Bug report #14490: QgsMapLayer::dataChanged not emited when QgsVectorLayer data are modified - QGIS Application - QGIS Issue Tracking

Bug report #14490

QgsMapLayer::dataChanged not emited when QgsVectorLayer data are modified

Added by Vincent Mora over 8 years ago. Updated over 5 years ago.

Status:	Closed
Priority:	Normal
Assignee:	-
Category:	Data Provider
Affected QGIS version:	2.8.3	Regression?:	No
Operating System:		Easy fix?:	No
Pull Request or Patch supplied:	No	Resolution:	end of life
Crashes QGIS or corrupts data:	No	Copied to github as #:	22466

Description

To reproduce activate a vector layer, and in the in the python console:

def prt():
    print "changed" 
iface.activeLayer().dataChanged.connect(prt)

Open the attribute table and change an attribute, save -> nothing

iface.activeLayer().editingStopped.connect(prt)

Works instead, but it's not really the first thing that comes to mind (actually it only came to mine by looking at QgsVectorLayer::commitChanges source code).

History

#1 Updated by Giovanni Manghi over 8 years ago

Category set to Python plugins

#2 Updated by Hugo Mercier over 8 years ago

Status changed from Open to Feedback
Category changed from Python plugins to Data Provider

Indeed. Also observed on 2.15

Actually, this dataChanged signal seems to be used only on setSubsetString() of each provider ...
There is also a layerModified signal which is only emitted when attribute aliases are created or removed ...

A "something has changed" signal (for feature addition/removal/modification) could be helpful.

What about choosing only one signal and emitting it when one of the other modification signals is emitted ? (maybe for qgis 3.0)