Triggers cause .Insert to return incorrect Id, @@identity vs scope_identity() about dapper.simplecrud

[chrishylton]

I tried one solution, seem to work well but definitely a kludge just using a try/catch (ick) where it tries using scope_identity() first, and if a parsing error occurs then it retries with @@identity.

    public static int Insert(this IDbConnection connection, object entityToInsert, IDbTransaction transaction = null, int? commandTimeout = null)
    {
        var name = GetTableName(entityToInsert);

        var sb = new StringBuilder();
        sb.AppendFormat("insert into [{0}]", name);
        sb.Append(" (");
        BuildInsertParameters(entityToInsert, sb);
        sb.Append(") values (");
        BuildInsertValues(entityToInsert, sb);
        sb.Append("); select cast(scope_identity() as int)");

        if (Debugger.IsAttached)
            Trace.WriteLine(String.Format("Insert: {0}", sb));

        try
        {
            var newId = connection.Query<int?>(sb.ToString(), entityToInsert).Single();
            return (newId == null) ? 0 : (int)newId;               
        }
        catch (Exception e)
        {
            if (e.Message.ToLower().StartsWith("there was an error parsing"))
            {
                sb = new StringBuilder();
                sb.AppendFormat("insert into [{0}]", name);
                sb.Append(" (");
                BuildInsertParameters(entityToInsert, sb);
                sb.Append(") values (");
                BuildInsertValues(entityToInsert, sb);
                sb.Append(");");

                if (Debugger.IsAttached)
                    Trace.WriteLine(String.Format("Insert: {0}", sb));

                connection.Execute(sb.ToString(), entityToInsert, transaction, commandTimeout);
                var r = connection.Query("select @@identity id", null, transaction, true, commandTimeout);
                return (int)r.First().id;
            }
            else
            {
                throw e;
            }
        }
    }

[ericdc1]

Considering this. If anyone has a good idea on how to best handle this please comment.

[chrishylton]

Cool. It'd be nice to have something returning the appropriate identity. By 'considering this', hope you don't mean my goofy solution above. It's not a solution, just something to exhibit the problem and was just a quick cut-n-paste to get something working. I ultimately decided NOT to maintain a custom SimpleCRUD project and I ended up dealing with it manually, going back to the DB on inserts using a unique index to get the identity/pk on the record. The error "there was an error parsing" could come back for a whole pile of reasons. Has to be a better way, and avoid my redundancy in the code above. Ugh. I'll give this more thought...

[ericdc1]

With the latest version, SQL Server uses scope_identity, and SQLCE uses @@Identity which should solve this problem.

[chrishylton]

Thanks for the update to the code, will definitely make use of this feature by removing additional trips back to the DB now. Excellent !