QGIS » QGIS Application

QgsFeatureRequest allows advanced features filtering via setFilterExpression() method. But seems this does not work, at least when using from Python.
Here is code snippet:

layer = iface.mapCanvas().currentLayer()
expr = '"dt" = \\'2014-07-05\\' AND abs("y" - 3.0) <= 0.000001'
request = QgsFeatureRequest().setFilterExpression(expr)
for f in layer.getFeatures(request):
  print 'found'

1. open attached shapefile and make it active
2. in Python console execute above code
3. no features found
4. now try to use same expression with "Select by Expression" tool, it finds one feature as expected.

See also this thread http://lists.osgeo.org/pipermail/qgis-developer/2014-July/033965.html