pyqgis_vector_summary.py

import itertools
import qgis
from qgis.gui import QgsMessageBar
from qgis.core import QgsMapLayer


def layer_info(layer):
    print "Layer name: %s" % layer.name()
    print "CRS: %s" % layer.crs().authid()
    print "Extent: %s" % layer.extent().asWktCoordinates()
    print "Feature count: %s" % layer.featureCount()
    print "Geometry type: %s" % qgis.core.QgsWKBTypes.displayString(int(layer.wkbType()))
    field_names = [field.name() for field in layer.fields().toList()]
    print "Fields: %s" % field_names

    num_features = min(2, layer.featureCount())
    print "First %d features..." % num_features

    features = itertools.islice(layer.getFeatures(), num_features)
    for feature in features:
        print "Feature ID %d: " % feature.id()
        print "Attributes: ", zip(field_names, feature.attributes())
        geom = feature.geometry().geometry()
        print "Geometry: ", geom.asJSON()


layer = qgis.utils.iface.activeLayer()
if layer and layer.type() == QgsMapLayer.VectorLayer:
    layer_info(layer)
else:
    qgis.utils.iface.messageBar().pushMessage("Please select a vector layer in the layer panel", QgsMessageBar.INFO, 4)