Pickleing

[sirdeltalot]

Hi
I'm a total beginner in python.
Want i want to know is how to pickle a dictionary after a user has updated it then read back from the pickled file.
Thanks
Iz

[bvdet]

I used to use the following functions for saving and recalling a dictionary or list of dictionaries to a file using pickle.

import pickle
 
def import_data(file_name):
    try:
        f = open(file_name, "r")
    except IOError, e:
        # unable to open file
        Warning("Default file import error. Reverting to original defaults...")
        return None
 
    # file open is successful
    try:
 
        dd = pickle.Unpickler(f).load()
        f.close()
        # test for a dictionary or list of dictionaries
        if isinstance(dd, dict):
            return dd
        elif isinstance(dd, list):
            for i, item in enumerate(dd):
                if not isinstance(item, dict):
                    Warning("**INVALID** List item %s is not a dictionary." % (i))
                    return None
            # always return one dictionary
            ddr = {}
            for d in dd: ddr.update(d)
            return ddr
        else:
            # dd is not a dictionary or list of dictionaries
            Warning("Invalid imported data type.\nData must be a dictionary or list of dictionaries.")
            return None
 
    except:
        # file is not compatible with Unpickler - close file and warn user
        f.close()
        Warning("Invalid defaults file. Reverting to original defaults...")
        return None
 
def export_data(file_name, dd):
    if check_Defaults_dir(os.path.dirname(file_name)):
        # directory exists or was created
        try:
            f = open(file_name, "w")
            pickle.Pickler(f).dump(dd)
            f.close()
            return True
        except:
            Warning("Default values file export error.")
            return False
 
    else:
        # directory did not exist and the user chose 'no' to create directory
        Warning("The default values file export was aborted")
        return False

[sirdeltalot]

That's realy helpful,
Thanks!