Python to get ids from shapefile don't return all records

Question

I have some Python code to get the ids and georeference from a shapefile:

canvas = qgis.utils.iface.mapCanvas()
allLayers = canvas.layers()
nos = QgsFeature()
for i in allLayers:
    if i.name()=='path_nodes':
        path_nodes = i

nodedata  = path_nodes.dataProvider()

while nodedata.nextFeature(nos):
    i = i + 1
    print str(no.gid())

It does not return all of the ids. Can anyone help?

Answer 1

In the while loop, no doesn't refer to anything, you need to assign it to the current feature. I don't know how the QGIS API works, so here's a somewhat ugly approach:

while True:
    try:
        no = nodedata.nextFeature(nos)
    except:
        break
    print str(no.gid())

Answer 2

As @bananafish noted, no should be nos. You might also want to set i=0 before the loop.

nos = QgsFeature()
while nodedata.nextFeature(nos):
    i = i + 1
    print str(nos.gid())