[Qgis-developer] Adding features with an editing buffer - undo action unavailable in the GUI?

Martin Dobias wonder.sk at gmail.com
Tue May 22 12:35:59 PDT 2012

On Mon, May 21, 2012 at 1:26 AM, Ricardo Filipe Soares Garcia da
<ricardo.garcia.silva at gmail.com> wrote:
> Hi list
> I am writing a plugin that creates new features. According to the
> pyqgis cookbook[0], and the API docs[1], when I call the addFeatures
> method on a QgsVectorLayer, the features should get added to the
> layers editing buffer. It is my understanding that this action ought
> to be undo-able, since the changes haven't been commited yet. But the
> undo icon in the QGIS GUI doesn't seem to be aware of the changes that
> the plugin is making to the layer. Do I have to hook up the changes to
> the undo/redo stack myself? How can I do this?

Ooops, it seems that some documentation is missing! I have just added
some notes to PyQGIS cookbook, hope that helps:

> Also, when I press the 'toggle editing' button in the digitizing
> toolbar, in order to save the changes I am getting a strange
> behaviour:
> - If I choose to save my changes, everything goes fine,
> - If I choose to close without saving, QGIS crashes with:
> Fatal: ASSERT: "mAddedFeatures.isEmpty()" in file
> /home/ricardo/dev/Quantum-GIS/src/core/qgsvectorlayer.cpp, line 3982

That's a check to ensure that the undo stack is working properly - it
will not crash if you wrap it into the edit commands.


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