Can't add custom type to table

[xOldeVx]

I have a playlist object that contains a video object, i'm trying to add a video to the playlist table and i'm getting compile error, here's the error:

Here's the convertor code:

class VideoConverter extends TypeConverter<Video, String> {
  const VideoConverter();

  @override
  Video fromSql(String fromDb) {
    return Video.fromJson(json.decode(fromDb) as Map<String, dynamic>);
  }

  @override
  String toSql(Video value) {
    return json.encode(value.toJson());
  }
}

And the playlist table:

class PlaylistDB extends Table {
  IntColumn get id => integer().autoIncrement()();

  TextColumn get title => text().named('title')();

  TextColumn get videos => text().named('video').map(const VideoConverter())();
}

How can i insert specific video/list of videos to the playlist table?

[Mike278]

The error is telling you that you need to wrap video in a Value. Have a look at the docs for updates, deletes, and inserts - the tl;dr is that Value is used to distinguish between "leave this column unchanged" when updating, "use the column's default value" when inserting, and "set this column to null" when inserting or updating.

[simolus3]

Could you check that you're on the latest drift version as well? After copying your table and type converter, drift generates this for me:

  PlaylistDBCompanion.insert({
    this.id = const Value.absent(),
    required String title,
    required Video videos,
  })

So ideally you should just be able to pass the video directly. Since videos is not nullable in the table, it should be a required value in the insert constructor of the companion.

A Value wrapper is used when you have the choice between an explicit value and a default that would be computed in the database. You can see this with the id column: You could set it to a fixed id (id: Value(3)) or use the auto-incremented value (id: Value.absent(), the default).

[Mike278]

videos is not nullable in the table

Oh right, I forgot Dart column definitions are non-null by default (which makes sense!)

[xOldeVx]

Thanks you, it's working! I'm saving a list of videos in the playlist object, it's working good, i can't find a way to remove specific video from the list, here's the code:

VideoModel video = VideoModel('videoId1', 'channelId', 'title');
await into(playlists).insert(PlaylistsCompanion.insert(
  title: 'video.title',
  videos: [video],
));

List<Playlist> result = await select(playlists).get();
await delete(playlists)..where((t) => t.videos);         <---- How remove specific video from List<Videos>
print(result);

class Playlists extends Table {
  IntColumn get id => integer().autoIncrement()();

  TextColumn get title => text().named('t')();

  TextColumn get videos => text().named('v').map(const VideoListConverter())();
}

class VideoListConverter extends TypeConverter<List<VideoModel>, String> {
  const VideoListConverter();

  @override
  List<VideoModel> fromSql(String fromDb) {
    return jsonDecode(fromDb).map((e) => VideoModel.fromJson(e)).toList().cast<VideoModel>();;
  }

  @override
  String toSql(List<VideoModel> value) {
    return json.encode(List<dynamic>.from(value.map((e) => e.toJson())));
  }
}

[simolus3]

For those queries, I'd generally recommend a more typical relational design, where you have three tables (videos, playlist, video-in-playlist). That makes the select a lot more complicated, but it's much easier to remove a specific video from a playlist.

In your design, I think the easiest way would be to:

1. Select videos from the playlist
2. Remove the video in Dart
3. Use an update to remove the video in the SQL.

This could look something like this:

await transaction(() async {
  final playlist = await (select(playlists)..where((row) => /* filter for the playlist where you want to delete a video */)).get();
  final videos = playlist.videos.toList();
  videos.remove(videoToRemove);
  await (update(playlists)..whereSamePrimaryKey(playlist)).write(PlaylistsCompanion(videos: Value(videos));
});

[dickermoshe]

No activity in over a year & seems to be resolved, closing