nizika_nico/update_db.py

"""
日次で実行し，ぼざクリ DB を最新に更新する．
"""

from __future__ import annotations

import json
import os
import random
import string
import time
from dataclasses import dataclass
from datetime import datetime, timedelta
from typing import Any, TypedDict, cast

import mysql.connector
import requests

# TODO: “何もしなぃ” を意味する None と区別可能にするため，NULL クラスを別途用意すること
DbNull = None
DbNullType = type (None)


class VideoSearchParam (TypedDict):
    q:          str
    targets:    str
    _sort:      str
    fields:     str
    _limit:     int
    jsonFilter: str


class VideoResult (TypedDict):
    contentId:      str
    title:          str
    tags:           str
    description:    str
    viewCounter:    int
    startTime:      str


class CommentResult (TypedDict):
    id:             str
    no:             int
    vposMs:         int
    body:           str
    commands:       list[str]
    userId:         str
    isPremium:      bool
    score:          int
    postedAt:       str
    nicoruCount:    int
    nicoruId:       Any
    source:         str
    isMyPost:       bool


def main (
) -> None:
    conn = mysql.connector.connect (user        = os.environ['MYSQL_USER'],
                                    password    = os.environ['MYSQL_PASS'],
                                    database    = 'nizika_nico')

    now = datetime.now ()

    video_dao = VideoDao (conn)
    tag_dao = TagDao (conn)
    video_tag_dao = VideoTagDao (conn)
    video_history_dao = VideoHistoryDao (conn)
    comment_dao = CommentDao (conn)
    user_dao = UserDao (conn)

    api_data = search_nico_by_tags (['伊地知ニジカ', 'ぼざろクリーチャーシリーズ'])

    update_tables (video_dao, tag_dao, video_tag_dao, video_history_dao, comment_dao, user_dao,
                   api_data, now)

    conn.commit ()
    conn.close ()


def update_tables (
        video_dao:          VideoDao,
        tag_dao:            TagDao,
        video_tag_dao:      VideoTagDao,
        video_history_dao:  VideoHistoryDao,
        comment_dao:        CommentDao,
        user_dao:           UserDao,
        api_data:           list[VideoResult],
        now:                datetime,
) -> None:
    video_ids: list[int] = []
    for datum in api_data:
        tag_names = datum['tags'].split ()
        video = VideoDto (code          = datum['contentId'],
                          title         = datum['title'],
                          description   = datum['description'],
                          uploaded_at   = datetime.fromisoformat (datum['startTime']))
        video_dao.upsert (video, False)
        if video.id_ is not None:
            video_ids.append (video.id_)
            video_history = VideoHistoryDto (video_id       = video.id_,
                                             fetched_at     = now,
                                             views_count    = datum['viewCounter'])
            video_history_dao.insert (video_history)
            tag_ids: list[int] = []
            video_tags = video_tag_dao.fetch_alive_by_video_id (video.id_, False)
            for vt in video_tags:
                tag = tag_dao.find (vt.tag_id)
                if (tag is not None
                        and (tag.name not in tag_names)
                        and (tag.id_ is not None)):
                    tag_ids.append (tag.id_)
            video_tag_dao.untag_all (video.id_, tag_ids, now)
        tags: list[TagDto] = []
        for tag_name in tag_names:
            tag = tag_dao.fetch_by_name (tag_name)
            if tag is None:
                tag = TagDto (name = tag_name)
                tag_dao.insert (tag)
            if video.id_ is not None and tag.id_ is not None:
                video_tag = video_tag_dao.fetch_alive_by_ids (video.id_, tag.id_, False)
                if video_tag is None:
                    video_tag = VideoTagDto (video_id  = video.id_,
                                             tag_id    = tag.id_,
                                             tagged_at = now)
                    video_tag_dao.insert (video_tag, False)
        for com in fetch_comments (video.code):
            user = user_dao.fetch_by_code (com['userId'])
            if user is None:
                user = UserDto (code = com['userId'])
                user_dao.insert (user)
            if video.id_ is not None and user.id_ is not None:
                comment = CommentDto (video_id      = video.id_,
                                      comment_no    = com['no'],
                                      user_id       = user.id_,
                                      content       = com['body'],
                                      posted_at     = datetime.fromisoformat (com['postedAt']),
                                      nico_count    = com['nicoruCount'],
                                      vpos_ms       = com['vposMs'])
                comment_dao.upsert (comment, False)

    alive_video_codes = [d['contentId'] for d in api_data]

    lost_video_ids: list[int] = []
    videos = video_dao.fetch_alive ()
    for video in videos:
        if video.id_ is not None and video.code not in alive_video_codes:
            lost_video_ids.append (video.id_)

    video_dao.delete (lost_video_ids, now)


def fetch_comments (
        video_code: str,
) -> list[CommentResult]:
    time.sleep (1.2)

    headers = { 'X-Frontend-Id':      '6',
                'X-Frontend-Version': '0' }

    action_track_id = (
            ''.join (random.choice (string.ascii_letters + string.digits)
                     for _ in range (10))
            + '_'
            + str (random.randrange (10 ** 12, 10 ** 13)))

    url = (f"https://www.nicovideo.jp/api/watch/v3_guest/{ video_code }"
            + f"?actionTrackId={ action_track_id }")

    res = requests.post (url, headers = headers, timeout = 60).json ()

    try:
        nv_comment = res['data']['comment']['nvComment']
    except KeyError:
        return []
    if nv_comment is None:
        return []

    headers = { 'X-Frontend-Id':        '6',
                'X-Frontend-Version':   '0',
                'Content-Type':         'application/json' }

    params = { 'params':        nv_comment['params'],
               'additionals':   { },
               'threadKey':     nv_comment['threadKey'] }

    url = nv_comment['server'] + '/v1/threads'

    res = (requests.post (url, json.dumps (params),
                          headers = headers,
                          timeout = 60)
            .json ())

    try:
        return res['data']['threads'][1]['comments']
    except (IndexError, KeyError):
        return []


def search_nico_by_tag (
        tag:    str,
) -> list[VideoResult]:
    return search_nico_by_tags ([tag])


def search_nico_by_tags (
        tags:   list[str],
) -> list[VideoResult]:
    today = datetime.now ()

    url = ('https://snapshot.search.nicovideo.jp'
            + '/api/v2/snapshot/video/contents/search')

    result_data: list[VideoResult] = []
    to = datetime (2022, 12, 3)
    while to <= today:
        time.sleep (1.2)
        until = to + timedelta (days = 14)
        query_filter = json.dumps ({ 'type':    'or',
                                     'filters': [
                { 'type':          'range',
                  'field':         'startTime',
                  'from':          '%04d-%02d-%02dT00:00:00+09:00' % (to.year, to.month, to.day),
                  'to':            '%04d-%02d-%02dT23:59:59+09:00' % (until.year, until.month, until.day),
                  'include_lower': True }] })
        params: VideoSearchParam = { 'q':          ' OR '.join (tags),
                                     'targets':    'tagsExact',
                                     '_sort':      '-viewCounter',
                                     'fields':     ('contentId,'
                                                    'title,'
                                                    'tags,'
                                                    'description,'
                                                    'viewCounter,'
                                                    'startTime'),
                                     '_limit':     100,
                                     'jsonFilter': query_filter }
        res = requests.get (url, params = cast (dict[str, int | str], params), timeout = 60).json ()
        try:
            result_data += res['data']
        except KeyError:
            pass
        to = until + timedelta (days = 1)

    return result_data


class VideoDao:
    def __init__ (
            self,
            conn
    ):
        self.conn = conn

    def find (
            self,
            video_id:               int,
            with_relation_tables:   bool,
    ) -> VideoDto | None:
        with self.conn.cursor (dictionary = True) as c:
            c.execute ("""
                    SELECT
                      id,
                      code,
                      title,
                      description,
                      uploaded_at,
                      deleted_at
                    FROM
                      videos
                    WHERE
                      id = %s
                    ORDER BY
                      id""", (video_id,))
            row = c.fetchone ()
            if row is None:
                return None
            return self._create_dto_from_row (row, with_relation_tables)

    def fetch_all (
            self,
            with_relation_tables: bool,
    ) -> list[VideoDto]:
        with self.conn.cursor (dictionary = True) as c:
            c.execute ("""
                    SELECT
                      id,
                      code,
                      title,
                      description,
                      uploaded_at,
                      deleted_at
                    FROM
                      videos
                    ORDER BY
                      id""")
            videos: list[VideoDto] = []
            for row in c.fetchall ():
                videos.append (self._create_dto_from_row (row, with_relation_tables))
            return videos

    def fetch_alive (
            self,
    ) -> list[VideoDto]:
        with self.conn.cursor (dictionary = True) as c:
            c.execute ("""
                    SELECT
                      id,
                      code,
                      title,
                      description,
                      uploaded_at,
                      deleted_at
                    FROM
                      videos
                    WHERE
                      deleted_at IS NULL""")
            videos: list[VideoDto] = []
            for row in c.fetchall ():
                videos.append (self._create_dto_from_row (row, False))
            return videos

    def upsert (
            self,
            video:                  VideoDto,
            with_relation_tables:   bool,
    ) -> None:
        with self.conn.cursor (dictionary = True) as c:
            c.execute ("""
                    INSERT INTO
                      videos(
                        code,
                        title,
                        description,
                        uploaded_at,
                        deleted_at)
                    VALUES
                      (
                        %s,
                        %s,
                        %s,
                        %s,
                        %s)
                    ON DUPLICATE KEY UPDATE
                      code = VALUES(code),
                      title = VALUES(title),
                      description = VALUES(description),
                      uploaded_at = VALUES(uploaded_at),
                      deleted_at = VALUES(deleted_at)""", (video.code,
                                                           video.title,
                                                           video.description,
                                                           video.uploaded_at,
                                                           video.deleted_at))
            video.id_ = c.lastrowid
            if with_relation_tables:
                if video.video_tags is not None:
                    VideoTagDao (self.conn).upsert_all (video.video_tags, False)
                if video.comments is not None:
                    CommentDao (self.conn).upsert_all (video.comments, False)
                if video.video_histories is not None:
                    VideoHistoryDao (self.conn).upsert_all (video.video_histories)

    def upsert_all (
            self,
            videos:                 list[VideoDto],
            with_relation_tables:   bool,
    ) -> None:
        for video in videos:
            self.upsert (video, with_relation_tables)

    def delete (
            self,
            video_ids:  list[int],
            at:         datetime,
    ) -> None:
        if not video_ids:
            return
        with self.conn.cursor (dictionary = True) as c:
            c.execute ("""
                    UPDATE
                      videos
                    SET
                      deleted_at = %%s
                    WHERE
                      id IN (%s)""" % ', '.join (['%s'] * len (video_ids)), (at, *video_ids))

    def _create_dto_from_row (
            self,
            row,
            with_relation_tables:   bool,
    ) -> VideoDto:
        video = VideoDto (id_             = row['id'],
                          code            = row['code'],
                          title           = row['title'],
                          description     = row['description'],
                          uploaded_at     = row['uploaded_at'],
                          deleted_at      = row['deleted_at'])
        if with_relation_tables and video.id_ is not None:
            video.video_tags = VideoTagDao (self.conn).fetch_by_video_id (video.id_, False)
            for i in range (len (video.video_tags)):
                video.video_tags[i].video = video
            video.comments = CommentDao (self.conn).fetch_by_video_id (video.id_, False)
            for i in range (len (video.comments)):
                video.comments[i].video = video
            video.video_histories = VideoHistoryDao (self.conn).fetch_by_video_id (video.id_, False)
            for i in range (len (video.video_histories)):
                video.video_histories[i].video = video
        return video


@dataclass (slots = True)
class VideoDto:
    code:               str
    title:              str
    description:        str
    uploaded_at:        datetime
    id_:                int | None                      = None
    deleted_at:         datetime | DbNullType           = DbNull
    video_tags:         list[VideoTagDto] | None        = None
    comments:           list[CommentDto] | None         = None
    video_histories:    list[VideoHistoryDto] | None    = None


class VideoTagDao:
    def __init__ (
            self,
            conn,
    ):
        self.conn = conn

    def fetch_by_video_id (
            self,
            video_id:               int,
            with_relation_tables:   bool,
    ) -> list[VideoTagDto]:
        with self.conn.cursor (dictionary = True) as c:
            c.execute ("""
                    SELECT
                      id,
                      video_id,
                      tag_id,
                      tagged_at,
                      untagged_at
                    FROM
                      video_tags
                    WHERE
                      video_id = %s
                    ORDER BY
                      id""", (video_id,))
            video_tags: list[VideoTagDto] = []
            for row in c.fetchall ():
                video_tags.append (self._create_dto_from_row (row, with_relation_tables))
            return video_tags

    def fetch_alive_by_video_id (
            self,
            video_id:               int,
            with_relation_tables:   bool,
    ) -> list[VideoTagDto]:
        with self.conn.cursor (dictionary = True) as c:
            c.execute ("""
                    SELECT
                      id,
                      video_id,
                      tag_id,
                      tagged_at,
                      untagged_at
                    FROM
                      video_tags
                    WHERE
                      video_id = %s
                      AND (untagged_at IS NULL)
                    ORDER BY
                      id""", (video_id,))
            video_tags: list[VideoTagDto] = []
            for row in c.fetchall ():
                video_tags.append (self._create_dto_from_row (row, with_relation_tables))
            return video_tags

    def fetch_alive_by_ids (
            self,
            video_id:               int,
            tag_id:                 int,
            with_relation_tables:   bool,
    ) -> VideoTagDto | None:
        with self.conn.cursor (dictionary = True) as c:
            c.execute ("""
                    SELECT
                      id,
                      video_id,
                      tag_id,
                      tagged_at,
                      untagged_at
                    FROM
                      video_tags
                    WHERE
                      video_id = %s
                      AND tag_id = %s""", (video_id, tag_id))
            row = c.fetchone ()
            if row is None:
                return None
            return self._create_dto_from_row (row, with_relation_tables)

    def insert (
            self,
            video_tag:              VideoTagDto,
            with_relation_tables:   bool,
    ) -> None:
        with self.conn.cursor (dictionary = True) as c:
            c.execute ("""
                    INSERT INTO
                      video_tags(
                        video_id,
                        tag_id,
                        tagged_at,
                        untagged_at)
                    VALUES
                      (
                        %s,
                        %s,
                        %s,
                        %s)""", (video_tag.video_id, video_tag.tag_id,
                                 video_tag.tagged_at, video_tag.untagged_at))
            video_tag.id_ = c.lastrowid
            if with_relation_tables:
                if video_tag.video is not None:
                    VideoDao (self.conn).upsert (video_tag.video, True)
                if video_tag.tag is not None:
                    TagDao (self.conn).upsert (video_tag.tag)

    def upsert (
            self,
            video_tag:              VideoTagDto,
            with_relation_tables:   bool,
    ) -> None:
        with self.conn.cursor (dictionary = True) as c:
            c.execute ("""
                    INSERT INTO
                      video_tags(
                        video_id,
                        tag_id,
                        tagged_at,
                        untagged_at)
                    VALUES
                      (
                        %s,
                        %s,
                        %s,
                        %s)
                    ON DUPLICATE KEY UPDATE
                      video_id = VALUES(video_id),
                      tag_id = VALUES(tag_id),
                      tagged_at = VALUES(tagged_at),
                      untagged_at = VALUES(untagged_at)""", (video_tag.video_id,
                                                             video_tag.tag_id,
                                                             video_tag.tagged_at,
                                                             video_tag.untagged_at))
            video_tag.id_ = c.lastrowid
            if with_relation_tables:
                if video_tag.video is not None:
                    VideoDao (self.conn).upsert (video_tag.video, True)
                if video_tag.tag is not None:
                    TagDao (self.conn).upsert (video_tag.tag)

    def upsert_all (
            self,
            video_tags:             list[VideoTagDto],
            with_relation_tables:   bool,
    ) -> None:
        for video_tag in video_tags:
            self.upsert (video_tag, with_relation_tables)

    def untag_all (
            self,
            video_id:   int,
            tag_ids:    list[int],
            now:        datetime,
    ) -> None:
        if not tag_ids:
            return
        with self.conn.cursor (dictionary = True) as c:
            c.execute ("""
                    UPDATE
                      video_tags
                    SET
                      untagged_at = %%s
                    WHERE
                      video_id = %%s
                      AND tag_ids IN (%s)""" % ', '.join (['%s'] * len (tag_ids)), (now, video_id, *tag_ids))

    def _create_dto_from_row (
            self,
            row,
            with_relation_tables:   bool,
    ) -> VideoTagDto:
        video_tag = VideoTagDto (id_            = row['id'],
                                 video_id       = row['video_id'],
                                 tag_id         = row['tag_id'],
                                 tagged_at      = row['tagged_at'],
                                 untagged_at    = row['untagged_at'])
        if with_relation_tables:
            video_tag.video = VideoDao (self.conn).find (video_tag.video_id, True)
            video_tag.tag = TagDao (self.conn).find (video_tag.tag_id)
        return video_tag


@dataclass (slots = True)
class VideoTagDto:
    video_id:       int
    tag_id:         int
    tagged_at:      datetime
    id_:            int | None              = None
    untagged_at:    datetime | DbNullType   = DbNull
    video:          VideoDto | None         = None
    tag:            TagDto | None           = None


class TagDao:
    def __init__ (
            self,
            conn,
    ):
        self.conn = conn

    def find (
        self,
        tag_id:                 int,
    ) -> TagDto | None:
        with self.conn.cursor (dictionary = True) as c:
            c.execute ("""
                    SELECT
                      id,
                      name
                    FROM
                      tags
                    WHERE
                      id = %s""", (tag_id,))
            row = c.fetchone ()
            if row is None:
                return None
            return self._create_dto_from_row (row)

    def fetch_by_name (
            self,
            tag_name:   str,
    ) -> TagDto | None:
        with self.conn.cursor (dictionary = True) as c:
            c.execute ("""
                    SELECT
                      id,
                      name
                    FROM
                      tags
                    WHERE
                      name = %s""", (tag_name,))
            row = c.fetchone ()
            if row is None:
                return None
            return self._create_dto_from_row (row)

    def insert (
            self,
            tag:    TagDto,
    ) -> None:
        with self.conn.cursor (dictionary = True) as c:
            c.execute ("""
                    INSERT INTO
                      tags(name)
                    VALUES
                      (%s)""", (tag.name,))
            tag.id_ = c.lastrowid

    def upsert (
            self,
            tag:    TagDto,
    ) -> None:
        with self.conn.cursor (dictionary = True) as c:
            c.execute ("""
                    INSERT INTO
                      tags(name)
                    VALUES
                      (%s)
                    ON DUPLICATE KEY UPDATE
                      name = VALUES(name)""", (tag.name,))
            tag.id_ = c.lastrowid

    def _create_dto_from_row (
            self,
            row,
    ) -> TagDto:
        return TagDto (id_  = row['id'],
                       name = row['name'])


@dataclass (slots = True)
class TagDto:
    name:   str
    id_:    int | None  = None


class VideoHistoryDao:
    def __init__ (
            self,
            conn,
    ):
        self.conn = conn

    def fetch_by_video_id (
            self,
            video_id:               int,
            with_relation_tables:   bool,
    ) -> list[VideoHistoryDto]:
        with self.conn.cursor (dictionary = True) as c:
            c.execute ("""
                    SELECT
                      id,
                      video_id,
                      fetched_at,
                      views_count
                    FROM
                      video_histories
                    WHERE
                      video_id = %s""", (video_id,))
            video_histories: list[VideoHistoryDto] = []
            for row in c.fetchall ():
                video_histories.append (self._create_dto_from_row (row, with_relation_tables))
            return video_histories

    def insert (
            self,
            video_history:          VideoHistoryDto,
    ) -> None:
        with self.conn.cursor (dictionary = True) as c:
            c.execute ("""
                    INSERT INTO
                      video_histories(
                        video_id,
                        fetched_at,
                        views_count)
                    VALUES
                      (
                        %s,
                        %s,
                        %s)""", (video_history.video_id,
                                 video_history.fetched_at,
                                 video_history.views_count))

    def upsert (
            self,
            video_history:          VideoHistoryDto,
    ) -> None:
        with self.conn.cursor (dictionary = True) as c:
            c.execute ("""
                    INSERT INTO
                      video_histories(
                        video_id,
                        fetched_at,
                        views_count)
                    VALUES
                      (
                        %s,
                        %s,
                        %s)
                    ON DUPLICATE KEY UPDATE
                      video_id,
                      fetched_at,
                      views_count""", (video_history.video_id,
                                       video_history.fetched_at,
                                       video_history.views_count))

    def upsert_all (
            self,
            video_histories:        list[VideoHistoryDto],
    ) -> None:
        for video_history in video_histories:
            self.upsert (video_history)

    def _create_dto_from_row (
            self,
            row,
            with_relation_tables:   bool,
    ) -> VideoHistoryDto:
        video_history = VideoHistoryDto (id_            = row['id'],
                                         video_id       = row['video_id'],
                                         fetched_at     = row['fetched_at'],
                                         views_count    = row['views_count'])
        if with_relation_tables:
            video_history.video = VideoDao (self.conn).find (video_history.video_id, True)
        return video_history


@dataclass (slots = True)
class VideoHistoryDto:
    video_id:       int
    fetched_at:     datetime
    views_count:    int
    id_:            int | None      = None
    video:          VideoDto | None = None


class CommentDao:
    def __init__ (
            self,
            conn,
    ):
        self.conn = conn

    def fetch_by_video_id (
            self,
            video_id:               int,
            with_relation_tables:   bool,
    ) -> list[CommentDto]:
        with self.conn.cursor (dictionary = True) as c:
            c.execute ("""
                    SELECT
                      id,
                      video_id,
                      comment_no,
                      user_id,
                      content,
                      posted_at,
                      nico_count,
                      vpos_ms
                    FROM
                      comments
                    WHERE
                      video_id = %s""", (video_id,))
            comments: list[CommentDto] = []
            for row in c.fetchall ():
                comments.append (self._create_dto_from_row (row, with_relation_tables))
            return comments

    def upsert (
            self,
            comment:                CommentDto,
            with_relation_tables:   bool,
    ) -> None:
        with self.conn.cursor (dictionary = True) as c:
            c.execute ("""
                    INSERT INTO
                      comments(
                        video_id,
                        comment_no,
                        user_id,
                        content,
                        posted_at,
                        nico_count,
                        vpos_ms)
                    VALUES
                      (
                        %s,
                        %s,
                        %s,
                        %s,
                        %s,
                        %s,
                        %s)
                    ON DUPLICATE KEY UPDATE
                      video_id = VALUES(video_id),
                      comment_no = VALUES(comment_no),
                      user_id = VALUES(user_id),
                      content = VALUES(content),
                      posted_at = VALUES(posted_at),
                      nico_count = VALUES(nico_count),
                      vpos_ms = VALUES(vpos_ms)""", (comment.video_id,
                                                     comment.comment_no,
                                                     comment.user_id,
                                                     comment.content,
                                                     comment.posted_at,
                                                     comment.nico_count,
                                                     comment.vpos_ms))

    def upsert_all (
            self,
            comments:               list[CommentDto],
            with_relation_tables:   bool,
    ) -> None:
        for comment in comments:
            self.upsert (comment, with_relation_tables)

    def _create_dto_from_row (
            self,
            row,
            with_relation_tables:   bool,
    ) -> CommentDto:
        comment = CommentDto (id_           = row['id'],
                              video_id      = row['video_id'],
                              comment_no    = row['comment_no'],
                              user_id       = row['user_id'],
                              content       = row['content'],
                              posted_at     = row['posted_at'],
                              nico_count    = row['nico_count'],
                              vpos_ms       = row['vpos_ms'])
        if with_relation_tables:
            comment.video = VideoDao (self.conn).find (comment.video_id, True)
        return comment


@dataclass (slots = True)
class CommentDto:
    video_id:   int
    comment_no: int
    user_id:    int
    content:    str
    posted_at:  datetime
    id_:        int | None          = None
    nico_count: int                 = 0
    vpos_ms:    int | DbNullType    = DbNull
    video:      VideoDto | None     = None
    user:       UserDto | None      = None


class UserDao:
    def __init__ (
            self,
            conn,
    ):
        self.conn = conn

    def fetch_by_code (
            self,
            user_code:  str
    ) -> UserDto | None:
        with self.conn.cursor (dictionary = True) as c:
            c.execute ("""
                    SELECT
                      id,
                      code
                    FROM
                      users
                    WHERE
                      code = %s""", (user_code,))
            row = c.fetchone ()
            if row is None:
                return None
            return self._create_dto_from_row (row)

    def insert (
            self,
            user:   UserDto,
    ) -> None:
        with self.conn.cursor (dictionary = True) as c:
            c.execute ("""
                    INSERT INTO
                      users(code)
                    VALUES
                      (%s)""", (user.code,))
            user.id_ = c.lastrowid

    def _create_dto_from_row (
            self,
            row,
    ) -> UserDto:
        return UserDto (id_     = row['id'],
                        code    = row['code'])


@dataclass (slots = True)
class UserDto:
    code:   str
    id_:    int | None  = None


if __name__ == '__main__':
    main ()