EF CPT5的域建模与映射 [英] Domain Modeling and Mapping with EF CPT5

问题描述

我正在设计出一张有照片集合的相册。每张专辑都将收录一张照片和一张拇指照片。这是我所拥有的，但EF似乎并不喜欢。我使用EF CPT5

I am trying to model out a album that has a collection of photos. Each Album will have a collection of Photos and a Photo that is a thumb. This is what I have but EF does not seem to like it. I am using EF CPT5

模型：

public class Album : IEntity {
  private DateTime _dateCreated;
  public Album() {
    _dateCreated = SystemTime.Now();
    Photos = new List<Photo>();
  }

  public long Id { get; set; }
  public string Name { get; set; }
  public string Location { get; set; }
  public DateTime DateCreated {  get { return _dateCreated; }  set { _dateCreated = value; } }

  public virtual Site Site { get; set; }
  public virtual Photo Thumbnail { get; set; }
  public long ThumbnailId { get; set; }
  public virtual ICollection<Photo> Photos { get; set; }
 }



public class Photo : IEntity {
  public Photo() {
    _dateCreated = SystemTime.Now();
  }
  private DateTime _dateCreated;
  public long Id { get; set; }
  public string Caption { get; set; }
  public string FileName { get; set; }
  public DateTime DateCreated<br/>{ get { return _dateCreated; } set { _dateCreated = value; } }
  public long AlbymId { get; set; }
  public virtual Album Album { get; set; }
 }

映射代码

public class AlbumMap : EntityTypeConfiguration<Album> {
  public AlbumMap() {
    HasRequired(x => x.Thumbnail).WithMany().HasForeignKey(a => a.ThumbnailId).WillCascadeOnDelete(false);
        Property(x => x.Location).IsVariableLength().HasMaxLength(80);
        Property(x => x.Name).IsVariableLength().HasMaxLength(80).IsRequired();
    }
 }

 public class PhotoMap : EntityTypeConfiguration<Photo> {
  public PhotoMap() {
    HasRequired(p => p.Album).WithMany(a => a.Photos).HasForeignKey(p => p.AlbymId);
    Property(x => x.FileName).IsVariableLength().HasMaxLength(255).IsRequired();
    Property(x => x.Caption).IsVariableLength().HasMaxLength(255);
    Property(x => x.DateCreated);
    ToTable("SiteAlbumPhotos");
    }
 }

上下文

public class Database : ObjectContext {

        public Database(EntityConnection connection) : base(connection) {
            ContextOptions.LazyLoadingEnabled = true;
            ContextOptions.ProxyCreationEnabled = true;
        }

        private IObjectSet<User> _users;
        private IObjectSet<Site> _sites;
        private IObjectSet<SiteDonation> _donations;
        private IObjectSet<SiteAnnouncement> _siteAnnouncements;
        private IObjectSet<SiteData> _siteData;
        private IObjectSet<SiteLink> _siteLinks;
        private IObjectSet<SitePost> _sitePosts;
        private IObjectSet<Theme> _theme;
        private IObjectSet<Album> _siteAlbums;
        private IObjectSet<Photo> _siteAlbumPhotos;
        private IObjectSet<CommunityPost> _communityPosts;
        private IObjectSet<CommunityComment> _communityComments;

        public IObjectSet<User> Users {
            get{ return _users ?? (_users = ObjectSet<User>()); }
        }
        public IObjectSet<Album> SiteAlbums {
            get { return _siteAlbums ?? (_siteAlbums =  ObjectSet<Album>()); }
        }
        public IObjectSet<Photo> SiteAlbumsPhotos {
            get { return _siteAlbumPhotos ?? (_siteAlbumPhotos = ObjectSet<Photo>()); }
        }
        public IObjectSet<Site> Sites {
            get{ return _sites ?? (_sites = ObjectSet<Site>()); }
        }

        public IObjectSet<SiteDonation> SiteDonations {
            get { return _donations ?? (_donations = ObjectSet<SiteDonation>()); }
        }

        public IObjectSet<SiteAnnouncement> SiteAnnouncements {
            get { return _siteAnnouncements ?? (_siteAnnouncements = ObjectSet<SiteAnnouncement>()); }
        }

        public IObjectSet<SiteData> SiteData {
            get { return _siteData ?? (_siteData = ObjectSet<SiteData>()); }
        }

        public IObjectSet<SiteLink> SiteLinks {
            get { return _siteLinks ?? (_siteLinks = ObjectSet<SiteLink>()); }
        }

        public IObjectSet<SitePost> SitePosts {
            get { return _sitePosts ?? (_sitePosts = ObjectSet<SitePost>()); }
        }

        public IObjectSet<Theme> Themes { 
            get { return _theme ?? (_theme = ObjectSet<Theme>()); }
        }
        public IObjectSet<CommunityPost> CommunityPosts {
            get { return _communityPosts ?? (_communityPosts = ObjectSet<CommunityPost>()); }
        }
        public IObjectSet<CommunityComment> CommunityComments {
            get { return _communityComments ?? (_communityComments = ObjectSet<CommunityComment>()); }
        }

        public virtual IObjectSet<T> ObjectSet<T>() where T : class, IEntity {
            return CreateObjectSet<T>();
        }
        public virtual void Commit() {
            SaveChanges();
        }
    }

DatabaseFactory >

DatabaseFactory

public class DatabaseFactory : Disposable, IDatabaseFactory
    {
        private static readonly ModelBuilder builder = CreateBuilder();
        private readonly DbProviderFactory _providerFactory;
        private readonly string _connectionString;
        private Database _database;
        //
        public DatabaseFactory(DbProviderFactory providerFactory, string connectionString)
        {
            Check.Argument.IsNotNull(providerFactory, "providerFactory");
            Check.Argument.IsNotNullOrEmpty(connectionString, "connectionString");
            _providerFactory = providerFactory;
            _connectionString = connectionString;
        }
        //
        public Database Get()
        {
            if(_database == null)
            {
                var connection = _providerFactory.CreateConnection();
                connection.ConnectionString = _connectionString;
                //_database = builder.CreateModel(connection); LEG 1 CPT 3
                //var ctx = dbModel.CreateObjectContext<ObjectContext>(_connectionString); LEG 1 CPT 3
                //var modelBuilder = builder.CreateModel(); LEG 2 CPT 4
                //_database = modelBuilder.CreateObjectContext<Database>(connection); LEG 2 CPT 4
                //_database = modelBuilder.CreateObjectContext<Database>(connection); LEG 2 CPT 4
                var modelBuilder = builder.Build(connection);
                var dbModel = new DbModel(modelBuilder);
                _database = dbModel.CreateObjectContext<Database>(connection);

            }

            return _database;
        }
        //
        protected override void DisposeCore()
        {
            if (_database != null)
            {
                _database.Dispose();
            }
        }
        //
        private static ModelBuilder CreateBuilder()
        {
            //ContextBuilder<Database> contextBuilder = new ContextBuilder<Database>();
            var contextBuilder = new ModelBuilder();
            //IEnumerable<Type> configurationTypes = typeof(DatabaseFactory)
            //    .Assembly
            //    .GetTypes()
            //    .Where(type => type.IsPublic && type.IsClass && !type.IsAbstract && !type.IsGenericType && typeof(StructuralTypeConfiguration).IsAssignableFrom(type) && (type.GetConstructor(Type.EmptyTypes) != null));

            //foreach (StructuralTypeConfiguration configuration in configurationTypes.Select(type => (StructuralTypeConfiguration)Activator.CreateInstance(type)))
            //{
            //    contextBuilder.Configurations.Add(configuration);
            //}
            contextBuilder.Configurations.Add(new CommunityCommentMap());
            contextBuilder.Configurations.Add(new CommunityPostMap());
            contextBuilder.Configurations.Add(new SiteAlbumMap());
            contextBuilder.Configurations.Add(new SiteAlbumPhotoMap());
            contextBuilder.Configurations.Add(new SiteAnnouncementMap());
            contextBuilder.Configurations.Add(new SiteDataMap());
            contextBuilder.Configurations.Add(new SiteDonationMap());
            contextBuilder.Configurations.Add(new SiteLinkMap());
            contextBuilder.Configurations.Add(new SiteMap());
            contextBuilder.Configurations.Add(new SitePostMap());
            contextBuilder.Configurations.Add(new ThemeMap());
            contextBuilder.Configurations.Add(new UserMap());
            return contextBuilder;
        }
    }

我是否正确建模和映射？我需要能够创建一个新的相册而不指定缩略图。到目前为止，它一直工作，直到我尝试添加一个缩略图，然后我得到这个错误：

Am I Modeling and Mapping this correctly? I need to be able to create a new Album without specifying a Thumbnail. As of now, it all works till I try to add a Thumbnail, then I get this error:

System.Data.UpdateException：无法确定依赖的有效排序操作。由于外键约束，模型要求或存储生成值，可能存在依赖关系。

System.Data.UpdateException: Unable to determine a valid ordering for dependent operations. Dependencies may exist due to foreign key constraints, model requirements, or store-generated values.

在System.Data.Mapping.Update.Internal.UpdateTranslator.DependencyOrderingError（IEnumerable` 1个余数）
在System.Data.Mapping.Update.Internal.UpdateTranslator.ProduceCommands（）
在System.Data.Mapping.Update.Internal.UpdateTranslator.Update（IEntityStateManager stateManager，IEntityAdapter适配器）
在System.Data.Objects.ObjectContext.SaveChanges（SaveOptions选项）
在PostHope.Infrastructure.DataAccess.Database.Commit（）在Database.cs：行74
在PostHope.Infrastructure.DataAccess。 BuildDatabase.cs中的IntegrationTests.BuildDatabase.Add_test_data_to_database（）：第252行

at System.Data.Mapping.Update.Internal.UpdateTranslator.DependencyOrderingError(IEnumerable`1 remainder) at System.Data.Mapping.Update.Internal.UpdateTranslator.ProduceCommands() at System.Data.Mapping.Update.Internal.UpdateTranslator.Update(IEntityStateManager stateManager, IEntityAdapter adapter) at System.Data.Objects.ObjectContext.SaveChanges(SaveOptions options) at PostHope.Infrastructure.DataAccess.Database.Commit() in Database.cs: line 74 at PostHope.Infrastructure.DataAccess.IntegrationTests.BuildDatabase.Add_test_data_to_database() in BuildDatabase.cs: line 252

任何帮助都会很棒！

推荐答案

我们通过EF CTP4 这里 。现在这里是EF CTP5的更新，它已经是 发布

We tackled this question by EF CTP4 here. Now here is the update for EF CTP5 which has been released earlier today.

public class Photo 
{
    public long PhotoId { get; set; }        
    [MaxLength(255)]
    public string Caption { get; set; }        
    [MaxLength(255)][Required]
    public string FileName { get; set; }        
    public DateTime DateCreated { get; set; }
    public long AlbumId { get; set; }        
    public virtual Album Album { get; set; }
}

[Table("SiteAlbumPhotos")]
public class Album 
{
    public long AlbumId { get; set; }        
    [MaxLength(80)][Required]
    public string Name { get; set; }        
    [MaxLength(80)]
    public string Location { get; set; }        
    public DateTime DateCreated { get; set; }                
    public long ThumbnailId { get; set; }                
    public virtual Photo Thumbnail { get; set; }                
    public virtual ICollection<Photo> Photos { get; set; }
}  

public class PhotoMap : EntityTypeConfiguration<Photo> {
    public PhotoMap() {            
        HasRequired(p => p.Album).WithMany(a => a.Photos)
                                 .HasForeignKey(p => p.AlbumId);
    }
}

public class AlbumMap : EntityTypeConfiguration<Album> {
    public AlbumMap() {
        HasRequired(a => a.Thumbnail).WithMany()
                                     .HasForeignKey(a => a.ThumbnailId)
                                     .WillCascadeOnDelete(false);
    }
}

public class MyContext : DbContext {
    public DbSet<Photo> Photos { get; set; }
    public DbSet<Album> Albums { get; set; }

    protected override void OnModelCreating(ModelBuilder modelBuilder) {
        modelBuilder.Configurations.Add<Photo>(new PhotoMap());
        modelBuilder.Configurations.Add<Album>(new AlbumMap());
    }
}

这个数据库模式的结果是：

Which results to this DB schema:

这篇关于EF CPT5的域建模与映射的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！