Add method to reset vector layer for data defined button

Author: nyalldawson

python/gui/qgsdatadefinedbutton.sip

@@ -94,6 +94,13 @@ class QgsDataDefinedButton : QToolButton
      */
     QgsDataDefined currentDataDefined() const;
 
+    /** Sets the vector layer associated with the button. This controls which fields are
+     * displayed within the widget's pop up menu.
+     * @param layer vector layer
+     * @note added in QGIS 3.0
+     */
+    void setVectorLayer( QgsVectorLayer* layer );
+
     /**
      * Whether the current data definition or expression is to be used
      */

src/gui/qgsdatadefinedbutton.cpp

@@ -195,7 +195,6 @@ void QgsDataDefinedButton::init( const QgsVectorLayer* vl,
     mActionDataTypes->setText( tr( "Field type: " ) + mDataTypesString );
   }
 
-  updateFieldLists();
   updateGui();
 }
 
@@ -218,6 +217,11 @@ QgsDataDefined QgsDataDefinedButton::currentDataDefined() const
   return dd;
 }
 
+void QgsDataDefinedButton::setVectorLayer( QgsVectorLayer* layer )
+{
+  mVectorLayer = layer;
+}
+
 void QgsDataDefinedButton::mouseReleaseEvent( QMouseEvent *event )
 {
   // Ctrl-click to toggle activated state

src/gui/qgsdatadefinedbutton.h

@@ -127,6 +127,13 @@ class GUI_EXPORT QgsDataDefinedButton: public QToolButton
      */
     QgsDataDefined currentDataDefined() const;
 
+    /** Sets the vector layer associated with the button. This controls which fields are
+     * displayed within the widget's pop up menu.
+     * @param layer vector layer
+     * @note added in QGIS 3.0
+     */
+    void setVectorLayer( QgsVectorLayer* layer );
+
     /**
      * Whether the current data definition or expression is to be used
      */