Allow using NULL values

python/core/qgsfeaturefiltermodel.sip

@@ -141,6 +141,17 @@ class QgsFeatureFilterModel : QAbstractItemModel
  :rtype: bool
 %End
 
+    bool allowNull() const;
+%Docstring
+ Add a NULL entry to the list.
+ :rtype: bool
+%End
+
+    void setAllowNull( bool allowNull );
+%Docstring
+ Add a NULL entry to the list.
+%End
+
   signals:
 
     void sourceLayerChanged();
@@ -211,6 +222,11 @@ class QgsFeatureFilterModel : QAbstractItemModel
  Notification that the model change is finished. Will always be emitted in sync with beginUpdate.
 %End
 
+    void allowNullChanged();
+%Docstring
+ Add a NULL entry to the list.
+%End
+
 };
 
 /************************************************************************

python/gui/qgsfeaturelistcombobox.sip

@@ -92,8 +92,6 @@ class QgsFeatureListComboBox : QComboBox
     bool allowNull() const;
 %Docstring
  Determines if a NULL value should be available in the list.
-
- TODO!
  :rtype: bool
 %End
 

src/core/qgsfeaturefiltermodel.cpp

@@ -165,12 +165,18 @@ void QgsFeatureFilterModel::updateCompleter()
     }
 
     mShouldReloadCurrentFeature = false;
+
+    if ( mFilterValue.isEmpty() )
+      reload();
   }
   else
   {
     // We got strings for a filter selection
     std::sort( entries.begin(), entries.end(), []( const Entry & a, const Entry & b ) { return a.value.localeAwareCompare( b.value ) < 0; } );
 
+    if ( mAllowNull )
+      entries.prepend( Entry( QVariant( QVariant::Int ), tr( "NULL" ) ) );
+
     int newEntriesSize = entries.size();
 
     // Find the index of the extra entry in the new list
@@ -196,6 +202,8 @@ void QgsFeatureFilterModel::updateCompleter()
 
     int firstRow = 0;
 
+    QgsDebugMsg( QStringLiteral( "Entries 1: %1 " ).arg( mEntries.size() ) );
+
     // Move the extra entry to the first position
     if ( mExtraIdentifierValueIndex != -1 )
     {
@@ -213,20 +221,26 @@ void QgsFeatureFilterModel::updateCompleter()
       firstRow = 1;
     }
 
+    QgsDebugMsg( QStringLiteral( "Entries 2: %1 " ).arg( mEntries.size() ) );
+
     // Remove all entries (except for extra entry if existent)
     beginRemoveRows( QModelIndex(), firstRow, mEntries.size() - firstRow );
     mEntries.remove( firstRow, mEntries.size() - firstRow );
     endRemoveRows();
 
+    QgsDebugMsg( QStringLiteral( "Entries 3: %1 " ).arg( mEntries.size() ) );
+
     if ( currentEntryInNewList == -1 )
     {
+      QgsDebugMsg( QStringLiteral( "Current value is NOT in new list" ) );
       beginInsertRows( QModelIndex(), 1, entries.size() + 1 );
       mEntries += entries;
       endInsertRows();
       setExtraIdentifierValueIndex( 0 );
     }
     else
     {
+      QgsDebugMsg( QStringLiteral( "Current value is in new list" ) );
       if ( currentEntryInNewList != 0 )
       {
         beginInsertRows( QModelIndex(), 0, currentEntryInNewList - 1 );
@@ -335,7 +349,7 @@ void QgsFeatureFilterModel::setExtraIdentifierValueUnguarded( const QVariant &ex
   int index = 0;
   for ( const Entry &entry : entries )
   {
-    if ( entry.identifierValue == extraIdentifierValue )
+    if ( entry.identifierValue == extraIdentifierValue && entry.identifierValue.isNull() == extraIdentifierValue.isNull() && entry.identifierValue.isValid() == extraIdentifierValue.isValid() )
     {
       setExtraIdentifierValueIndex( index );
       break;
@@ -348,14 +362,33 @@ void QgsFeatureFilterModel::setExtraIdentifierValueUnguarded( const QVariant &ex
   if ( mExtraIdentifierValueIndex != index )
   {
     beginInsertRows( QModelIndex(), 0, 0 );
-    mEntries.prepend( Entry( extraIdentifierValue, QStringLiteral( "(%1)" ).arg( extraIdentifierValue.toString() ) ) );
+    if ( extraIdentifierValue.isNull() )
+      mEntries.prepend( Entry( QVariant( QVariant::Int ), QStringLiteral( "%1" ).arg( tr( "NULL" ) ) ) );
+    else
+      mEntries.prepend( Entry( extraIdentifierValue, QStringLiteral( "(%1)" ).arg( extraIdentifierValue.toString() ) ) );
     endInsertRows();
     setExtraIdentifierValueIndex( 0 );
 
     reloadCurrentFeature();
   }
 }
 
+bool QgsFeatureFilterModel::allowNull() const
+{
+  return mAllowNull;
+}
+
+void QgsFeatureFilterModel::setAllowNull( bool allowNull )
+{
+  if ( mAllowNull == allowNull )
+    return;
+
+  mAllowNull = allowNull;
+  emit allowNullChanged();
+
+  reload();
+}
+
 bool QgsFeatureFilterModel::extraValueDoesNotExist() const
 {
   return mExtraValueDoesNotExist;
@@ -401,7 +434,7 @@ QVariant QgsFeatureFilterModel::extraIdentifierValue() const
 
 void QgsFeatureFilterModel::setExtraIdentifierValue( const QVariant &extraIdentifierValue )
 {
-  if ( extraIdentifierValue == mExtraIdentifierValue && extraIdentifierValue.isNull() == mExtraIdentifierValue.isNull() )
+  if ( extraIdentifierValue == mExtraIdentifierValue && extraIdentifierValue.isNull() == mExtraIdentifierValue.isNull() && mExtraIdentifierValue.isValid() )
     return;
 
   setExtraIdentifierValueUnguarded( extraIdentifierValue );

src/core/qgsfeaturefiltermodel.h

@@ -37,6 +37,7 @@ class CORE_EXPORT QgsFeatureFilterModel : public QAbstractItemModel
     Q_PROPERTY( QString displayExpression READ displayExpression WRITE setDisplayExpression NOTIFY displayExpressionChanged )
     Q_PROPERTY( QString filterValue READ filterValue WRITE setFilterValue NOTIFY filterValueChanged )
     Q_PROPERTY( QString filterExpression READ filterExpression WRITE setFilterExpression NOTIFY filterExpressionChanged )
+    Q_PROPERTY( bool allowNull READ allowNull WRITE setAllowNull NOTIFY allowNullChanged )
     Q_PROPERTY( bool isLoading READ isLoading NOTIFY isLoadingChanged )
 
     /**
@@ -167,6 +168,16 @@ class CORE_EXPORT QgsFeatureFilterModel : public QAbstractItemModel
      */
     bool extraValueDoesNotExist() const;
 
+    /**
+     * Add a NULL entry to the list.
+     */
+    bool allowNull() const;
+
+    /**
+     * Add a NULL entry to the list.
+     */
+    void setAllowNull( bool allowNull );
+
   signals:
 
     /**
@@ -237,6 +248,11 @@ class CORE_EXPORT QgsFeatureFilterModel : public QAbstractItemModel
      */
     void endUpdate();
 
+    /**
+     * Add a NULL entry to the list.
+     */
+    void allowNullChanged();
+
   private slots:
     void updateCompleter();
     void gathererThreadFinished();
@@ -274,6 +290,7 @@ class CORE_EXPORT QgsFeatureFilterModel : public QAbstractItemModel
     QTimer mReloadTimer;
     bool mShouldReloadCurrentFeature = false;
     bool mExtraValueDoesNotExist = false;
+    bool mAllowNull = false;
 
     QString mIdentifierField;
 

src/gui/editorwidgets/qgsrelationreferencewidget.cpp

@@ -677,8 +677,7 @@ void QgsRelationReferenceWidget::mapIdentification()
 
 void QgsRelationReferenceWidget::comboReferenceChanged( int index )
 {
-  QgsFeatureId fid = mComboBox->itemData( index, QgsAttributeTableModel::FeatureIdRole ).value<QgsFeatureId>();
-  mReferencedLayer->getFeatures( QgsFeatureRequest().setFilterFid( fid ) ).nextFeature( mFeature );
+  mReferencedLayer->getFeatures( mComboBox->currentFeatureRequest() ).nextFeature( mFeature );
   highlightFeature( mFeature );
   updateAttributeEditorFrame( mFeature );
   emit foreignKeyChanged( mFeature.attribute( mReferencedFieldIdx ) );

src/gui/qgsfeaturelistcombobox.cpp

@@ -38,13 +38,15 @@ QgsFeatureListComboBox::QgsFeatureListComboBox( QWidget *parent )
   connect( mModel, &QgsFeatureFilterModel::filterExpressionChanged, this, &QgsFeatureListComboBox::filterExpressionChanged );
   connect( mModel, &QgsFeatureFilterModel::isLoadingChanged, this, &QgsFeatureListComboBox::onLoadingChanged );
   connect( mModel, &QgsFeatureFilterModel::filterJobCompleted, this, &QgsFeatureListComboBox::onFilterUpdateCompleted );
+  connect( mModel, &QgsFeatureFilterModel::allowNullChanged, this, &QgsFeatureListComboBox::allowNullChanged );
   connect( mModel, &QgsFeatureFilterModel::extraIdentifierValueChanged, this, &QgsFeatureListComboBox::identifierValueChanged );
   connect( mModel, &QgsFeatureFilterModel::extraIdentifierValueIndexChanged, this, &QgsFeatureListComboBox::setCurrentIndex );
   connect( mModel, &QgsFeatureFilterModel::identifierFieldChanged, this, &QgsFeatureListComboBox::identifierFieldChanged );
   connect( mCompleter, static_cast<void( QCompleter::* )( const QModelIndex & )>( &QCompleter::highlighted ), this, &QgsFeatureListComboBox::onItemSelected );
   connect( mCompleter, static_cast<void( QCompleter::* )( const QModelIndex & )>( &QCompleter::activated ), this, &QgsFeatureListComboBox::onActivated );
   connect( mModel, &QgsFeatureFilterModel::beginUpdate, this, &QgsFeatureListComboBox::storeLineEditState );
   connect( mModel, &QgsFeatureFilterModel::endUpdate, this, &QgsFeatureListComboBox::restoreLineEditState );
+  connect( mModel, &QgsFeatureFilterModel::dataChanged, this, &QgsFeatureListComboBox::onDataChanged );
 
   connect( this, static_cast<void( QgsFeatureListComboBox::* )( int )>( &QgsFeatureListComboBox::currentIndexChanged ), this, &QgsFeatureListComboBox::onCurrentIndexChanged );
 
@@ -55,10 +57,7 @@ QgsFeatureListComboBox::QgsFeatureListComboBox( QWidget *parent )
 
   connect( mLineEdit, &QgsFilterLineEdit::textEdited, this, &QgsFeatureListComboBox::onCurrentTextChanged );
 
-  connect( mLineEdit, &QgsFilterLineEdit::textChanged, this, []( const QString & text )
-  {
-    QgsDebugMsg( QStringLiteral( "Edit text changed to %1" ).arg( text ) );
-  } );
+  setToolTip( tr( "Just start typing what you are looking for." ) );
 }
 
 QgsVectorLayer *QgsFeatureListComboBox::sourceLayer() const
@@ -83,6 +82,7 @@ void QgsFeatureListComboBox::setDisplayExpression( const QString &expression )
 
 void QgsFeatureListComboBox::onCurrentTextChanged( const QString &text )
 {
+  mIsCurrentlyEdited = true;
   mPopupRequested = true;
   mModel->setFilterValue( text );
 }
@@ -107,6 +107,7 @@ void QgsFeatureListComboBox::onItemSelected( const QModelIndex &index )
 
 void QgsFeatureListComboBox::onCurrentIndexChanged( int i )
 {
+  mIsCurrentlyEdited = false;
   QModelIndex modelIndex = mModel->index( i, 0, QModelIndex() );
   mModel->setExtraIdentifierValue( mModel->data( modelIndex, QgsFeatureFilterModel::IdentifierValueRole ) );
   mLineEdit->setText( mModel->data( modelIndex, QgsFeatureFilterModel::ValueRole ).toString() );
@@ -115,19 +116,33 @@ void QgsFeatureListComboBox::onCurrentIndexChanged( int i )
 void QgsFeatureListComboBox::onActivated( QModelIndex modelIndex )
 {
   setIdentifierValue( mModel->data( modelIndex, QgsFeatureFilterModel::IdentifierValueRole ) );
-  QgsDebugMsg( QStringLiteral( "Activated index" ) );
-  QgsDebugMsg( QStringLiteral( "%1 %2" ).arg( QString::number( modelIndex.row() ), mModel->data( modelIndex, QgsFeatureFilterModel::ValueRole ).toString() ) );
   mLineEdit->setText( mModel->data( modelIndex, QgsFeatureFilterModel::ValueRole ).toString() );
 }
 
 void QgsFeatureListComboBox::storeLineEditState()
 {
-  mLineEditState.store( mLineEdit );
+  if ( mIsCurrentlyEdited )
+    mLineEditState.store( mLineEdit );
 }
 
 void QgsFeatureListComboBox::restoreLineEditState()
 {
-  mLineEditState.restore( mLineEdit );
+  if ( mIsCurrentlyEdited )
+    mLineEditState.restore( mLineEdit );
+}
+
+void QgsFeatureListComboBox::onDataChanged( const QModelIndex &topLeft, const QModelIndex &bottomRight, const QVector<int> &roles )
+{
+  Q_UNUSED( roles )
+  if ( !mIsCurrentlyEdited )
+  {
+    const int currentIndex = mModel->extraIdentifierValueIndex();
+    if ( currentIndex >= topLeft.row() && currentIndex <= bottomRight.row() )
+    {
+      QModelIndex modelIndex = mModel->index( currentIndex, 0, QModelIndex() );
+      mLineEdit->setText( mModel->data( modelIndex, QgsFeatureFilterModel::ValueRole ).toString() );
+    }
+  }
 }
 
 QString QgsFeatureListComboBox::identifierField() const
@@ -163,16 +178,12 @@ void QgsFeatureListComboBox::keyPressEvent( QKeyEvent *event )
 
 bool QgsFeatureListComboBox::allowNull() const
 {
-  return mAllowNull;
+  return mModel->allowNull();
 }
 
 void QgsFeatureListComboBox::setAllowNull( bool allowNull )
 {
-  if ( mAllowNull == allowNull )
-    return;
-
-  mAllowNull = allowNull;
-  emit allowNullChanged();
+  mModel->setAllowNull( allowNull );
 }
 
 QVariant QgsFeatureListComboBox::identifierValue() const
@@ -187,7 +198,10 @@ void QgsFeatureListComboBox::setIdentifierValue( const QVariant &identifierValue
 
 QgsFeatureRequest QgsFeatureListComboBox::currentFeatureRequest() const
 {
-  return QgsFeatureRequest().setFilterExpression( QStringLiteral( "%1 = %2" ).arg( QgsExpression::quotedColumnRef( mModel->identifierField() ), QgsExpression::quotedValue( mModel->extraIdentifierValue() ) ) );
+  if ( mModel->extraIdentifierValue().isNull() )
+    return QgsFeatureRequest().setFilterFids( QgsFeatureIds() ); // NULL: Return a request that's guaranteed to not return anything
+  else
+    return QgsFeatureRequest().setFilterExpression( QStringLiteral( "%1 = %2" ).arg( QgsExpression::quotedColumnRef( mModel->identifierField() ), QgsExpression::quotedValue( mModel->extraIdentifierValue() ) ) );
 }
 
 QString QgsFeatureListComboBox::filterExpression() const

src/gui/qgsfeaturelistcombobox.h

@@ -48,6 +48,7 @@ class GUI_EXPORT QgsFeatureListComboBox : public QComboBox
     Q_PROPERTY( bool allowNull READ allowNull WRITE setAllowNull NOTIFY allowNullChanged )
 
   public:
+
     /**
      * Create a new QgsFeatureListComboBox, optionally specifying a \a parent.
      */
@@ -109,8 +110,6 @@ class GUI_EXPORT QgsFeatureListComboBox : public QComboBox
 
     /**
      * Determines if a NULL value should be available in the list.
-     *
-     * TODO!
      */
     bool allowNull() const;
 
@@ -185,6 +184,7 @@ class GUI_EXPORT QgsFeatureListComboBox : public QComboBox
     void onActivated( QModelIndex index );
     void storeLineEditState();
     void restoreLineEditState();
+    void onDataChanged( const QModelIndex &topLeft, const QModelIndex &bottomRight, const QVector<int> &roles = QVector<int>() );
 
   private:
     struct LineEditState
@@ -202,7 +202,6 @@ class GUI_EXPORT QgsFeatureListComboBox : public QComboBox
     QCompleter *mCompleter;
     QString mDisplayExpression;
     QgsFilterLineEdit *mLineEdit;
-    bool mAllowNull = true;
     bool mPopupRequested = false;
     bool mIsCurrentlyEdited = false;
     LineEditState mLineEditState;