我收到这个错误:
数据库操作预计影响1行,但实际影响0行
向实体的集合添加新元素时。
Domain
项目中的基类:
public class Tour
{
private List<Stop> _stops;
public Guid Id { get; private set; }
public Tour(Guid id)
{
Id = id;
_stops = new List<Stop>();
}
public IReadOnlyList<Stop> Stops { get { return _stops; } }
public void AddStop(Stop newStop)
{
//some logic and checking
_stops.Add(newStop);
}
}
public class Stop
{
public Stop(Guid id)
{
Id = id;
}
public Guid Id { get; private set; }
}
我在Infrastructure
项目中的DbContext
:
public class TourDbContext : DbContext, ITourDbContext
{
protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
{
optionsBuilder.UseSqlServer("Server=(localdb)\mssqllocaldb;Database=db");
}
public DbSet<Tour> Tours { get; set; }
public DbSet<Stop> Stops { get; set; }
}
在Application
项目中调用AddStopToTour()
时引发异常。
DbContext
接口,基于:https://github.com/jasontaylordev/CleanArchitecture.
public interface ITourDbContext
{
public DbSet<Tour> Tours { get; set; }
public DbSet<Stop> Stops { get; set; }
Task<int> SaveChangesAsync(CancellationToken cancellationToken = default);
}
public class SomeClass
{
ITourDbContext _context;
public SomeClass(ITourDbContext context)
{
_context = context;
}
public async Task AddStopToTour(Guid id)
{
var tour = await _context.Tours
.Include(x => x.Stops)
.SingleOrDefaultAsync(e => e.Id == id);
tour.AddStop(new Stop(Guid.NewGuid());
await _context.SaveChangesAsync(); //Exception
}
}
EF Core难道不应该自动跟踪这些更改并在Stops表中添加一个新行吗?我是否缺少实体上的附加配置?
问题是,通过手动生成我的Id,新实体获得了Modified
状态,而不是Added
状态。修复是使用Fluent API的.ValueGeneratedNever()
方法和modelBuilder
。
请参阅:https://learn.microsoft.com/en-us/ef/core/what-is-new/ef-core-3.x/breaking-changes#detectchanges-遵守存储生成的密钥值