Don't store a long-term expression for atlas file name

qgis · Feb 11, 2021 · e90ebb7 · e90ebb7
1 parent 2e1fea6
commit e90ebb7
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Showing 2 changed files with 14 additions and 10 deletions.
diff --git a/src/core/layout/qgslayoutatlas.cpp b/src/core/layout/qgslayoutatlas.cpp
@@ -536,17 +536,17 @@ bool QgsLayoutAtlas::updateFilenameExpression( QString &error )
 
   if ( !mFilenameExpressionString.isEmpty() )
   {
-    mFilenameExpression = QgsExpression( mFilenameExpressionString );
+    QgsExpression filenameExpression( mFilenameExpressionString );
     // expression used to evaluate each filename
     // test for evaluation errors
-    if ( mFilenameExpression.hasParserError() )
+    if ( filenameExpression.hasParserError() )
     {
-      error = mFilenameExpression.parserErrorString();
+      error = filenameExpression.parserErrorString();
       return false;
     }
 
     // prepare the filename expression
-    evalResult = mFilenameExpression.prepare( &expressionContext );
+    evalResult = filenameExpression.prepare( &expressionContext );
   }
 
   // regenerate current filename
@@ -557,7 +557,7 @@ bool QgsLayoutAtlas::updateFilenameExpression( QString &error )
 
   if ( ! evalResult )
   {
-    error = mFilenameExpression.evalErrorString();
+    error = mFilenameExpressionError;
   }
 
   return evalResult;
@@ -566,12 +566,16 @@ bool QgsLayoutAtlas::updateFilenameExpression( QString &error )
 bool QgsLayoutAtlas::evalFeatureFilename( const QgsExpressionContext &context )
 {
   //generate filename for current atlas feature
-  if ( !mFilenameExpressionString.isEmpty() && mFilenameExpression.isValid() )
+  mFilenameExpressionError.clear();
+  if ( !mFilenameExpressionString.isEmpty() )
   {
-    QVariant filenameRes = mFilenameExpression.evaluate( &context );
-    if ( mFilenameExpression.hasEvalError() )
+    QgsExpression filenameExpression( mFilenameExpressionString );
+    filenameExpression.prepare( &context );
+    QVariant filenameRes = filenameExpression.evaluate( &context );
+    if ( filenameExpression.hasEvalError() )
     {
-      QgsMessageLog::logMessage( tr( "Atlas filename evaluation error: %1" ).arg( mFilenameExpression.evalErrorString() ), tr( "Layout" ) );
+      mFilenameExpressionError = filenameExpression.evalErrorString();
+      QgsMessageLog::logMessage( tr( "Atlas filename evaluation error: %1" ).arg( filenameExpression.evalErrorString() ), tr( "Layout" ) );
       return false;
     }
 

diff --git a/src/core/layout/qgslayoutatlas.h b/src/core/layout/qgslayoutatlas.h
@@ -366,8 +366,8 @@ class CORE_EXPORT QgsLayoutAtlas : public QObject, public QgsAbstractLayoutItera
     bool mEnabled = false;
     bool mHideCoverage = false;
     QString mFilenameExpressionString;
+    QString mFilenameExpressionError;
 
-    QgsExpression mFilenameExpression;
     QgsVectorLayerRef mCoverageLayer;
 
     QString mCurrentFilename;