Method to serialize custom object to JSON in Python
json, python
Solution
If you only need Python -> JSON, it's simple to write a JSONEncoder class that calls such a method for any object:
class AutoJSONEncoder(JSONEncoder):
def default(self, obj):
try:
return obj._json()
except AttributeError:
return JSONEncoder.default(self, obj)
You can then use the class directly `AutoJSONEncoder().encode(obj)` or through the `dumps` interface `json.dumps(obj, cls=AutoJSONEncoder)`.
The reverse direction requires at least a list of classes for which to call a `_fromjson` method.
(Note: `__foo__` names are reserved so you shouldn't define them for your own purposes. `__bar` invokes name mangling, which probably isn't what you want.)
Problem
Generally, we can define `__str__` method to make `str(obj)` return what we want. But now I want to define my Model object to return a default JSON string when using `json.dumps(obj)`. Is there any nice way for me to declare a method in the class to do this? ``` class MyClass: ... def __json__(self): return {'name': self.name, 'age': self.age} obj = MyClass() json.dumps(obj) # returns the same as json.dumps(obj.__json__) ```