Quick example
import maya.OpenMaya as OpenMaya
m_obj = OpenMaya.MObject() # should get from any code above
m_dagPath = OpenMaya.MDagPath()
if m_obj.hasFn( OpenMaya.MFn.kDagNode ):
OpenMaya.MDagPath.getAPathTo( m_obj, m_dagPath )
print( m_dagPath.fullPathName() )