我尝试在具有强类型 ID 的模型上查询 Postgresql DB 并投影到模型。
无法理解为什么查询不起作用。
它抛出这个异常:
未处理的异常。系统.InvalidOperationException: “EF.Property(u3.Id, "ClientId")”的翻译失败。 查询源不是实体类型,或者实体类型上不存在指定的属性。
如果我从查询中删除强类型 ID 并使用普通 Guid,查询将正确执行并从数据库返回数据。
public class Program
{
public static void Main()
{
using var context = new EntityContext();
var query = (from client in context.Clients
let managers = from managerId in client.ManagerIds
join user in context.Users on managerId equals user.Id
select new { user.Id, user.Name }
select new { client, managers }).ToList();
}
}
public record UserId(Guid Value);
public record ClientId(Guid Value);
public class Client
{
public ClientId Id { get; set; }
public ICollection<UserId> ManagerIds { get; set; } = new List<UserId>();
}
public record User(UserId Id, string Name);
public class EntityContext : DbContext
{
public DbSet<Client> Clients { get; set; }
public DbSet<User> Users { get; set; }
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
modelBuilder.Entity<User>().HasKey(x => x.Id);
modelBuilder.Entity<User>()
.Property(x => x.Id)
.HasConversion(x => x.Value, x => new UserId(x));
modelBuilder.Entity<Client>().HasKey(x => x.Id);
modelBuilder.Entity<Client>()
.Property(x => x.Id)
.HasConversion(x => x.Value, x => new ClientId(x));
modelBuilder.Entity<Client>()
.OwnsMany(
client => client.ManagerIds,
ownedNavigationBuilder =>
{
ownedNavigationBuilder
.WithOwner()
.HasForeignKey("ClientId");
ownedNavigationBuilder
.Property(x => x.Value)
.HasColumnName("ManagerId");
}
);
}
}
我不是 100% 确定,但这种关系看起来并不正确:
modelBuilder.Entity<Client>()
.OwnsMany(
client => client.ManagerIds,
ownedNavigationBuilder =>
{
ownedNavigationBuilder
.WithOwner()
.HasForeignKey("ClientId");
ownedNavigationBuilder
.Property(x => x.Value)
.HasColumnName("ManagerId");
}
);
OwnsMany
/HasMany
用于实体之间的关系,因此我希望客户端有一个 ICollection<User> Managers { get; } = [];
而不是 UserId 的集合。 EF 期望记录是一个实体而不是 GUID。我怀疑 EF 可以在客户端行中存储 GUID 列表,但正确规范化的多对多关系会更好。