Debug unpickled errors.

debug_pickle.py

# from http://stackoverflow.com/questions/569754/how-to-tell-for-which-object-attribute-pickle-fails

"""
Show which fields cannot be pickled
"""

import pickle
def get_pickling_errors(obj,seen=None):
    if seen is None:
        seen = []
    try:
        state = obj.__getstate__()
    except AttributeError:
        return
    if state is None:
        return
    if isinstance(state,tuple):
        if not isinstance(state[0],dict):
            state=state[1]
        else:
            state=state[0].update(state[1])
    result = {}    
    for i in state:
        try:
            pickle.dumps(state[i],protocol=2)
        except pickle.PicklingError:
            if not state[i] in seen:
                seen.append(state[i])
                result[i]=get_pickling_errors(state[i],seen)
    return result