[Qgis-developer] Get list of dirty features and their attributes

[Ivan Minčík]

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On 11/30/2012 03:45 PM, Martin Dobias wrote:
> Hi Ivan
> 
> On Thu, Nov 29, 2012 at 2:15 PM, Ivan Mincik
> <ivan.mincik at gmail.com <mailto:ivan.mincik at gmail.com>> wrote:
> 
> Hi, sure you know this - when editing/adding multiple features to
> layer and pressing 'save' button an error message appears because
> of some database constraint violation or invalid data type in
> attribute table. There is very hard to find out a problematic
> features when many of them where changed or added.
> 
> We wrote a small Python console script to print all dirty features
> with their attributes and WKT geometry:
> 
> # QGIS 1.7, 1.8, author: Marcel Dancak, Gista s.r.o. layer =
> qgis.utils.iface.activeLayer() map = qgis.utils.iface.mapCanvas() 
> layer.select(map.fullExtent(), False) fields =
> layer.dataProvider().fields() features = layer.selectedFeatures()
> 
> # filter only new features features = [f for f in features if f.id
> <http://f.id>() < 0] for f in features: attribs =
> dict([(unicode(fields[k].name().toUtf8()), 
> unicode(v.toString().toUtf8())) for k, v in 
> f.attributeMap().iteritems()]) print f.id <http://f.id>(), attribs,
> f.geometry().type(), f.geometry().exportToWkt()
> 
> 
> Are you interested just in newly added features or any "dirty"
> features, i.e. also changed features and removed features? Because
> the above would work just for new features. Currently it's not
> possible to access uncommitted changes... but in theory you could
> still iterate over vector layer and then iterate through its data
> provider and compare the results to detect all changes.
> 
> If you decide to create a plugin, you could listen to signals from 
> QgsVectorLayer (featureAdded, featureDeleted and others) to
> immediately detect any changes.
> 
> In general, any tools that would lead to easier detection of
> problems would be welcome.

Martin, thanks for Your comments. So we have two possibilities:
1. Check features for id < 0 and add changed features by comparing
current state to data provides which can be very expensive in case of
big layers.

2. To listen to signals of all existing layers in canvas which can be
very tricky in case of removing and adding layers.

Ivan

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