rin-jsonutils

rin-jsonutils is a toolkit that adds custom JSON coders and provides functions to set/get the default JSON coders

Links

• GitHub
• PyPI

Installation

pip install rin-jsonutils

Getting Started

Use the advanced encoder

This package default provides an advanced encoder

import json
import numpy as np
from datetime import datetime
from rin import jsonutils

jsonutils.use_advanced_coders()  # switch to advanced encoder
# jsonutils.use_basic_coders()  # switch back to original json coders 

assert json.dumps({1, 2, 3}) == '[1, 2, 3]'  # built-in set
assert json.dumps(np.arange(6).reshape((2, 3))) == '[[0, 1, 2], [3, 4, 5]]'  # numpy array

assert json.dumps(datetime.fromordinal(1)) == '"0001-01-01T00:00:00"' # datetime

Context of the advanced encoder

Context is a dict that stores encoder-specific options for resolvers. For example, setting the 'datetime.format' can affect the behavior when encoding datetime objects.

import json
from rin import jsonutils
from datetime import datetime

jsonutils.use_advanced_coders()
encoder: jsonutils.AdvancedJSONEncoder = jsonutils.get_current_coder().encoder

assert json.dumps(datetime.fromordinal(1)) == '"0001-01-01T00:00:00"' # default format is isoformat
# change the format of the datetime resolver in the encoder 
encoder.context['datetime.format'] = "%Y-%m-%d"
assert json.dumps(datetime.fromordinal(1)) == '"0001-01-01"'

Add custom resolver to the advanced encoder

You can write a custom resolver to encode something.

from typing import Dict, Any
from rin import jsonutils


class MyObject:
    def __init__(self, i: int):
        self.i = i


class MyObjectResolver(jsonutils.IResolver):
    def __init__(self, show_name: bool):
        self.show_name = show_name

    def get_priority(self) -> int:
        return jsonutils.ResolverPriority.MEDIUM

    def initialize(self) -> bool:
        """
        :return: False if initialization failed
        """
        return True

    def resolve(self, o, context: Dict[str, Any]) -> jsonutils.JSONType:
        """
        :raises ResolveError when cannot resolve the object.
                 If you aren't resolves the object, you MUST raise this exception.
        """
        show_name = context.get("my_object.show_name", self.show_name)
        if show_name:
            return {"name": "MyObject", "i": o.i}
        else:
            return {"i": o.i}


encoder = jsonutils.get_coder("advanced").encoder
encoder.add_resolver("my_object", MyObjectResolver(True))  # register the resolver to the encoder

assert encoder.encode(MyObject(1)) == '{"name": "MyObject", "i": 1}'
encoder.context['my_object.show_name'] = False  # change context
assert encoder.encode(MyObject(1)) == '{"i": 1}'

A simpler way to make object JSON serializable

You can write method __json__ for an object. Instead of create a resolver.

from typing import Dict, Any
from rin import jsonutils


class MyObject(jsonutils.JSONSerializable):  # inherit from JSONSerializable is optional.
    show_name: bool = True

    def __init__(self, i: int):
        self.i = i

    def __json__(self, context: Dict[str, Any]) -> jsonutils.JSONType:  # implement this method is required.
        show_name = context.get("my_object.show_name", self.show_name)
        if show_name:
            return {"name": "MyObject", "i": self.i}
        else:
            return {"i": self.i}

encoder = jsonutils.get_coder("advanced").encoder
assert encoder.encode(MyObject(1)) == '{"name": "MyObject", "i": 1}'
encoder.context['my_object.show_name'] = False
assert encoder.encode(MyObject(1)) == '{"i": 1}'

Register custom coders into code switch

import json
from rin import jsonutils


class MyJSONEncoder(json.JSONEncoder):
    ...


class MyJsonDecoder(json.JSONDecoder):
    ...


jsonutils.register_coder("my_coder", MyJSONEncoder(), MyJsonDecoder())
...
jsonutils.use("my_coder")