Add warning when no output file selected in the Merge tool in fTools. Fix #3210

git-svn-id: http://svn.osgeo.org/qgis/trunk/qgis@14634 c8812cc2-4d05-0410-92ff-de0c093fc19c

Author: alexbruy

python/plugins/fTools/tools/doMergeShapes.py

@@ -18,6 +18,7 @@ def __init__( self, iface ):
 
     self.mergeThread = None
     self.inputFiles = None
+    self.outFileName = None
 
     self.btnOk = self.buttonBox.button( QDialogButtonBox.Ok )
     self.btnClose = self.buttonBox.button( QDialogButtonBox.Close )
@@ -96,6 +97,11 @@ def accept( self ):
 
       self.progressFiles.setRange( 0, self.inputFiles.count() )
 
+    if self.outFileName is None:
+      QMessageBox.warning( self, self.tr( "No output file" ),
+        self.tr( "Please specify output file." ) )
+      return
+
     outFile = QFile( self.outFileName )
     if outFile.exists():
       if not QgsVectorFileWriter.deleteShapeFile( self.outFileName ):