如何使用实体框架更新具有外键引用的表？

Question

I have the following method:

public static Int32 SaveAgent(IAgent i)
    {
        dc = new mcollectorDataContext(ConnectionString.GetConStr());

       //check if the record exists
        t_agent matchID = dc.t_agents.Where(x => x.id == i.AgentID).FirstOrDefault();

        try
        {
            if (matchID == null)
            {
            // if not exists add new row
                t_agent _agent = new t_agent
                {
                    wallet = i.Wallet,
                    branchid = GetBranchID(i.Branch),
                    lastupdated = i.LastUpdated,
                };
                   dc.t_agents.InsertOnSubmit(_agent);
                   dc.SubmitChanges();
                   return _agent.id;
            }
            else
            {
                // else update row
                matchID.wallet = i.Wallet;
                matchID.branchid = GetBranchID(i.Branch);
                matchID.lastupdated = i.LastUpdated;

                dc.SubmitChanges();
                return i.AgentID;
            }

        }
        catch (Exception)
        {
            throw ;
        }
    }

This method save new reord but when i try to update, it failed, no record can be updated, but it does not throw also an error. How can fix that problem ??

Answer 1

maybe try telling entity framework that the model has been modified?

try adding this before calling submitchanges

dc.Entry(matchID).State = EntityState.Modified;