I'm making a plugin that converts vector .shp to raster .tif. This is the UI of the plugin. The ComboBox is the custom mMapLayerComboBox widget.

UI of the Plugin

  1. After selecting a loaded shapefile in QGIS, what is the type of the layer object that I'll use in the python code as a shapefile? This is the code:

enter image description here

Also, OSGEO/OGR/GDAL needs a string as an argument (the pathfile of the shapefile to be exact) as input. So ogr.Open(layer) gives an error. This is the error:

Not a String error

But running ogr.Open(layer) in Jupyter, where layer = 'datasets/input/Agriculture.shp' gives no error and runs the code properly.

So, 2. How do I get the pathfile of the shapefile from the ComboBox? (if not ComboBox, what other widgets can I use)?

  • Could you add the code and the error message as text instead of image? Commented Jan 31, 2020 at 23:17

1 Answer 1


In this case, layer is an instance of QgsVectorLayer, because currentLayer gives you that. But ogr.Open() needs a path. So you need to get layer source to pass to ogr.Open(). QgsVectorLayer class has source method which gives you full path of the layer source.

Use in that way:

layer = self.dlg.mMapLayerComboBox.currentLayer()
layer_path = layer.source()

dataSource = ogr.Open(layer_path)
ogr_layer = dataSource.GetLayer()
  • Yes, this works, but mMapLayerComboBox doesn't have source as a method, an error came when I used. used normal comboBox with which it now works. Thanks a lot! Commented Feb 1, 2020 at 17:41
  • 1
    QgsMapLayerComboBox doesn't have source method. It's QgsMapLayer's method. mMapLayerComboBox.currentLayer() returns a QgsMapLayer instance (means layer). Commented Feb 1, 2020 at 19:40

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