如何在EntityFramework 6中更新带有子细节的父对象?

本文关键字：细节对象 EntityFramework 更新 | 更新日期: 2023-09-27 18:01:39

我有一个SPA ASP。. NET WebAPI应用程序，使用EF6。应用程序有两个父子实体，我在更新时遇到了问题。代码的目的是，当用户更改前端代码时，目标及其详细信息将被发送到控制器。然后，控制器检查是否有任何细节发生了变化，并对其进行处理。现在我已经注释了这部分代码，因为我甚至不能得到最简单的更新工作。下面是我得到的错误:

{"附加类型为'Entities.Models.Core.ObjectiveDetail'的实体失败，因为另一个相同类型的实体已经有相同的主键值。这可能发生在使用'Attach'方法或将实体的状态设置为"未更改"或"修改"(如果有)图中的实体具有冲突的键值。这可能是因为有些实体是新的，尚未收到数据库生成键值。在这种情况下，使用'Add'方法或'Added'实体状态来跟踪图形，然后将非新实体的状态设置为"未修改"或"修改"视情况而定。"}

我有两个类:

public class Objective
{
    public Objective()
    {
        this.ObjectiveDetails = new HashSet<ObjectiveDetail>();
    }
    public int ObjectiveId { get; set; }
    public string Text { get; set; }
    public virtual ICollection<ObjectiveDetail> ObjectiveDetails { get; set; }
}
public partial class ObjectiveDetail
{
    public int ObjectiveDetailId { get; set; }
    public int ObjectiveId { get; set; }
    public string Text { get; set; }
    public virtual Objective Objective { get; set; }
}

我的控制器是这样的:

    // PUT: api/Objective/5 Updating
    [ResponseType(typeof(void))]
    public async Task<IHttpActionResult> Put(int id, Objective objective)
    {
        try
        {
            // I get an exception when I uncomment the following line
            //
            //
            // var oldObj = db.ObjectiveDetails.Where(t => t.ObjectiveId == id).ToList();
            var newObj = objective.ObjectiveDetails.ToList();
            //var upd = newObj
            //    .Where(wb => oldObj
            //    .Any(db1 =>
            //       (db1.ObjectiveDetailId == wb.ObjectiveDetailId) &&
            //           (db1.Number != wb.Number || !db1.Text.Equals(wb.Text))))
            //           .ToList();
            //var add = newObj
            //    .Where(wb => oldObj
            //        .All(db2 => db2.ObjectiveDetailId != wb.ObjectiveDetailId))
            //    .ToList();
            //var del = oldObj
            //    .Where(db2 => newObj
            //        .All(wb => wb.ObjectiveDetailId != db2.ObjectiveDetailId))
            //    .ToList();
            //foreach (var objectiveDetail in upd)
            //{
            //    db.Entry(objectiveDetail).State = EntityState.Modified;
            //}
            //foreach (var objectiveDetail in add)
            //{
            //    db.ObjectiveDetails.Add(objectiveDetail);
            //}
            //del.ForEach(_obj => db.ObjectiveDetails.Remove(_obj));
            // I tried the following but it did not work
            //
            //db.Objectives.Attach(objective);
            //db.Entry(objective).State = EntityState.Modified;
            DbEntityEntry dbEntityEntry = db.Entry(objective);
            if (dbEntityEntry.State == EntityState.Detached)
            {
                db.Objectives.Attach(objective);
            }
            dbEntityEntry.State = EntityState.Modified;
            await db.SaveChangesAsync();
            return Ok(objective);
        }
        catch (Exception e)
        {
            return NotFound();
        }
    }