The underlying provider failed on open

Question

Hi all,
I use the following Save method for the context so that I first insert the entities so that I have their identity column, then save the audit log for them.
public int Save()
int recordsUpdated = 0;
List<History> historyList = new List<History>();
this.DetectChanges();
IEnumerable<ObjectStateEntry> list = this.ObjectStateManager.GetObjectStateEntries(EntityState.Added | EntityState.Deleted | EntityState.Modified);
foreach (var ent in list)
if (!ent.IsRelationship && ent.Entity != null && !(ent.Entity is History))
historyList.Add(new History(ent));
DbConnection conn = ((EntityConnection)this.Connection).StoreConnection;
ConnectionState initialState = conn.State;
try
//Open connection if not already open
if (initialState != ConnectionState.Open)
conn.Open();
using (var scope = new TransactionScope())
recordsUpdated = this.SaveChanges();
if (historyList.Count > 0)
foreach (var history in historyList)
history.SetDetails();
this.Histories.AddObject(history);
this.SaveChanges();
catch (Exception ex)
System.Diagnostics.Debug.WriteLine(ex);
finally
//Only close connection if not initially open
if (initialState != ConnectionState.Open)
conn.Close();
return recordsUpdated;
The first thing to notice is that the connection is closed that's why I'm opening it.
First problem:
When updating an existing record and I reach the second call to SaveChanges, I get the above exception.
Second problem:
When inserting an new record I get the following exception:
"An error occurred while updating the entries. See the inner exception for details."}
    [System.Data.UpdateException]: {"An error occurred while updating the entries. See the inner exception for details."}
    Data: {System.Collections.ListDictionaryInternal}
    HelpLink: null
    HResult: -2146233087
    InnerException: {"The member with identity '' does not exist in the metadata collection.\r\nParameter name: identity"}
    Message: "An error occurred while updating the entries. See the inner exception for details."
    Source: "System.Data.Entity"
    StackTrace: "   at System.Data.Mapping.Update.Internal.UpdateTranslator.Update(IEntityStateManager stateManager, IEntityAdapter adapter)\r\n   at System.Data.EntityClient.EntityAdapter.Update(IEntityStateManager entityCache)\r\n  
at System.Data.Objects.ObjectContext.SaveChanges(SaveOptions options)\r\n   at System.Data.Objects.ObjectContext.SaveChanges()\r\n   at AboServer.AboSystem5DB.Save() in C:\\Development\\dotNET\\ABOSystem5\\Server\\Common\\AboSystem5DB.cs:line
136"
    TargetSite: {Int32 Update(System.Data.IEntityStateManager, System.Data.IEntityAdapter)}
Need help!!

Answer 1

Couple of things:
1) When using Entity Framework, you do not need to explicitly open the connection.  This statement should do it for you.  Not only does it open the connection it also closes it when going out of scope of the USING verb.
using (var scope = new TransactionScope())
2) This part of the stack trace---> System.Data.Mapping.Update.Internal.UpdateTranslator.Update
    Tells me that something is wrong with Mapping.  I personally do not manually attempt to map anything when using EF because it appeared to be complex and required a lot of study of which I didn't have the time.  So...I always
allow EF to create the tables and mappings and it works everytime.
I'd suggest removing the explicit open code and fall back to the Using statement only.  I'd also suggest recreating your table model using EF's wizard which forces you to do the connection string and then to pick the proper tables.  It knows how
to map everything and does a great job of it.
JP Cowboy Coders Unite!