgets/qgsrelationwidgetwrapper.h
@@ -30,6 +30,7 @@ class GUI_EXPORT QgsRelationWidgetWrapper : public QgsWidgetWrapper
   protected:
     QWidget* createWidget( QWidget* parent ) override;
     void initWidget( QWidget* editor ) override;
+    bool valid() override;
 
   public slots:
     void setFeature( const QgsFeature& feature ) override;
diff --git a/src/gui/editorwidgets/qgstexteditwrapper.cpp b/src/gui/editorwidgets/qgstexteditwrapper.cpp
index 340ddfc46a9..fbc4370a355 100644
--- a/src/gui/editorwidgets/qgstexteditwrapper.cpp
+++ b/src/gui/editorwidgets/qgstexteditwrapper.cpp
@@ -130,6 +130,11 @@ void QgsTextEditWrapper::initWidget( QWidget* editor )
   }
 }
 
+bool QgsTextEditWrapper::valid()
+{
+  return mLineEdit || mTextEdit || mPlainTextEdit;
+}
+
 void QgsTextEditWrapper::setValue( const QVariant& val )
 {
   QString v;
diff --git a/src/gui/editorwidgets/qgstexteditwrapper.h b/src/gui/editorwidgets/qgstexteditwrapper.h
index 6264c1122ff..04c53dd98e5 100644
--- a/src/gui/editorwidgets/qgstexteditwrapper.h
+++ b/src/gui/editorwidgets/qgstexteditwrapper.h
@@ -46,6 +46,7 @@ class GUI_EXPORT QgsTextEditWrapper : public QgsEditorWidgetWrapper
   protected:
     QWidget*createWidget( QWidget* parent ) override;
     void initWidget( QWidget* editor ) override;
+    bool valid() override;
 
   public slots:
     void setValue( const QVariant& value ) override;
diff --git a/src/gui/editorwidgets/qgsuniquevaluewidgetwrapper.cpp b/src/gui/editorwidgets/qgsuniquevaluewidgetwrapper.cpp
index 3347ebe3af3..a13eb910842 100644
--- a/src/gui/editorwidgets/qgsuniquevaluewidgetwrapper.cpp
+++ b/src/gui/editorwidgets/qgsuniquevaluewidgetwrapper.cpp
@@ -100,6 +100,11 @@ void QgsUniqueValuesWidgetWrapper::initWidget( QWidget* editor )
   }
 }
 
+bool QgsUniqueValuesWidgetWrapper::valid()
+{
+  return mComboBox || mLineEdit;
+}
+
 void QgsUniqueValuesWidgetWrapper::setValue( const QVariant& value )
 {
   if ( mComboBox )
diff --git a/src/gui/editorwidgets/qgsuniquevaluewidgetwrapper.h b/src/gui/editorwidgets/qgsuniquevaluewidgetwrapper.h
index f59b42b5f71..8dfd3b23c4c 100644
--- a/src/gui/editorwidgets/qgsuniquevaluewidgetwrapper.h
+++ b/src/gui/editorwidgets/qgsuniquevaluewidgetwrapper.h
@@ -44,6 +44,7 @@ class GUI_EXPORT QgsUniqueValuesWidgetWrapper : public QgsEditorWidgetWrapper
   protected:
     QWidget* createWidget( QWidget* parent ) override;
     void initWidget( QWidget* editor ) override;
+    bool valid() override;
 
   public slots:
     void setValue( const QVariant& value ) override;
diff --git a/src/gui/editorwidgets/qgsuuidwidgetwrapper.cpp b/src/gui/editorwidgets/qgsuuidwidgetwrapper.cpp
index cda5fe52a1e..de7989ef124 100644
--- a/src/gui/editorwidgets/qgsuuidwidgetwrapper.cpp
+++ b/src/gui/editorwidgets/qgsuuidwidgetwrapper.cpp
@@ -49,6 +49,11 @@ void QgsUuidWidgetWrapper::initWidget( QWidget* editor )
     mLineEdit->setEnabled( false );
 }
 
+bool QgsUuidWidgetWrapper::valid()
+{
+  return mLineEdit || mLabel;
+}
+
 void QgsUuidWidgetWrapper::setValue( const QVariant& value )
 {
   if ( value.isNull() )
diff --git a/src/gui/editorwidgets/qgsuuidwidgetwrapper.h b/src/gui/editorwidgets/qgsuuidwidgetwrapper.h
index 4029b9d27e4..6dc437d285e 100644
--- a/src/gui/editorwidgets/qgsuuidwidgetwrapper.h
+++ b/src/gui/editorwidgets/qgsuuidwidgetwrapper.h
@@ -41,6 +41,7 @@ class GUI_EXPORT QgsUuidWidgetWrapper : public QgsEditorWidgetWrapper
   protected:
     QWidget* createWidget( QWidget* parent ) override;
     void initWidget( QWidget* editor ) override;
+    bool valid() override;
 
   public slots:
     void setValue( const QVariant& value ) override;
diff --git a/src/gui/editorwidgets/qgsvaluemapwidgetfactory.cpp b/src/gui/editorwidgets/qgsvaluemapwidgetfactory.cpp
index 1fdb692cbd7..204b07b650f 100644
--- a/src/gui/editorwidgets/qgsvaluemapwidgetfactory.cpp
+++ b/src/gui/editorwidgets/qgsvaluemapwidgetfactory.cpp
@@ -88,3 +88,10 @@ QString QgsValueMapWidgetFactory::representValue( QgsVectorLayer* vl, int fieldI
 
   return config.key( value, QVariant( QString( "(%1)" ).arg( value.toString() ) ).toString() );
 }
+
+QMap<const char*, int> QgsValueMapWidgetFactory::supportedWidgetTypes()
+{
+  QMap<const char*, int> map = QMap<const char*, int>();
+  map.insert( QComboBox::staticMetaObject.className(), 10 );
+  return map;
+}
diff --git a/src/gui/editorwidgets/qgsvaluemapwidgetfactory.h b/src/gui/editorwidgets/qgsvaluemapwidgetfactory.h
index 2a28a7afb88..ec738b909ff 100644
--- a/src/gui/editorwidgets/qgsvaluemapwidgetfactory.h
+++ b/src/gui/editorwidgets/qgsvaluemapwidgetfactory.h
@@ -31,6 +31,7 @@ class GUI_EXPORT QgsValueMapWidgetFactory : public QgsEditorWidgetFactory
     QgsEditorWidgetConfig readConfig( const QDomElement& configElement, QgsVectorLayer* layer, int fieldIdx ) override;
     void writeConfig( const QgsEditorWidgetConfig& config, QDomElement& configElement, QDomDocument& doc, const QgsVectorLayer* layer, int fieldIdx ) override;
     QString representValue( QgsVectorLayer* vl, int fieldIdx, const QgsEditorWidgetConfig& config, const QVariant& cache, const QVariant& value ) const override;
+    virtual QMap<const char*, int> supportedWidgetTypes() override;
 };
 
 #endif // QGSVALUEMAPWIDGETFACTORY_H
diff --git a/src/gui/editorwidgets/qgsvaluemapwidgetwrapper.cpp b/src/gui/editorwidgets/qgsvaluemapwidgetwrapper.cpp
index b423ef5b9db..36335676eef 100644
--- a/src/gui/editorwidgets/qgsvaluemapwidgetwrapper.cpp
+++ b/src/gui/editorwidgets/qgsvaluemapwidgetwrapper.cpp
@@ -55,6 +55,11 @@ void QgsValueMapWidgetWrapper::initWidget( QWidget* editor )
   }
 }
 
+bool QgsValueMapWidgetWrapper::valid()
+{
+  return mComboBox;
+}
+
 void QgsValueMapWidgetWrapper::setValue( const QVariant& value )
 {
   if ( mComboBox )
diff --git a/src/gui/editorwidgets/qgsvaluemapwidgetwrapper.h b/src/gui/editorwidgets/qgsvaluemapwidgetwrapper.h
index 696782c04a2..c5baf5f8691 100644
--- a/src/gui/editorwidgets/qgsvaluemapwidgetwrapper.h
+++ b/src/gui/editorwidgets/qgsvaluemapwidgetwrapper.h
@@ -46,6 +46,7 @@ class GUI_EXPORT QgsValueMapWidgetWrapper : public QgsEditorWidgetWrapper
   protected:
     QWidget* createWidget( QWidget* parent ) override;
     void initWidget( QWidget* editor ) override;
+    bool valid() override;
 
   public slots:
     void setValue( const QVariant& value ) override;
diff --git a/src/gui/editorwidgets/qgsvaluerelationwidgetwrapper.cpp b/src/gui/editorwidgets/qgsvaluerelationwidgetwrapper.cpp
index ce190ace3f5..82aac0fd44e 100644
--- a/src/gui/editorwidgets/qgsvaluerelationwidgetwrapper.cpp
+++ b/src/gui/editorwidgets/qgsvaluerelationwidgetwrapper.cpp
@@ -25,7 +25,7 @@
 #include <QCompleter>
 
 bool QgsValueRelationWidgetWrapper::orderByKeyLessThan( const QgsValueRelationWidgetWrapper::ValueRelationItem& p1
-                         , const QgsValueRelationWidgetWrapper::ValueRelationItem& p2 )
+    , const QgsValueRelationWidgetWrapper::ValueRelationItem& p2 )
 {
   switch ( p1.first.type() )
   {
@@ -44,7 +44,7 @@ bool QgsValueRelationWidgetWrapper::orderByKeyLessThan( const QgsValueRelationWi
 }
 
 bool QgsValueRelationWidgetWrapper::orderByValueLessThan( const QgsValueRelationWidgetWrapper::ValueRelationItem& p1
-                           , const QgsValueRelationWidgetWrapper::ValueRelationItem& p2 )
+    , const QgsValueRelationWidgetWrapper::ValueRelationItem& p2 )
 {
   return p1.second < p2.second;
 }
@@ -164,6 +164,11 @@ void QgsValueRelationWidgetWrapper::initWidget( QWidget* editor )
   }
 }
 
+bool QgsValueRelationWidgetWrapper::valid()
+{
+  return mListWidget || mLineEdit || mComboBox;
+}
+
 void QgsValueRelationWidgetWrapper::setValue( const QVariant& value )
 {
   if ( mListWidget )
diff --git a/src/gui/editorwidgets/qgsvaluerelationwidgetwrapper.h b/src/gui/editorwidgets/qgsvaluerelationwidgetwrapper.h
index 6623605c87c..d75e283b829 100644
--- a/src/gui/editorwidgets/qgsvaluerelationwidgetwrapper.h
+++ b/src/gui/editorwidgets/qgsvaluerelationwidgetwrapper.h
@@ -55,9 +55,9 @@ class GUI_EXPORT QgsValueRelationWidgetWrapper : public QgsEditorWidgetWrapper
   public:
     explicit QgsValueRelationWidgetWrapper( QgsVectorLayer* vl, int fieldIdx, QWidget* editor = 0, QWidget* parent = 0 );
     static bool orderByKeyLessThan( const QgsValueRelationWidgetWrapper::ValueRelationItem& p1 ,
-            const QgsValueRelationWidgetWrapper::ValueRelationItem& p2 );
+                                    const QgsValueRelationWidgetWrapper::ValueRelationItem& p2 );
     static bool orderByValueLessThan( const QgsValueRelationWidgetWrapper::ValueRelationItem& p1 ,
-            const QgsValueRelationWidgetWrapper::ValueRelationItem& p2 );
+                                      const QgsValueRelationWidgetWrapper::ValueRelationItem& p2 );
 
 
 
@@ -70,6 +70,7 @@ class GUI_EXPORT QgsValueRelationWidgetWrapper : public QgsEditorWidgetWrapper
   protected:
     QWidget* createWidget( QWidget* parent ) override;
     void initWidget( QWidget* editor ) override;
+    bool valid() override;
 
   public slots:
     void setValue( const QVariant& value ) override;
diff --git a/src/gui/editorwidgets/qgswebviewwidgetwrapper.cpp b/src/gui/editorwidgets/qgswebviewwidgetwrapper.cpp
index 2de9109a028..1f2b371310e 100644
--- a/src/gui/editorwidgets/qgswebviewwidgetwrapper.cpp
+++ b/src/gui/editorwidgets/qgswebviewwidgetwrapper.cpp
@@ -121,6 +121,11 @@ void QgsWebViewWidgetWrapper::initWidget( QWidget* editor )
   }
 }
 
+bool QgsWebViewWidgetWrapper::valid()
+{
+  return mWebView || mButton || mLineEdit;
+}
+
 void QgsWebViewWidgetWrapper::setValue( const QVariant& value )
 {
   if ( mLineEdit )
diff --git a/src/gui/editorwidgets/qgswebviewwidgetwrapper.h b/src/gui/editorwidgets/qgswebviewwidgetwrapper.h
index 227a498ef0d..9e10d40e01f 100644
--- a/src/gui/editorwidgets/qgswebviewwidgetwrapper.h
+++ b/src/gui/editorwidgets/qgswebviewwidgetwrapper.h
@@ -41,6 +41,7 @@ class GUI_EXPORT QgsWebViewWidgetWrapper : public QgsEditorWidgetWrapper
   protected:
     QWidget* createWidget( QWidget* parent ) override;
     void initWidget( QWidget* editor ) override;
+    bool valid() override;
 
   public slots:
     void setValue( const QVariant& value ) override;