Do not cache expression nodes with eval errors

m-kuhn · m-kuhn · commit aa3bfff7a85c · 2017-12-27T19:53:10.000+01:00
When there is an evaluation error in an expression, there is no need to cache results.
With the previous approach, sometimes eval errors were not reported because the error was set to false (Null), evaluation triggered again but it didn't report any more eval errors because it was relying on cached values.
diff --git a/src/core/expression/qgsexpressionnode.cpp b/src/core/expression/qgsexpressionnode.cpp
@@ -14,6 +14,7 @@
  ***************************************************************************/
 
 #include "qgsexpressionnode.h"
+#include "qgsexpression.h"
 
 
 QVariant QgsExpressionNode::eval( QgsExpression *parent, const QgsExpressionContext *context )
@@ -34,7 +35,10 @@ bool QgsExpressionNode::prepare( QgsExpression *parent, const QgsExpressionConte
   if ( isStatic( parent, context ) )
   {
     mCachedStaticValue = evalNode( parent, context );
-    mHasCachedValue = true;
+    if ( !parent->hasEvalError() )
+      mHasCachedValue = true;
+    else
+      mHasCachedValue = false;
     return true;
   }
   else
