Question

我首先在EF 5数据库中使用Attach添加/更新数据库中的行。

适用于数据库中尚不存在的实体。在尝试附加现有实体时，它会抛出异常An object with the same key already exists in the ObjectStateManager. The ObjectStateManager cannot track multiple objects with the same key.。

我已尝试过扩展，就像其他答案一样，没有人工作。

注意是我在没有设置PK的情况下附加了一个实体，我没有实现代码中的这些信息。

代码

var db = new XXX_DevEntities();
int YearMax = DateTime.Today.AddYears(5).Year;
var existent = (from a in db.BusinessDays
               where a.Year < YearMax
               select new { a.Year, a.Month }).ToList();
foreach (var aj in ajustes)
{
    for (int i = 1; i < 13; i++)
    {
        var entidade = new BusinessDays { Year = aj.Year, Month = i };
        db.BusinessDays.Attach(entidade);               // THROWS EXCEPTION HERE
        entidade.Qtd = aj.ValorMonth(i);
        db.Entry(entidade).State = existent.Contains(new { Year = aj.Year, Month = i }) ? EntityState.Modified : EntityState.Added;
    }
}

db.SaveChanges();

Answer 1

我发现了......

我选择了另一种方法，我通过从数据库中检索它（实际上是从数据库集的本地缓存中）来附加PK实体。

var db = new XXX_DevEntities();
int YearMax = DateTime.Today.AddYears(5).Year;
var existent = (from a in db.BusinessDays
               where a.Year < YearMax
               select a).ToList();
foreach (var aj in ajustes)
{
    for (int i = 1; i < 13; i++)
    {
        var codBusinessDay = diasUteisExistentes.Where(x => x.Year == aj.Year && x.Month == i).Select(x => x.CodBusinessDay).FirstOrDefault();
        var entidade = new BusinessDays { CodBusinessDay = codBusinessDay };
        db.BusinessDays.Attach(entidade);
        entidade.Year = aj.Year;
        entidade.Month = i;
        entidade.Qtd = aj.ValorMonth(i);
        db.Entry(entidade).State = codBusinessDay > 0 ? EntityState.Modified : EntityState.Added;
    }
}

db.SaveChanges();

附加空PK实体时，异常“无法跟踪具有相同键的多个对象”

1 个答案: