I'm trying to catch WPF using MVVM pattern, where my set of models is implementing ObservableCollection as well as Entity Framework's DbContext.
My project is quite simple movies database (looking for movies on disc, getting info about these movies from web, and so on...).
I will be glad for any notes and recommendations for what to change / avoid in future.
I am especially afraid about my concept of MovieSet, which is "common implementation" of ObservableCollection & DbContext. Actually it works but I feel that it could be implemented in better way.
- Movie model
My model (Movie) implements commonly presented class ObservableObject and calls OnPropertyChanged(PropertyName) for whatever its property change.
MovieSet collection
/// <summary> /// MoviesSet - ObservableCollection of Movies synchronized with DbSet of Movies /// </summary> public class MoviesSet : ObservableCollection<Movie> { public class MoviesContext : DbContext { public DbSet<Movie> Movies { get; set; } public MoviesContext() : base("MoviesContext") { // allows to recreate database if model changes Database.SetInitializer<MoviesContext> (new DropCreateDatabaseIfModelChanges<MoviesContext>()); // allows to use properly "AttachDBFilename" from Connection strings AppDomain.CurrentDomain.SetData("DataDirectory", System.IO.Directory.GetCurrentDirectory()); } } private MoviesContext context = new MoviesContext(); /// <summary> /// Save context to database /// </summary> public void SaveContext() { context.SaveChanges(); } /// <summary> /// Add new movie to context /// </summary> /// <param name="movie"></param> public void AddMovie(Movie movie) { if ((context.Movies.Where(x => x.OrigName == movie.OrigName)).FirstOrDefault<Movie>() == null) { Add(movie); if (!string.IsNullOrEmpty(movie.OrigName)) { context.Movies.Add(movie); context.Entry(movie).State = EntityState.Added; } } } /// <summary> /// Notify modification of Movie object /// </summary> /// <param name="movie"></param> public void NotifyMovieModified(Movie movie) { if ((context.Movies.Where(x => x.OrigName == movie.OrigName)).FirstOrDefault<Movie>() != null) { context.Entry(movie).State = EntityState.Modified; } else { context.Entry(movie).State = EntityState.Added; } } /// <summary> /// Delete movie from context /// </summary> /// <param name="movie"></param> public void DeleteMovie(Movie movie) { Remove(movie); context.Entry(movie).State = EntityState.Deleted; context.Movies.Remove(movie); } /// <summary> /// Load context from database /// </summary> public void LoadContext() { context.Movies.Load(); foreach (Movie movie in context.Movies) { Add(movie); } } }ViewModel
/// <summary> /// Movie model /// </summary> public class ViewModel : Mvvm.ObservableObject { MovieFileProcessor fileProc; public ICommand FindMoviesCommand { get; set; } // find all movie files cmd public ICommand DownloadDataCommand { get; set; } // download all unknown movies data cmd public ICommand PlayVideoCommand { get; set; } // play selected movie cmd public ICommand VisitWebCommand { get; set; } // visit selected movie web page cmd public ICommand DeleteCommand { get; set; } // delete selected movie cmd public ICommand CopyCommand { get; set; } // copy selected movie cmd public ICommand FormatFileNameCommand { get; set; } // format selected movie files cmd // observable and serializable set of Movies public MoviesSet Movies { get; set; } // actually selected movie obj private object selectedMovie; public object SelectedMovie { get { return selectedMovie; } set { if (selectedMovie != value) { selectedMovie = value; OnPropertyChanged("SelectedMovie"); } } } // application configuration private NameValueCollection appCfg = ConfigurationManager.GetSection("appCfg") as NameValueCollection; public ViewModel() { FindMoviesCommand = new Mvvm.RelayCommand(FindMovieFiles); DownloadDataCommand = new Mvvm.RelayCommand(DownloadMoviesData); PlayVideoCommand = new Mvvm.RelayCommand(PlayVideo); VisitWebCommand = new Mvvm.RelayCommand(VisitWeb); DeleteCommand = new Mvvm.RelayCommand(DeleteMovie); CopyCommand = new Mvvm.RelayCommand(CopyMovie); FormatFileNameCommand = new Mvvm.RelayCommand(FormatFileName); fileProc = new MovieFileProcessor(appCfg["MoviesDir"]); Movies = new MoviesSet(); // load Movies context from database Movies.LoadContext(); } /// <summary> /// Delete selected movie /// </summary> /// <param name="obj">SelectedMovie</param> private void DeleteMovie(object obj) { try { fileProc.Delete(obj as Movie); } catch { } Movies.DeleteMovie(obj as Movie); Movies.SaveContext(); } /// <summary> /// Copy movie to another directory /// </summary> /// <param name="obj">SelectedMovie</param> private void CopyMovie(object obj) { throw new NotImplementedException(); } /// <summary> /// Rename selected movie video file (& subtitles file, & subdirectory) /// </summary> /// <param name="obj">SelectedMovie</param> private void FormatFileName(object obj) { fileProc.Rename(obj as Movie); Movies.NotifyMovieModified(obj as Movie); Movies.SaveContext(); } /// <summary> /// Visit web page of selected movie /// </summary> /// <param name="obj">SelectedMovie</param> private void VisitWeb(object obj) { System.Diagnostics.Process.Start((obj as Movie).WebPage); } /// <summary> /// Play selected movie /// </summary> /// <param name="obj">SelectedMovie</param> private void PlayVideo(object obj) { Process.Start(appCfg["VideoPlayerPath"], (obj as Movie).VideoFile.ToString() + " -f"); } /// <summary> /// Find movie files in movies directory /// </summary> /// <param name="obj">Not used</param> public void FindMovieFiles(object obj) { foreach (Movie movie in fileProc.FindMovies()) { Movies.AddMovie(movie); } // Movies context not saved because OrigName (Primary Key) is empty at this moment } /// <summary> /// Download data from repository /// </summary> /// <param name="obj">Not used</param> public void DownloadMoviesData(object obj) { CsfdDataMiner miner = new CsfdDataMiner(); new Task(() => { foreach (Movie movie in Movies.Where(x => string.IsNullOrEmpty(x.OrigName))) { movie.WebPage = miner.GetMoviePage(movie.VideoFile.Name); miner.GetMovieData(movie); Movies.NotifyMovieModified(movie); } Movies.SaveContext(); }).Start(); } }View - for completness
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="*"></RowDefinition>
<RowDefinition Height="Auto"></RowDefinition>
</Grid.RowDefinitions>
<DataGrid Grid.Row="0" x:Name="gridMovies" AutoGenerateColumns="False" Padding="10" CanUserAddRows="False" SelectionUnit="FullRow" SelectionMode="Single"
PreviewKeyDown="gridMovies_PreviewKeyDown" CanUserDeleteRows="False" IsReadOnly="True"
ItemsSource="{Binding Movies}" SelectedItem="{Binding SelectedMovie}">
<DataGrid.CellStyle>
<Style TargetType="DataGridCell">
<!--Disable highlight of current selected cell-->
<Setter Property="BorderThickness" Value="0"/>
</Style>
</DataGrid.CellStyle>
<DataGrid.Columns>
<DataGridTextColumn Binding="{Binding VideoFile}" Header="VideoFile" />
<DataGridTextColumn Binding="{Binding HasSubtitles}" Header="Subtitles" />
<DataGridTextColumn Binding="{Binding OrigName}" Header="Name" />
<DataGridTextColumn Binding="{Binding LocalName}" Header="Local Name" />
<DataGridTextColumn Binding="{Binding Year}" Header="Year" />
<DataGridTextColumn Binding="{Binding CountriesStrings}" Header="Countries" />
<DataGridTextColumn Binding="{Binding GenresStrings}" Header="Genres" />
<DataGridTextColumn Binding="{Binding Rating}" Header="Rating" />
</DataGrid.Columns>
<DataGrid.ContextMenu>
<ContextMenu IsEnabled="{Binding Movies.Count}">
<MenuItem Command="{Binding PlayVideoCommand}" CommandParameter="{Binding SelectedMovie}" Header="Play Video"/>
<MenuItem Command="{Binding VisitWebCommand}" CommandParameter="{Binding SelectedMovie}" Header="Visit web"/>
<MenuItem Command="{Binding DeleteCommand}" CommandParameter="{Binding SelectedMovie}" Header="Delete movie"/>
<MenuItem Command="{Binding FormatFileNameCommand}" CommandParameter="{Binding SelectedMovie}" Header="Format file names"/>
<MenuItem Command="{Binding CopyCommand}" CommandParameter="{Binding SelectedMovie}" Header="Copy movie"/>
</ContextMenu>
</DataGrid.ContextMenu>
</DataGrid>
<Grid Grid.Row="2" >
<Grid.ColumnDefinitions>
<ColumnDefinition></ColumnDefinition>
<ColumnDefinition></ColumnDefinition>
<ColumnDefinition></ColumnDefinition>
</Grid.ColumnDefinitions>
<Button Grid.Column="1" Name="btnFindMovies" Content="Find Movies" Command="{Binding FindMoviesCommand}"></Button>
<Button Grid.Column="2" Name="btnDwnldData" Content="Download Data" Command="{Binding DownloadDataCommand}"></Button>
</Grid>
</Grid>
