Question

I have the following simple methods for writing a python object to a file using jsonpickle:

def json_serialize(obj, filename, use_jsonpickle=True):
    f = open(filename, 'w')
    if use_jsonpickle:
        import jsonpickle
        json_obj = jsonpickle.encode(obj)
        f.write(json_obj)
    else:
        simplejson.dump(obj, f) 
    f.close()

def json_load_file(filename, use_jsonpickle=True):
    f = open(filename)
    if use_jsonpickle:
        import jsonpickle
        json_str = f.read()
        obj = jsonpickle.decode(json_str)
    else:
        obj = simplejson.load(f)
    return obj

the problem is that whenever I use these, it loads my objects back as dictionaries (that have fields like: “py/object”: “my_module.MyClassName”) but not as an actual Python object of the type that was used to generate the json string. How can I make it so jsonpickle actually converts the loaded string back to the object?

to illustrate this with an example, consider the following:

class Foo:
    def __init__(self, hello):
    self.hello = hello

# make a Foo obj
obj = Foo("hello world")
obj_str = jsonpickle.encode(obj)
restored_obj = jsonpickle.decode(obj_str)
list_objects = [restored_obj]
# We now get a list with a dictionary, rather than
# a list containing a Foo object
print "list_objects: ", list_objects

This yields:

list_objects:  [{'py/object': 'as_events.Foo', 'hello': 'hello world'}]

Rather than something like: [Foo()]. How can I fix this?

thanks.

Answer 1

The correct answer was that I was not inheriting from object. Without inheriting from object, jsonpickle cannot correctly decode classes that take one or more arguments in the constructor, it seems. I am by no means an expert but making it Foo(object): rather than Foo: in the class declaration fixed it.