Updating layer extent after changing source in PyQGIS?

Question

I am running a python script in QGIS 3.8.3-Zanzibar where I am changing the source of a GeoJson file.

I am calling layer.reload() but subsequent calls to layer.extent() still return the old extent. I can open the attribute table and zoom to the location and see the selected outline.

But the actual layer symbol does not display.

Things that I've tried:

1. I turned off canvas caching to rule that out.

2. I have tried these statements (in a variety of combinations):

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

I figure I'm missing something easy.

Answer 1

This works for me:

if iface.mapCanvas().isCachingEnabled():
    lyr.triggerRepaint()
else:
    iface.mapCanvas().refresh()

Answer 2

To update the extents of a layer after making any changes to its data source, use the QgsVectorLayer::updateExtents() method:

layer.updateExtents()