我有一个WPF应用程序,其中必须有两个数据网格。根据第一个数据网格中的选择,第一个显示专辑,第二个对应的歌曲。我还可以添加一个相册,然后将其保存到数据库中。现在,我想在第一个数据网格中选择一个专辑,然后在第二个数据网格中向该专辑添加一首歌曲。所有歌曲在我的数据库中都有一个AlbumID作为外键。在将歌曲添加到数据库时,我不知道如何处理此参数AlbumID,我的查询会按预期崩溃。 我想知道如何告诉SongViewModel添加具有SelectedAlbum给定的AlbumID的歌曲。
查询添加相册:
public AlbumData AddAlbumEntry(AlbumData albumData)
{
album albumEntry = new album
{
AlbumName = albumData.AlbumName,
Year = albumData.AlbumYear,
};
_context.albums.Add(albumEntry);
_context.SaveChanges();
return new AlbumData
{
AlbumID = albumEntry.AlbumID,
AlbumYear = albumEntry.Year,
AlbumName = albumEntry.AlbumName,
};
}
查询添加歌曲:
public SongData AddSongEntry(SongData songData)
{
song songEntry = new song
{
SongName = songData.SongName,
SongNumber = songData.SongNumber,
};
_context.songs.Add(songEntry);
_context.SaveChanges();
return new SongData
{
SongID = songEntry.SongID,
SongNumber = songEntry.SongNumber,
SongName = songEntry.SongName,
};
}
AlbumViewModel连接到View:
public AlbumData AddAlbumEntry(AlbumData albumData)
{
var controller = new BandManagerController();
return controller.AddAlbumEntry(albumData);
}
public void AlbumToDatabase(AlbumData data)
{
AddAlbumEntry(data);
ExecuteCancelCommand();
}
要连接到视图的SongViewModel:
public SongData AddSongEntry(SongData songData)
{
var controller = new BandManagerController();
return controller.AddSongEntry(songData);
}
public void SongToDatabase(SongData data)
{
AddSongEntry(data);
ExecuteCancelCommand();
}
我还有一个SelectedAlbum属性来填充SongList:
public AlbumViewModel SelectedAlbum
{
get
{
return _selectedAlbum;
}
set
{
if (_selectedAlbum != value)
{
_selectedAlbum = value;
}
NotifyPropertyChanged("SelectedAlbum");
}
}
答案 0 :(得分:0)
我会尝试通过创建易于绑定到ui的View模型来尝试。视图模型应具有SelectedAlbum和SelectedSong属性,因此在创建新歌曲时,视图模型中将已经具有有关所选专辑的信息,然后可以在歌曲模型上设置专辑ID。
class ViewModel : BindableBase
{
private IDatabase _database;
private Album _album;
private Song _song;
public ObservableCollection<Album> Albums { get; private set; }
public ObservableCollection<Song> AlbumSongs { get; private set; }
public ICommand AddAlbumCommand {get; private set;}
public ICommand AddSongCommand {get; private set;}
public Album SelectedAlbum
{
get => _album;
set { LoadAlbumSongs(album); SetProperty(ref _album, value); }
}
public Song SelectedSong
{
get => _song;
set => SetProperty(ref _song, value);
}
public ViewModel(IDatabase database)
{
_database = database;
Albums = new ObservableCollection<Album>();
AlbumSongs = new ObservableCollection<Song>();
AddAlbumCommand = new RelayCommand (() => AddNewAlbum(), () => true);
AddSongCommand = new RelayCommand (() => AddNewSong(), () => SelectedAlbum != null);
}
public void AddNewAlbum()
{
SelectedAlbum = new Album();
}
public void AddNewSong()
{
SelectedSong = new Song();
SelectedSong.AlbumID = SelectedAlbum.AlbumID;
}
public void SaveAlbum()
{
if (SelectedAlbum.ID == 0) {
Albums.Add(SelectedAlbum);
}
_database.SaveAlbum(SelectedAlbum);
}
public void SaveSong()
{
if (SelectedSong.ID == 0) {
AlbumSongs.Add(SelectedSong);
}
_database.SaveSong(SelectedSong);
}
}
答案 1 :(得分:0)
我找到了解决方案。在AlbumListViewModel中,我打开可以添加歌曲的对话框。我通过选定专辑将SongModel中的AlbumId绑定到我的AlbumModel中的AlbumID。现在,我可以选择一个专辑并添加具有相应专辑ID的歌曲。使用“添加”按钮添加歌曲的命令的方法如下:
private void AddSong()
{
addSong.ShowDialog(new SongViewModel(new SongData { AlbumID = SelectedAlbum.AlbumID }));
}