我需要提取与特定值(CourseCode
)对应的任意数量的记录,并将这些记录插入另一个表中。只要Linq
代码只返回一条记录,此代码就可以正常工作,但如果有更多,我会得到以下消息:
ObjectStateManager中已存在具有相同键的对象。 现有对象处于Modified状态。一个对象只能是 如果它在添加的对象中,则再次添加到ObjectStateManager。
以下是我的代码:
if (_db == null) _db = new AgentResourcesEntities();
var prodCodes = from records in _db.CourseToProduct
where records.CourseCode == course.CourseCode
select records;
foreach (var pt in prodCodes.ToList())
{
agentProdTraining.SymNumber = symNumber;
agentProdTraining.CourseCode = course.CourseCode;
agentProdTraining.ProductCode = pt.ProductCode;
agentProdTraining.DateTaken = course.DateTaken;
agentProdTraining.Method = course.Method;
agentProdTraining.LastChangeOperator = requestor;
agentProdTraining.LastChangeDate = DateTime.Now;
agentProdTraining.DateExpired = course.ExpirationDate;
agentProdTraining.ProductCode = pt.ProductCode;
agentProdTraining.NoteId = pt.NoteId;
_db.AgentProductTraining.AddObject(agentProdTraining);
_db.SaveChanges();
PtAdded++;
EventLog.WriteEntry(sSource, "Product Training added", EventLogEntryType.Warning);
}
答案 0 :(得分:4)
即使属性值发生更改,循环也会重新添加相同的agentProdTraining对象。为每个循环执行创建一个新实例。
foreach (var pt in prodCodes.ToList())
{
var agentProdTraining = new AgentProductTraining();
agentProdTraining.SymNumber = symNumber;
agentProdTraining.CourseCode = course.CourseCode;
agentProdTraining.ProductCode = pt.ProductCode;
agentProdTraining.DateTaken = course.DateTaken;
agentProdTraining.Method = course.Method;
agentProdTraining.LastChangeOperator = requestor;
agentProdTraining.LastChangeDate = DateTime.Now;
agentProdTraining.DateExpired = course.ExpirationDate;
agentProdTraining.ProductCode = pt.ProductCode;
agentProdTraining.NoteId = pt.NoteId;
_db.AgentProductTraining.AddObject(agentProdTraining);
_db.SaveChanges();
PtAdded++;
EventLog.WriteEntry(sSource, "Product Training added", EventLogEntryType.Warning);
}