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I need an invalid layer to test a plugin in QGIS. In the plugin window, I select a layer from combobox. So, the invalid layer should be in the Layers panel. I google for a while but I cannot find a way to generate an invalid vector layer.

How can I generate one so that layer.isValid() returns False?

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  • Did you try self crossing lines, polygons? See also here (at the bottom of the paragraph): docs.qgis.org/3.10/en/docs/user_manual/plugins/core_plugins/…
    – Babel
    Commented Dec 18, 2020 at 12:59
  • @babel, Doesn't it create an invalid geometry instead of an invalid layer?
    – Kadir Şahbaz
    Commented Dec 18, 2020 at 13:01
  • OK, you're probably right. Could you just create any kind of geopackage, than open it in a text editor, add or delete a few characters, thus making it invalid? Not sure if that is what you want.
    – Babel
    Commented Dec 18, 2020 at 13:03
  • @babel Thanks for the trick. This method genereate an invalid data. But in this case, I cannot add the data to Layers panel. I've added more information.
    – Kadir Şahbaz
    Commented Dec 18, 2020 at 14:12
  • 1
    A good source of "unusual" data can usually be found in the software tests (see the Github repo)
    – JGH
    Commented Dec 18, 2020 at 15:21

2 Answers 2

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  • Providing an invalid path makes it invalid: layer = QgsVectorLayer("zxcxzcxc/home/bera/GIS/Data/testdata/ak_riks.shp", "testlayer_shp", "ogr")
  • Or a providerlib that doesnt exist: layer = QgsVectorLayer("/home/bera/GIS/Data/testdata/ak_riks.shp", "testlayer_shp", "O G R"), it should be "ogr"

Then add layer to the project:

QgsProject.instance().addMapLayer(layer)

enter image description here

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Using QgsVectorLayer without parameters generates an invalid vector layer.

layer = QgsVectorLayer()
print(layer)
# OUT:
# <QgsVectorLayer: '' (Invalid)>

QgsProject.instance().addMapLayer(layer)

enter image description here

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