asp.net-core - EF Core 尝试添加新记录而不是更新 1:many 关系

Question

我不确定为什么在尝试创建实体时 1:many EF 尝试在 Asp Net Users 中添加新条目而不是更新 1:many

我有一个user有很多items

SqlException：违反主键约束“PK_AspNetUsers”。无法在对象“dbo.AspNetUsers”中插入重复键。重复键值为 (cdbb1f2f-ddcf-40c0-97ec-f50f8049d87a)。

public class Context : IdentityDbContext
{
    public Context(DbContextOptions options) : base(options)
    {
    }

    public DbSet<User> Users { get; set; }

    public DbSet<Item> Items { get; set; }

    public DbSet<File> Files { get; set; }
}

---

public class User : IdentityUser
{
    public List<Item> Items { get; set; } = new List<Item>();
}

---

public class Item
{
    private Item()
    {

    }

    public Item(string title, User owner, File file)
    {
        Title = title;
        Owner = owner;
        File = file;
    }

    public int Id { get; private set; }

    public string Title { get; set; }

    public User Owner { get; set; }

    public File File { get; set; }

    public DateTime CreationDate { get; } = DateTime.Now;
}

---

这就是问题所在：

var fileResult = await _file.SaveFile(input.File);
var item = new Item(input.Title, user, fileResult.File);

user.Items.Add(item);
await _context.Items.AddAsync(item);
await _context.SaveChangesAsync();

用户加载：

public User GetUser()
{
    return _context.Users.FirstOrDefault(x => x.UserName == _http.HttpContext.User.Identity.Name);
}

我试过了：

当我改变

public Item(string title, User owner, File file)
{
    Title = title;
    Owner = owner;
    File = file;
}

只是：

public Item(string title, File file)
{
    Title = title;
    File = file;
}

并让它由以下人员处理：

user.Items.Add(item);

那么 DB 中的 OwnerId 为空

使用：

protected override void OnModelCreating(ModelBuilder modelBuilder)
{
    base.OnModelCreating(modelBuilder);

    modelBuilder.Entity<User>()
        .HasMany(x => x.Items)
        .WithOne(x => x.Owner);

    modelBuilder.Entity<Item>().HasOne(x => x.Owner);
}

也无济于事

标签： asp.net-coreentity-framework-core

Answer 1

问题是由ServiceLifetimeDbContext 引起的

因为 User 被加载Controller然后Service被抛出，负责业务逻辑

我变了

(options => options.UseSqlServer(Configuration["Database:ConnectionString"]), ServiceLifetime.Transient);

到

(options => options.UseSqlServer(Configuration["Database:ConnectionString"]), ServiceLifetime.Scoped);

它工作正常。