c# - 如何防止 Automapper 替换 Entity Framework 拥有的实体？

Question

我有两种类型。位置和位置有一个地址。地址指定为 owned entity使用

class LocationConfiguration : IEntityTypeConfiguration<Location>
{
    public void Configure(EntityTypeBuilder<Location> builder)
    {
        builder.HasKey(location => new { location.SubscriptionId, location.Id });
        builder.OwnsOne(location => location.Address);
    }
}

我正在获取现有位置实体并使用 Automapper 映射更新值。

[HttpPut("{subscriptionId}/{locationId}")]
public async Task<IActionResult> SaveLocationAsync(string subscriptionId, long locationId, [FromBody] Location location)
{
    if (location == null || location.Id != locationId || location.SubscriptionId != subscriptionId)
    {
        return BadRequest();
    }
    var dbLocation = await locations.GetLocationAsync(subscriptionId, locationId);
    if (dbLocation == null)
    {
        return NotFound();
    }
    mapper.Map<Location, Location>(location, dbLocation);
    return Ok(await locations.SaveAsync(dbLocation));
}

我通过调用 context.SaveChangesAsync(); 进行保存

但是我得到了错误

InvalidOperationException: The instance of entity type 'Location.Address#Address' cannot be tracked because another instance with the key value 'LocationSubscriptionId:123, LocationId:1' is already being tracked. When replacing owned entities modify the properties without changing the instance or detach the previous owned entity entry first.

我怀疑 Automapper 正在替换 Location 的 Address 属性，而不是向下导航并单独替换 Address 的属性。

有没有办法让 Automapper 更精细地复制属性值？

Answer 1

您应该使用 UseDestinationValue 在所有者类型映射配置中配置此类属性:

UseDestinationValue tells AutoMapper not to create a new object for some member, but to use the existing property of the destination object.

此外，如果您像示例中那样使用自映射，请确保为每个拥有的类型创建显式自映射。

对于您的示例，所需行为的最小 AutoMapper 配置如下:

cfg.CreateMap<Address, Address>();

cfg.CreateMap<Location, Location>()
    .ForMember(dest => dest.Address, opt => opt.UseDestinationValue());