[Qgis-developer] Python access to ogr provider datasource layer name

[godofredo contreras]

Hi Dane:

Sublayers returns a QStringList with one string per layer, the string has four components separated by a ":", the components are:

LayerIndex : LayerName : FeatureCount : GeometryType

Regards

Godofredo Contreras


> From: blake at hailmail.net
> To: qgis-developer at lists.osgeo.org
> Date: Tue, 2 Jun 2009 17:54:04 -0700
> Subject: [Qgis-developer] Python access to ogr provider datasource layer name
> 
> So OGR has this notion of data files and then their layers. I'm trying  
> to figure out in QGIS how to get at this information via python for  
> data loaded into QGIS.
> 
> For example, for this sample gml file: http://svn.osgeo.org/gdal/trunk/autotest/ogr/data/ionic_wfs.gml
> 
> ogrinfo -so -al gives:
> 
> Had to open data source read-only.
> INFO: Open of `/Users/spring/src/gdal/autotest/ogr/data/ionic_wfs.gml'
>        using driver `GML' successful.
> 
> Layer name: GEM
> Geometry: Unknown (any)
> Feature Count: 1
> Extent: (437.000000, 51131.000000) - (44137.000000, 511549.000000)
> Layer SRS WKT:
> (unknown)
> Name: String (0.0)
> 
> What I am looking for is access to the name 'GEM'.
> 
> Via python I notice that 'subLayers()' are empty:
> 
>  >>> l = iface.mapCanvas().layer(0)
>  >>> l.subLayers()
> <PyQt4.QtCore.QStringList object at 0x13101618>
>  >>> l.subLayers()[0]
> exceptions.IndexError: sequence index out of range
> 
> While the provider subLayers have the name embedded in an odd Qstring:
>  >>> l.dataProvider().subLayers()[0]
> 0:GEM:0:Unknown
> 
> Is parsing this string they best way to get at this information? What  
> happens in QGIS when there are multiple layers?
> 
> Running this on a shapefile and a GeoJSON file I get this:
> 
>  >>> l.dataProvider().subLayers()[0]
> 0:statesp020:2895:Polygon
> 
> http://svn.osgeo.org/gdal/trunk/autotest/ogr/data/multipolygon.geojson
>  >>> l.dataProvider().subLayers()[0]
> 0:OGRGeoJSON:1:Unknown WKB: 6
> 
> Can anyone explain what those numbers mean - Number of features?
> 
> Thanks,
> 
> Dane
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