Maya: Get Attribute On Renderlayer

mgaor.py

import pymel.core

drg = pymel.core.PyNode('defaultRenderGlobals')

# iterate over the selected renderlayers.
# can select renderlayers through the outliner with "Display" > "DAG Objects Only"
data = {}
render_cams = []
for layer in pymel.core.ls(selection=True, type='renderLayer'):

    layer_data = {}
    render_cams = []
    if layer.adjustments.get(multiIndices=True):
        for count in layer.adjustments.get(multiIndices=True):
            if not layer.adjustments[count].plug.connections():
                continue

            if layer.adjustments[count].plug.connections()[0] == drg:
                attr = layer.adjustments[count].plug.connections(plugs=True)[0]
                layer_data[attr.name(includeNode=True)] = layer.adjustments[count].value.get()

            for cam_attr in layer.adjustments[count].plug.connections(plugs=True, type='camera'):
                if cam_attr.endswith('renderable') and layer.adjustments[count].value.get() == 1.0:
                    render_cams.append(pymel.core.PyNode(cam_attr.split('.')[0]).getParent())

        layer_data['renderpasses'] = layer.connections(type='renderPass')
    else:
        layer_data['renderpasses'] = layer.connections(type='renderPass')

    layer_data['cameras'] = render_cams
    data[layer.name()] = layer_data

print data