make sure that SetValue is the last thing to happen when there is a type-handler

Dapper NET40/SqlMapper.cs

@@ -4002,14 +4002,15 @@ protected void AddParameters(IDbCommand command, SqlMapper.Identity identity)
                     {
                         p = (IDbDataParameter)command.Parameters[name];
                     }
+
+                    p.Direction = param.ParameterDirection;
                     if (handler == null)
                     {
                         p.Value = val ?? DBNull.Value;
-                    } else
+                        if (dbType != null && p.DbType != dbType)
                         {
-                        handler.SetValue(p, val ?? DBNull.Value);
+                            p.DbType = dbType.Value;
                         }
-                    p.Direction = param.ParameterDirection;
                         var s = val as string;
                         if (s != null)
                         {
@@ -4022,10 +4023,14 @@ protected void AddParameters(IDbCommand command, SqlMapper.Identity identity)
                         {
                             p.Size = param.Size.Value;
                         }                        
-                    if (dbType != null && p.DbType != dbType)
+                    }
+                    else
                     {
-                        p.DbType = dbType.Value;
+                        if (dbType != null) p.DbType = dbType.Value;
+                        if (param.Size != null) p.Size = param.Size.Value;
+                        handler.SetValue(p, val ?? DBNull.Value);
                     }
+
                     if (add)
                     {
                         command.Parameters.Add(p);