c# - Ef 核心不跟踪子集合的更改

Question

我有这些模型

public class WarehouseAllocation
{
   public int Id { get; set; }
   public Warehouse Warehouse { get; set; }
   public IList<Dispatch> Dispatches { get; set; }
   //---- removed other properties for brevity
}

public class Dispatch 
{
   public int Id { get; set; }
   public IList<DispatchDetail> DispatchDetails { get; set; }
   //---- removed other properties for brevity
}

在数据库上，

Dispatch 有一个外键 WarehouseAllocationId 引用 WarehouseAllocation 表。

我使用 Fluent API 将模型映射到数据库，如下所示:

modelBuilder.Entity<WarehouseAllocation>(m =>
{
    m.ToTable("WarehouseAllocation");

    m.Property(wa => wa.Id).HasColumnName("WarehouseAllocationId")
         .ValueGeneratedOnAdd();

    m.HasKey(wa => wa.Id);

    m.HasOne(wa => wa.Warehouse)
        .WithMany()
        .HasForeignKey("WarehouseId");

    m.HasMany(w => w.Dispatches)
        .WithOne();
});

modelBuilder.Entity<Dispatch>(m =>
{
    m.ToTable("Dispatch");

    m.Property(wa => wa.Id).HasColumnName("DispatchId")
         .ValueGeneratedOnAdd();

    m.HasKey(wa => wa.Id);
});

当我打电话dbContext.WarehouseAllocations.Include(w => w.Dispatches).ThenInclude(w => w.DispatchDetails).ToList(),Ef core 检索所有仓库分配及其调度，包括详细信息。

问题是当我使用这个方法时:

var warehouseAllocation = dbContext.WarehouseAllocations
    .Include(w => w.Dispatches)
    .ThenInclude(d => d.DispatchDetails)
    .SingleOrDefault(w => w.Id == warehouseAllocationId);

warehouseAllocation.Dispatches.Add(new Dispatch
{
   //--including other properties
   DispatchDetails = new List<DispatchDetail> {
       new DispatchDetail
       {
          //--other properties
       }
   }
});

// call another query that includes WarehouseAllocation

dbContext.ChangeTracker.HasChanges() // this is false

dbContext.SaveChanges() // this keeps returning zero

为什么没有检测到更改？

更新:

在进行更改之后调用 SaveChanges() 之前，为了业务事件，我调用了一个包含仓库分配的 LINQ 查询。 Ef 核心是否会覆盖当前实体状态？

Answer 1

问题是，我在调用 SaveChanges() 之前进行了另一个包含仓库分配的查询。

即

var shipment = _myDbContext.Shipments
                .Include(s => s.WarehouseAllocations)
                .ThenInclude(s => s.Dispatches)
                .ThenInclude(s => s.DispatchDetails)
                .Include(s => s.WarehouseAllocations)
                .SingleOrDefault(s => s.WarehouseAllocations.Select(w => w.Id).Contains(warheouseAllocationId));

然后我对 Shipment 执行一些业务事件逻辑并保存所有更改。 (现在我可以用更好的方式来做)

我猜，如果您在保存更改之前进行包含受影响的实体类型的查询，Ef 会覆盖实体状态。