Add an isField test for QgsExpression

Checks whether expression consists of solely a field reference
qgis · Apr 27, 2015 · d431962 · d431962
1 parent ffeb61d
commit d431962
Show file tree

Hide file tree

Showing 3 changed files with 20 additions and 0 deletions.
diff --git a/python/core/qgsexpression.sip b/python/core/qgsexpression.sip
@@ -72,6 +72,11 @@ class QgsExpression
     //! @note added in 2.2
     static bool hasSpecialColumn( const QString& name );
 
+    /** Checks whether an expression consists only of a single field reference
+     * @note added in 2.9
+     */
+    bool isField() const;
+
     static bool isValid( const QString& text, const QgsFields& fields, QString &errorMessage );
 
     void setScale( double scale );

diff --git a/src/core/qgsexpression.h b/src/core/qgsexpression.h
@@ -155,6 +155,11 @@ class CORE_EXPORT QgsExpression
     //! @note added in 2.2
     static bool hasSpecialColumn( const QString& name );
 
+    /** Checks whether an expression consists only of a single field reference
+     * @note added in 2.9
+     */
+    bool isField() const { return rootNode() && dynamic_cast<const NodeColumnRef*>( rootNode() ) ;}
+
     static bool isValid( const QString& text, const QgsFields& fields, QString &errorMessage );
 
     void setScale( double scale ) { mScale = scale; }

diff --git a/tests/src/core/testqgsexpression.cpp b/tests/src/core/testqgsexpression.cpp
@@ -1099,6 +1099,16 @@ class TestQgsExpression: public QObject
       QCOMPARE( QgsExpression::evaluateToDouble( QString( "a" ), 9.0 ), 9.0 );
       QCOMPARE( QgsExpression::evaluateToDouble( QString(), 9.0 ), 9.0 );
     }
+
+    void eval_isField()
+    {
+      QCOMPARE( QgsExpression( "" ).isField(), false );
+      QCOMPARE( QgsExpression( "42" ).isField(), false );
+      QCOMPARE( QgsExpression( "foo" ).isField(), true );
+      QCOMPARE( QgsExpression( "\"foo bar\"" ).isField(), true );
+      QCOMPARE( QgsExpression( "sqrt(foo)" ).isField(), false );
+      QCOMPARE( QgsExpression( "foo + bar" ).isField(), false );
+    }
 };
 
 QTEST_MAIN( TestQgsExpression )