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A Python library for converting dataclasses from and to JSON
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tushkanin/jsondataclass
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README.rst
jsondataclass is a library that makes it easy for you to convert of dataclasses (PEP 557) to and from JSON.
pip3 install jsondataclass
from dataclasses import dataclass from jsondataclass import to_json, from_json @dataclass class Movie: name: str year: int county: str movie = Movie("Terminator: Dark Fate", 2019, "USA") print(to_json(movie)) # json_str = '' print(from_json(json_str, Movie)) # Movie(name='Terminator: Dark Fate', year=2019, county='USA')
- str, int, bool, dict, list, tuple
- nested dataclasses
- typing.List
- typing.Tuple
- typing.Dict
- typing.Optional
- typing.Union
- typing.Literal (python >= 3.8 required)
- datetime.datetime
- datetime.date
- datetime.time
- timestamp
- Enum
- Decimal
The primary functions to use are from_json and to_json . There is also a class DataClassMapper with methods from_json and to_json available that can be used to configure conversion operations.
The DataClassMapper instance does not maintain any state while invoking Json operations. So, you are free to reuse the same object for multiple Json serialization and deserialization operations.
from dataclasses import dataclass from jsondataclass import to_json, DataClassMapper @dataclass class User: id: int name: str user = User(1, "John Doe") mapper = DataClassMapper() json_str = mapper.to_json(user) print(json_str) # # or json_str = to_json(user) print(json_str) #
from dataclasses import dataclass from jsondataclass import from_json, DataClassMapper @dataclass class User: id: int name: str json_str = '' mapper = DataClassMapper() user = mapper.from_json(json_str, User) print(user) # User(id=1, name='John Doe') # or user = from_json(json_str, User) print(user) # User(id=1, name='John Doe')
from dataclasses import dataclass from jsondataclass import to_dict, DataClassMapper @dataclass class User: id: int name: str user = User(1, "John Doe") mapper = DataClassMapper() dict_obj = mapper.to_dict(user) print(dict_obj) # # or dict_obj = to_dict(user) print(dict_obj) #
from dataclasses import dataclass from jsondataclass import to_dict, DataClassMapper @dataclass class User: id: int name: str user = User(1, "John Doe") mapper = DataClassMapper() dict_obj = mapper.to_dict(user) print(dict_obj) # # or dict_obj = to_dict(user) print(dict_obj) #
from dataclasses import dataclass from jsondataclass import from_json, to_json @dataclass class ContactInfo: email: str phone_number: str @dataclass class User: id: int name: str info: ContactInfo user = User(1, "John Doe", ContactInfo("john@doe.com", "+19999999")) print(to_json(user)) # > json_str = '>' print(from_json(json_str, User)) # User(id=1, name='John Doe', info=ContactInfo(email='john@doe.com', phone_number='+19999999'))
from dataclasses import dataclass from jsondataclass import from_json, to_json, jsonfield @dataclass class User: id: int = jsonfield("Id") name: str = jsonfield("Name") json_str = '' user = from_json(json_str, User) print(user) # User(id=1, name='John Doe') json_str = to_json(user) print(json_str) #
from dataclasses import dataclass from typing import Optional from jsondataclass import from_json @dataclass class User: id: int name: str email: Optional[str] json_str = '' user = from_json(json_str, User) print(user) # User(id=1, name='John Doe', email=None)
from dataclasses import dataclass from typing import Union from jsondataclass import from_json, to_json @dataclass class User: id: Union[int, str] name: str json_str = '' user = from_json(json_str, User) print(user) # User(id=1, name='John Doe') json_str = to_json(user) print(json_str) #
from dataclasses import dataclass from typing import List, Tuple, Dict from jsondataclass import from_json, to_json @dataclass class Movie: genres: List[str] rating: Tuple[float, int] name: Dict[str, str] movie = Movie(["comedy", "crime"], (5.6, 100), "en": "WALL-E", "de": "WALL-E">) json_str = to_json(movie) print(json_str) # > json_str = '>' movie = from_json(json_str, Movie) print(movie) # Movie(genres=['comedy', 'crime'], rating=(5.6, 100), name=)
from dataclasses import dataclass from typing import Literal from jsondataclass import from_json, to_json @dataclass class Movie: name: str year: int rating: Literal[1, 2, 3, 4, 5] movie = Movie("Terminator: Dark Fate", 2019, 5) print(to_json(movie)) # > json_str = '' print(from_json(json_str, Movie)) # > Movie(name='Terminator: Dark Fate', year=2019, rating=5)
from dataclasses import dataclass from enum import Enum from jsondataclass import from_json, to_json class Role(Enum): ADMIN = 1 STAFF = 2 GUEST = 3 @dataclass class User: id: int name: str role: Role user = User(1, "John Doe", Role.ADMIN) json_str = to_json(user) print(json_str) # json_str = '' user = from_json(json_str, User) print(user) # User(id=1, name='John Doe', role=)
Decimal type can be decerialized from integer, float or string, but is serialized always to string.
from dataclasses import dataclass from decimal import Decimal from jsondataclass import from_json, to_json @dataclass class User: id: int name: str salary: Decimal user = User(1, "John Doe", Decimal("11.22")) json_str = to_json(user) print(json_str) # json_str = '' user = from_json(json_str, User) print(user) # User(id=1, name='John Doe', salary=Decimal('11.22'))
Serialization of datetime , date and time objects are performed using isoformat(), and fromisoformat() are used for deserialization.
from dataclasses import dataclass from datetime import datetime, date, time from jsondataclass import from_json, to_json, DataClassMapper, jsonfield @dataclass class User: id: int name: str last_login: datetime birthday: date local_time: time user = User(1, "John Doe", datetime.now(), date(2000, 1, 1), time(0, 0, 0, 0)) json_str = to_json(user) print(json_str) # user = from_json(json_str, User) print(user) # User(id=1, name='John Doe', last_login=datetime.datetime(2019, 10, 31, 18, 54, 35, 688288), birthday=datetime.date(2000, 1, 1), local_time=datetime.time(0, 0))
But you can specify format via DataClassMapper instance.
mapper = DataClassMapper() mapper.datetime_format = "%m/%d/%y %H:%M:%S" mapper.date_format = "%m/%d/%y" mapper.time_format = "%H:%M" user = User(1, "John Doe", datetime.now(), date(2000, 1, 1), time(0, 0, 0, 0)) json_str = mapper.to_json(user) print(json_str) # user = mapper.from_json(json_str, User) print(user) # User(id=1, name='John Doe', last_login=datetime.datetime(2019, 10, 31, 18, 59, 11), birthday=datetime.date(2000, 1, 1), local_time=datetime.time(0, 0))
Or via jsonfield function.
@dataclass class User: id: int name: str last_login: datetime = jsonfield(serializer_args=("%y/%m/%d %H:%M:%S",)) birthday: date = jsonfield(serializer_args=("%y/%m/%d",)) local_time: time = jsonfield(serializer_args=("%I:%M %p",)) user = User(1, "John Doe", datetime.now(), date(2000, 1, 1), time(0, 0, 0, 0)) json_str = to_json(user) print(json_str) # user = from_json(json_str, User) print(user) # User(id=1, name='John Doe', last_login=datetime.datetime(2019, 10, 31, 19, 0, 58), birthday=datetime.date(2000, 1, 1), local_time=datetime.time(0, 0))
By default, deserialization of timestamp result datetime naive object.
from dataclasses import dataclass from datetime import datetime, timezone from jsondataclass import from_json, to_json, jsonfield @dataclass class User: id: int name: str last_login: datetime.timestamp user = User(1, "John Doe", datetime.now()) json_str = to_json(user) print(json_str) # user = from_json(json_str, User) print(user) # User(id=1, name='John Doe', last_login=datetime.datetime(2019, 10, 31, 19, 7, 41))
You can specify timezone using jsonfield function.
@dataclass class User: id: int name: str last_login: datetime.timestamp = jsonfield(serializer_kwargs="timezone": timezone.utc>) user = User(1, "John Doe", datetime.now()) json_str = to_json(user) print(json_str) # user = from_json(json_str, User) print(user) # User(id=1, name='John Doe', last_login=datetime.datetime(2019, 10, 31, 17, 12, 36, tzinfo=datetime.timezone.utc))
from dataclasses import dataclass from jsondataclass import from_json, to_json from jsondataclass.utils import set_forward_refs @dataclass class User: id: int name: str info: "ContactInfo" @dataclass class ContactInfo: email: str phone_number: str set_forward_refs(User, "ContactInfo": ContactInfo>) user = User(1, "John Doe", ContactInfo("john@doe.com", "+19999999")) print(to_json(user)) # > json_str = '>' print(from_json(json_str, User)) # User(id=1, name='John Doe', info=ContactInfo(email='john@doe.com', phone_number='+19999999'))
Custom Serialization and Deserialization
Sometimes default representation is not what you want. DataClassMapper allows you to register your own custom serializers.
from dataclasses import dataclass from typing import Type from jsondataclass import DataClassMapper, jsonfield, to_json, from_json from jsondataclass.serializers import Serializer class Rating: def __init__(self, rating, vote_count): self.rating = rating self.vote_count = vote_count def __repr__(self): return f"Rating(rating=self.rating>, vote_count=self.vote_count>)" class RatingSerializer(Serializer[list]): def serialize(self, data: Rating) -> list: return [data.rating, data.vote_count] def deserialize(self, data: list, type_: Type[Rating]) -> Rating: return Rating(*data) @dataclass class Movie: name: str year: int rating: Rating movie = Movie("Terminator: Dark Fate", 2019, Rating(5, 100)) mapper = DataClassMapper() mapper.register_serializer(Rating, RatingSerializer) json_str = mapper.to_json(movie) print(json_str) # json_str = '' movie = mapper.from_json(json_str, Movie) print(movie) # Movie(name='Terminator: Dark Fate', year=2019, rating=Rating(rating=5, vote_count=100))
Or you can set your serializer on per-field level.
@dataclass class Movie: name: str year: int rating: Rating = jsonfield(serializer_class=RatingSerializer) movie = Movie("Terminator: Dark Fate", 2019, Rating(5, 100)) json_str = to_json(movie) print(json_str) # json_str = '' movie = from_json(json_str, Movie) print(movie) # Movie(name='Terminator: Dark Fate', year=2019, rating=Rating(rating=5, vote_count=100))
Also, you can override builtin serializers.
class UpperStringSerializer(Serializer[str]): def serialize(self, data: str) -> str: return data.upper() def deserialize(self, data: str, type_: Type[str]) -> str: return data.upper() @dataclass class Movie: name: str year: int movie = Movie("Terminator: Dark Fate", 2019) mapper = DataClassMapper() mapper.register_serializer(str, UpperStringSerializer) json_str = mapper.to_json(movie) print(json_str) # json_str = '' movie = mapper.from_json(json_str, Movie) print(movie) # Movie(name='TERMINATOR: DARK FATE', year=2019) @dataclass class Movie: name: str = jsonfield(serializer_class=UpperStringSerializer) year: int movie = Movie("Terminator: Dark Fate", 2019) json_str = mapper.to_json(movie) print(json_str) # json_str = '' movie = mapper.from_json(json_str, Movie) print(movie) # Movie(name='TERMINATOR: DARK FATE', year=2019)
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A Python library for converting dataclasses from and to JSON