example.py

def getRecords(kw=None):
    """
    @param kw: A dictionary of narrowing criteria for the records.  For example,
        if you wanted to only show records for student's named "Bill" you would
        pass::
            
            {'first': 'Bill'}
    """
    if not kw:
        kw = {}
    
    records = store.find((Student, Class, Grade),
                          Student.id == Grade.student_id,
                          Grade.class_id == Class.id)
    
    if 'student_id' in kw:
        records = records.find(Student.id == unicode(kw['student_id']))
    
    if 'class_id' in kw:
        records = records.find(Class.id == int(kw['class_id']))
    
    if 'first' in kw:
        records = records.find(Student.first == unicode(kw['first']))
    
    #...
    
    return records