python/pyiceberg/serializers.py

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import codecs
import json
from typing import Union

from pyiceberg.io.base import InputFile, InputStream, OutputFile
from pyiceberg.table.metadata import TableMetadata, TableMetadataV1, TableMetadataV2


class FromByteStream:
    """A collection of methods that deserialize dictionaries into Iceberg objects"""

    @staticmethod
    def table_metadata(byte_stream: InputStream, encoding: str = "utf-8") -> TableMetadata:
        """Instantiate a TableMetadata object from a byte stream

        Args:
            byte_stream: A file-like byte stream object
            encoding (default "utf-8"): The byte encoder to use for the reader
        """
        reader = codecs.getreader(encoding)
        metadata = json.load(reader(byte_stream))  # type: ignore
        return TableMetadata.parse_obj(metadata)  # type: ignore


class FromInputFile:
    """A collection of methods that deserialize InputFiles into Iceberg objects"""

    @staticmethod
    def table_metadata(input_file: InputFile, encoding: str = "utf-8") -> TableMetadata:
        """Create a TableMetadata instance from an input file

        Args:
            input_file (InputFile): A custom implementation of the iceberg.io.file.InputFile abstract base class
            encoding (str): Encoding to use when loading bytestream

        Returns:
            TableMetadata: A table metadata instance

        """
        return FromByteStream.table_metadata(byte_stream=input_file.open(), encoding=encoding)


class ToOutputFile:
    """A collection of methods that serialize Iceberg objects into files given an OutputFile instance"""

    @staticmethod
    def table_metadata(
        metadata: Union[TableMetadataV1, TableMetadataV2], output_file: OutputFile, overwrite: bool = False
    ) -> None:
        """Write a TableMetadata instance to an output file

        Args:
            output_file (OutputFile): A custom implementation of the iceberg.io.file.OutputFile abstract base class
            overwrite (bool): Where to overwrite the file if it already exists. Defaults to `False`.
        """
        f = output_file.create(overwrite=overwrite)
        f.write(metadata.json().encode("utf-8"))
        f.close()