Ensure using @geometry/@feature variables trigger geometry fetching

in expression calculation Fixes #50791
qgis · Feb 1, 2023 · 9fb0da4 · 9fb0da4
1 parent 903ce1d
commit 9fb0da4
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diff --git a/src/core/expression/qgsexpressionfunction.cpp b/src/core/expression/qgsexpressionfunction.cpp
@@ -201,6 +201,11 @@ bool QgsStaticExpressionFunction::usesGeometry( const QgsExpressionNodeFunction
     return mUsesGeometry;
 }
 
+void QgsStaticExpressionFunction::setUsesGeometryFunction( const std::function<bool ( const QgsExpressionNodeFunction * )> &usesGeometry )
+{
+  mUsesGeometryFunc = usesGeometry;
+}
+
 QSet<QString> QgsStaticExpressionFunction::referencedColumns( const QgsExpressionNodeFunction *node ) const
 {
   if ( mReferencedColumnsFunc )
@@ -8415,6 +8420,21 @@ const QList<QgsExpressionFunction *> &QgsExpression::Functions()
       return false;
     }
     );
+    varFunction->setUsesGeometryFunction(
+      []( const QgsExpressionNodeFunction * node ) -> bool
+    {
+      if ( node && node->args()->count() > 0 )
+      {
+        QgsExpressionNode *argNode = node->args()->at( 0 );
+        if ( QgsExpressionNodeLiteral *literal = dynamic_cast<QgsExpressionNodeLiteral *>( argNode ) )
+        {
+          if ( literal->value() == QLatin1String( "geometry" ) || literal->value() == QLatin1String( "feature" ) )
+            return true;
+        }
+      }
+      return false;
+    }
+    );
 
     functions
         << varFunction;

diff --git a/src/core/expression/qgsexpressionfunction.h b/src/core/expression/qgsexpressionfunction.h
@@ -473,6 +473,13 @@ class QgsStaticExpressionFunction : public QgsExpressionFunction
 
     bool usesGeometry( const QgsExpressionNodeFunction *node ) const override;
 
+    /**
+     * Set a function that will be called when determining if the function requires feature geometry or not.
+     *
+     * \since QGIS 3.30
+     */
+    void setUsesGeometryFunction( const std::function< bool( const QgsExpressionNodeFunction *node )> &usesGeometry );
+
     QSet<QString> referencedColumns( const QgsExpressionNodeFunction *node ) const override;
 
     bool isStatic( const QgsExpressionNodeFunction *node, QgsExpression *parent, const QgsExpressionContext *context ) const override;
@@ -487,6 +494,7 @@ class QgsStaticExpressionFunction : public QgsExpressionFunction
      */
     void setIsStaticFunction( const std::function< bool ( const QgsExpressionNodeFunction *, QgsExpression *, const QgsExpressionContext * ) > &isStatic );
 
+
     /**
      * Tag this function as either static or not static.
      * This will indicate that the function is always expected to return the same value for

diff --git a/tests/src/core/testqgsexpression.cpp b/tests/src/core/testqgsexpression.cpp
@@ -2322,6 +2322,7 @@ class TestQgsExpression: public QObject
 
       // newer form
       QgsExpression exp2( QStringLiteral( "@feature" ) );
+      QVERIFY( exp2.needsGeometry() );
       v = exp2.evaluate( &context );
       evalFeature = v.value<QgsFeature>();
       QCOMPARE( evalFeature.id(), f.id() );
@@ -2344,6 +2345,7 @@ class TestQgsExpression: public QObject
 
       // newer form
       QgsExpression exp2( QStringLiteral( "geom_to_wkt(@geometry)" ) );
+      QVERIFY( exp2.needsGeometry() );
       v = exp2.evaluate( &contextWithGeometry );
       QCOMPARE( v.toString(), QStringLiteral( "Point (1 2)" ) );
       v = exp2.evaluate( &contextWithNoGeometry );