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I often have to reload layers in the layers panel after doing changes in the DB-Manager (add a column, delete a default value, ...). At the moment I use the changeDatasource plugin. Can this also be done using Python?

Germán Carrillo
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eclipsed_by_the_moon
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3 Answers3

7

if you have your layer as a variable, simply layer.reload()

You can obtain a list of all layers of the current project from QgsMapLayerRegistry.instance().mapLayers()

If you don’t care about reloading all other layers at the same time, the one-liner

QgsMapLayerRegistry.instance().reloadAllLayers()

does the job, too.

References:

christoph
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  • Running QgsMapLayerRegistry.instance().reloadAllLayers() in the Python console returns an error: Traceback (most recent call last): File "/usr/lib/python3.5/code.py", line 91, in runcode exec(code, self.locals) File "<input>", line 1, in <module> NameError: name 'QgsMapLayerRegistry' is not defined – eclipsed_by_the_moon Jan 28 '17 at 20:28
  • layer = qgis.utils.iface.mapCanvas().currentLayer() layer.reload() doesn't work. – eclipsed_by_the_moon Jan 28 '17 at 20:39
  • in the Python console iface.mapCanvas().currentLayer().reload() should work – checking it here in a moment – christoph Jan 29 '17 at 17:13
  • It works as long as a layer is selected in the layer list (QgsMapCanvas refers to to the user interface, QgsMapLayerRegistry to the QGIS project)

    QgsMapLayerRegistry.instance().reloadAllLayers() works as expected, too.

     – christoph Jan 29 '17 at 21:34
  • Perhaps it's a QGIS 2.x/3.x issue. I'll test this in QGIS 2.18 tomorrow. – eclipsed_by_the_moon Jan 30 '17 at 09:27
  • For testing purposes I've added a new column in the DB-Manager. The Python console (QGIS 2.18.3) returns no errors running your statements but nothing happens. The new column is still not listed in the attribute table. I'm not sure what i'm doing wrong. – eclipsed_by_the_moon Jan 31 '17 at 09:10
  • Ah, ok, that’s a restriction of QGIS. It does not refresh the structure of the dataset, but only its content. Compare http://gis.stackexchange.com/questions/190440/how-to-refresh-the-attribute-table-of-a-layer-after-editing-the-table-in-the-db/190798 – christoph Jan 31 '17 at 17:17
  • try layer.dataProvider().setDataSourceUri(layer.dataProvider().dataSourceUri()) – christoph Jan 31 '17 at 17:23
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QgsProject.instance().reloadAllLayers() worked for me on QGIS 3.10.

Kadir Şahbaz
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Romário Carvalho Neto
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  • Welcome to GIS SE! As a new user please take the [tour]. A good answer should include details about how to use your suggestion and info about what it does. Please [edit] your answer to add additional info. – Midavalo Apr 09 '21 at 15:32
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I've read several answers for this specific question; none of them seems to work. The only effective solution I could find is:

layer.setDataSource( layer.source(), layer.name(), layer.providerType() )

Tested in QGIS v2.14.8.

Germán Carrillo
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