From d11e66749b2c1b2f830de7ae8274d65b97878dac Mon Sep 17 00:00:00 2001
From: Nyall Dawson <nyall.dawson@gmail.com>
Date: Wed, 24 Feb 2016 11:32:54 +1100
Subject: [PATCH] Quote fields in size/width assistant (fix #14257)

---
 python/gui/qgsfieldexpressionwidget.sip       |  7 +++++
 src/gui/qgsfieldexpressionwidget.cpp          |  5 ++++
 src/gui/qgsfieldexpressionwidget.h            |  7 +++++
 src/gui/symbology-ng/qgssizescalewidget.cpp   |  2 +-
 .../src/gui/testqgsfieldexpressionwidget.cpp  | 28 +++++++++++++++++++
 5 files changed, 48 insertions(+), 1 deletion(-)

diff --git a/python/gui/qgsfieldexpressionwidget.sip b/python/gui/qgsfieldexpressionwidget.sip
index 81de081165d..5644260c1f9 100644
--- a/python/gui/qgsfieldexpressionwidget.sip
+++ b/python/gui/qgsfieldexpressionwidget.sip
@@ -46,6 +46,13 @@ class QgsFieldExpressionWidget : QWidget
       */
     QString currentText() const;
 
+    /** Returns the currently selected field or expression. If a field is currently selected, the returned
+     * value will be converted to a valid expression referencing this field (ie enclosing the field name with
+     * appropriate quotations).
+     * @note added in QGIS 2.14
+     */
+    QString asExpression() const;
+
     //! Returns the currently used layer
     QgsVectorLayer* layer() const;
 
diff --git a/src/gui/qgsfieldexpressionwidget.cpp b/src/gui/qgsfieldexpressionwidget.cpp
index 150de1c283f..4b35ec7815d 100644
--- a/src/gui/qgsfieldexpressionwidget.cpp
+++ b/src/gui/qgsfieldexpressionwidget.cpp
@@ -103,6 +103,11 @@ QString QgsFieldExpressionWidget::currentText() const
   return mCombo->currentText();
 }
 
+QString QgsFieldExpressionWidget::asExpression() const
+{
+  return isExpression() ? currentText() : QgsExpression::quotedColumnRef( currentText() );
+}
+
 bool QgsFieldExpressionWidget::isValidExpression( QString *expressionError ) const
 {
   QString temp;
diff --git a/src/gui/qgsfieldexpressionwidget.h b/src/gui/qgsfieldexpressionwidget.h
index 16e8c77d125..873110a627c 100644
--- a/src/gui/qgsfieldexpressionwidget.h
+++ b/src/gui/qgsfieldexpressionwidget.h
@@ -89,6 +89,13 @@ class GUI_EXPORT QgsFieldExpressionWidget : public QWidget
       */
     QString currentText() const;
 
+    /** Returns the currently selected field or expression. If a field is currently selected, the returned
+     * value will be converted to a valid expression referencing this field (ie enclosing the field name with
+     * appropriate quotations).
+     * @note added in QGIS 2.14
+     */
+    QString asExpression() const;
+
     //! Returns the currently used layer
     QgsVectorLayer* layer() const;
 
diff --git a/src/gui/symbology-ng/qgssizescalewidget.cpp b/src/gui/symbology-ng/qgssizescalewidget.cpp
index cd6a65e34c4..12b92b3200f 100644
--- a/src/gui/symbology-ng/qgssizescalewidget.cpp
+++ b/src/gui/symbology-ng/qgssizescalewidget.cpp
@@ -222,7 +222,7 @@ void QgsSizeScaleWidget::showEvent( QShowEvent* )
 QgsScaleExpression *QgsSizeScaleWidget::createExpression() const
 {
   return new QgsScaleExpression( QgsScaleExpression::Type( scaleMethodComboBox->itemData( scaleMethodComboBox->currentIndex() ).toInt() ),
-                                 mExpressionWidget->currentField(),
+                                 mExpressionWidget->asExpression(),
                                  minValueSpinBox->value(),
                                  maxValueSpinBox->value(),
                                  minSizeSpinBox->value(),
diff --git a/tests/src/gui/testqgsfieldexpressionwidget.cpp b/tests/src/gui/testqgsfieldexpressionwidget.cpp
index 8305074485c..bdf78f53de2 100644
--- a/tests/src/gui/testqgsfieldexpressionwidget.cpp
+++ b/tests/src/gui/testqgsfieldexpressionwidget.cpp
@@ -48,6 +48,7 @@ class TestQgsFieldExpressionWidget : public QObject
     void cleanup();           // will be called after every testfunction.
 
     void testRemoveJoin();
+    void asExpression();
 
   private:
     QgsFieldExpressionWidget* mWidget;
@@ -133,6 +134,33 @@ void TestQgsFieldExpressionWidget::testRemoveJoin()
   // QVERIFY( !isValid ); TODO: the expression should not be valid anymore since the field doesn't exist anymore. Maybe we need a new expression method to get more details.
 }
 
+void TestQgsFieldExpressionWidget::asExpression()
+{
+  QgsVectorLayer* layer = new QgsVectorLayer( "point?field=fld:int&field=fld2:int&field=fld3:int", "x", "memory" );
+  QgsMapLayerRegistry::instance()->addMapLayer( layer );
+
+  QScopedPointer< QgsFieldExpressionWidget > widget( new QgsFieldExpressionWidget() );
+  widget->setLayer( layer );
+
+  // check with field set
+  widget->setField( "fld" );
+  QCOMPARE( widget->asExpression(), QString( "\"fld\"" ) );
+
+  // check with expressions set
+  widget->setField( "fld + 1" );
+  QCOMPARE( widget->asExpression(), QString( "fld + 1" ) );
+  widget->setField( "1" );
+  QCOMPARE( widget->asExpression(), QString( "1" ) );
+  widget->setField( "\"fld2\"" );
+  QCOMPARE( widget->asExpression(), QString( "\"fld2\"" ) );
+
+  // check switching back to a field
+  widget->setField( "fld3" );
+  QCOMPARE( widget->asExpression(), QString( "\"fld3\"" ) );
+
+  QgsMapLayerRegistry::instance()->removeMapLayer( layer );
+}
+
 
 QTEST_MAIN( TestQgsFieldExpressionWidget )
 #include "testqgsfieldexpressionwidget.moc"