[英]Entity Framework Core: get related data
在我正在开发的应用程序中,我的用户可以拥有播放列表。 他们可以访问自己的播放列表(然后他们将成为其所有者)或与他们所属的团队相关的播放列表。 我的实体如下所示(Id 是 Guid 类型,从实体 AuditEntity 继承):
public class Team : AuditEntity
{
public Team()
{
Playlists = new HashSet<Playlist>();
}
public string TeamName { get; set;}
public Guid OwnerId { get; set; }
public virtual AppUser Owner { get; set; }
public ICollection<TeamsAppUsers> Members { get; set; }
public ICollection<Playlist> Playlists { get; private set; }
}
public class Playlist : AuditEntity
{
public string PlaylistName { get; set; }
public Guid OwnerId { get; set; }
public virtual AppUser Owner { get; set; }
public Team Team { get; set; }
}
public class TeamsAppUsers
{
public Guid AppUserId { get; set; }
public AppUser Member { get; set; }
public Guid TeamId { get; set; }
public Team Team { get; set; }
}
我需要所有播放列表(并且只有一次),其中用户是所有者或与播放列表相关的团队成员。
对于我拥有的OwnerId
:
var playlists = await _context.Playlists
.Where(pl => pl.OwnerId == userId)
.ToListAsync()
我如何扩展此声明,以便还包括用户是相关团队成员的播放列表?
您可以有利地将代码移动到您的上下文中并使用 EntityFramework,我允许自己在几个地方编辑您的类型以便能够建立模型构建关系,如下所示:
public class PlaylistsDbContext : DbContext
{
DbSet Teams { get; set; }
DbSet Playlists { get; set; }
DbSet AppUsers { get; set; }
//Not needed
DbSet TeamAppUsers { get; set; }
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
modelBuilder.Entity().HasKey(k => k.Id);
modelBuilder.Entity().HasKey(k => k.Id);
modelBuilder.Entity().HasKey(k => k.AppUserId);
//Not needed
modelBuilder.Entity().HasKey(k => new { k.AppUserId, k.TeamId });
modelBuilder.Entity().HasMany(x => x.Playlists).WithOne(y => y.Team);
modelBuilder.Entity()
.HasOne(x => x.Owner)
.WithMany(y => y.PlayLists)
.HasPrincipalKey(k => k.AppUserId)
.HasForeignKey(f => f.OwnerId);
modelBuilder.Entity()
.HasOne(x => x.Team)
.WithMany(y => y.Playlists)
.HasPrincipalKey(p => p.Id)
.HasForeignKey(f => f.TeamId);
//These relationship tables can be omitted, as entity framework can handle that for You
//Then you can also drop the explicit foreign key fields
base.OnModelCreating(modelBuilder);
}
public List GetUserPlaylists(Guid userId)
{
return Playlists.Include(x => x.Owner).Include(y => y.Team)
.Where(z => z.Owner.AppUserId == userId
|| z.Team.Members.Any(m => m.AppUserId == userId))
.Distinct()
.ToList();
}
}
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