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Source code for xsdata.formats.dataclass.serializers.json

import json
import warnings
from dataclasses import dataclass
from dataclasses import field
from enum import Enum
from io import StringIO
from typing import Any
from typing import Callable
from typing import Dict
from typing import Iterator
from typing import Optional
from typing import TextIO
from typing import Tuple

from xsdata.formats.bindings import AbstractSerializer
from xsdata.formats.converter import converter
from xsdata.formats.dataclass.context import XmlContext
from xsdata.formats.dataclass.models.elements import XmlVar
from xsdata.formats.dataclass.serializers.config import SerializerConfig
from xsdata.utils import collections


def filter_none(x: Tuple) -> Dict:
    return {k: v for k, v in x if v is not None}


class DictFactory:
    """Dictionary factory types."""

    FILTER_NONE = filter_none


@dataclass
class JsonSerializer(AbstractSerializer):
    """
    Json serializer for dataclasses.

    :param config: Serializer configuration
    :param context: Model context provider
    :param dict_factory: Override default dict factory to add further logic
    :param dump_factory: Override default json.dump call with another implementation
    :param indent: Output indentation level
    """

    config: SerializerConfig = field(default_factory=SerializerConfig)
    context: XmlContext = field(default_factory=XmlContext)
    dict_factory: Callable = field(default=dict)
    dump_factory: Callable = field(default=json.dump)
    indent: Optional[int] = field(default=None)

    def render(self, obj: object) -> str:
        """Convert the given object tree to json string."""
        output = StringIO()
        self.write(output, obj)
        return output.getvalue()

    def write(self, out: TextIO, obj: Any):
        """
        Write the given object tree to the output text stream.

        :param out: The output stream
        :param obj: The input dataclass instance
        """

        indent: Optional[int] = None
        if self.indent:
            warnings.warn(
                "JsonSerializer indent property is deprecated, use SerializerConfig",
                DeprecationWarning,
            )
            indent = self.indent
        elif self.config.pretty_print:
            indent = 2

        self.dump_factory(self.convert(obj), out, indent=indent)

    def convert(self, obj: Any, var: Optional[XmlVar] = None) -> Any:
        if var is None or self.context.class_type.is_model(obj):

            if collections.is_array(obj):
                return [self.convert(o) for o in obj]

            return self.dict_factory(self.next_value(obj))

        if collections.is_array(obj):
            return type(obj)(self.convert(v, var) for v in obj)

        if isinstance(obj, (dict, int, float, str, bool)):
            return obj

        if isinstance(obj, Enum):
            return self.convert(obj.value, var)

        return converter.serialize(obj, format=var.format)

    def next_value(self, obj: Any) -> Iterator[Tuple[str, Any]]:
        ignore_optionals = self.config.ignore_default_attributes

        for var in self.context.build(obj.__class__).get_all_vars():
            value = getattr(obj, var.name)
            if var.is_attribute and ignore_optionals and var.is_optional(value):
                continue

            yield var.local_name, self.convert(value, var)