schrodinger.models.json module

This is a module that extends Python’s standard builtin json module. It offers the following additional features:

exception schrodinger.models.json.JSONDecodeError

Bases: exceptions.ValueError

exception schrodinger.models.json.JSONEncodeError

Bases: exceptions.ValueError

class schrodinger.models.json.JSONEncoder(skipkeys=False, ensure_ascii=True, check_circular=True, allow_nan=True, sort_keys=False, indent=None, separators=None, encoding='utf-8', default=None)

Bases: json.encoder.JSONEncoder

A wrapper around the builtin JSON encoder that automatically encodes objects derived from JsonableClassMixin

default(obj)
class schrodinger.models.json.JsonableClassMixin(*args, **kwargs)

Bases: object

A mixin that aids in making a class Jsonable. Users must define _toJson(self) and _fromJson(cls, json_dict). For example:

class Person(JsonableClassMixin, object):

def __init__(self, full_name, age):
self.full_name = full_name self.age = age
def _toJson(self):
return {‘full_name’:self.full_name:
‘age’:self.age}

@classmethod def _fromJson(cls, json_dict):

return cls(json_dict[‘full_name’], json_dict[‘age’])

Now dump and dumps can encode Person:

# Encode to a file

abe = Person(‘Abraham Lincoln’, 208) with open(‘abe.json’, ‘w’) as out_file:

json.dump(abe, out_file)

# Encode to a string abe_json_string = json.dumps(abe)

If you want to decode the json string or file, you’ll have to use loads or load and then feed in the result to your class’ public class method fromJson():

# Loading an object from a json file
with open(‘abe.json’, ‘r’) as in_file:
abe_json = json.load(in_file) abe = Person.fromJson(abe_json)

# Loading an object from a json string abe_json = json.loads(abe_json_string) abe = Person.fromJson(abe_json)

classmethod fromJson(json_dict)

A factory method which constructs a new object from a given dict loaded from a json string or file.

Parameters:
  • json_dict (dict) – A json-loaded dictionary to create an object from.
  • copy_dict (bool) – Whether to copy the dict before modifying it. If set to False, the dict won’t be safe to use in another fromJson() call. Defaults to False.
Returns:

An instance of this class.

:rtype : cls

Raises:JsonDecodeError – If the json dict is corrupted or invalid.
get_version()

Method to get the version of a particular object. Defaults to the current version of mmshare. This class can be overridden for custom versioning behavior.

toJson()

Create and returns a data structure made up of jsonable items.

schrodinger.models.json.adapter(version)

This function is a decorator used to define an adapter function that takes in a json_dict from an older version of a JsonableClassMixin and returns it modified such that it can be read in by the version of the class specified by the version argument (typically the current version at the time the adapter is written).

As a example, imagine we define a simple class:

class Person:

# mmshare version: 40000 def __init__(self, full_name):

self.full_name = full_name

If, in mmshare version 41000, we split full_name into attributes first_name and last_name, we could define an adapter like so:

class Person:

# mmshare version: 41000 def __init__(self, first_name, last_name):

self.first_name = first_name self.last_name = last_name

@json.adapter(version=41000) def _JsonAdapter(self, json_dict):

full_name = json_dict.pop(full_name) fname, lname = full_name.split(‘ ‘) json_dict[‘first_name’] = fname json_dict[‘last_name’] = lname return json_dict

An adapter function only needs to bring the json_dict up-to-date with the class at the time that the adapter is written. The next time the class is changed in a way that breaks json decoding, a new adapter function should be added to the class that takes in the previous adapter’s output and makes it compatible with the current class. In this way the json framework can decode any older version by automatically passing it through the appropriate chain of adapter functions.

Parameters:version (int, str, or list of str or ints) – The data version to which an older json_dict will be adapted (typically the current version when the adapter is writte).
Raises:TypeError – if version is not an int, str, or list
schrodinger.models.json.dump(fp, **kwargs)

A wrapper that uses an encoder to automatically encode objects derived from JsonableClassMixin.

schrodinger.models.json.dumps(obj, **kwargs)

A wrapper that uses an encoder to automatically encode objects derived from JsonableClassMixin.