ultimatepython/advanced/data_format.py

import json
from csv import DictReader
from dataclasses import dataclass, fields
from io import StringIO
from xml.etree import ElementTree as ETree

# Data in JSON format. For more info on this format:
# https://fileinfo.com/extension/json
_JSON_DATA = """
[
    {
        "author": "John",
        "title": "Summer",
        "body": "Summer time is hot"
    },
    {
        "author": "Jane",
        "title": "Winter",
        "body": "Winter time is cold"
    }
]
"""

# Data in XML format. For more info on this format:
# https://fileinfo.com/extension/xml
_XML_DATA = """
<notepad>
    <note>
        <author>John</author>
        <title>Summer</title>
        <body>Summer time is hot</body>
    </note>
    <note>
        <author>Jane</author>
        <title>Winter</title>
        <body>Winter time is cold</body>
    </note>
</notepad>
"""

# Data in CSV format. For more info on this format:
# https://fileinfo.com/extension/csv
_CSV_DATA = """
John,Summer,Summer time is hot
Jane,Winter,Winter time is cold
"""


@dataclass
class Note:
    """Note model."""
    author: str
    title: str
    body: str

    @classmethod
    def from_data(cls, data):
        """Create note from dictionary data."""
        return cls(**data)

    @classmethod
    def fields(cls):
        """Get field names to simplify parsing logic."""
        return tuple(field.name for field in fields(cls))


def main():
    # Let's use `json.load` to parse note data from a JSON file
    json_content = json.load(StringIO(_JSON_DATA))
    json_notes = [Note.from_data(data) for data in json_content]
    assert all(isinstance(note, Note) for note in json_notes)

    # Let's use `ElementTree.parse` to parse note data from a XML file
    tree = ETree.parse(StringIO(_XML_DATA))
    xml_notes = [
        Note.from_data({
            field: note_el.findtext(field)
            for field in Note.fields()
        }) for note_el in tree.getroot()
    ]
    assert all(isinstance(note, Note) for note in xml_notes)

    # Let's use `csv.DictReader` to parse note data from a CSV file
    csv_reader = DictReader(StringIO(_CSV_DATA), fieldnames=Note.fields())
    csv_notes = [Note.from_data(row) for row in csv_reader]
    assert all(isinstance(note, Note) for note in csv_notes)

    # All three formats have similar `Note` objects
    for json_note, xml_note, csv_note in zip(json_notes, xml_notes, csv_notes):
        assert json_note == xml_note == csv_note


if __name__ == "__main__":
    main()