Page 18 of 22 - Chapter 14
Building Our Order Processing Page (cont'd)
If all has gone without error then we can start processing the order items.
We create the command object we will use to execute the AddOrderItem stored
procedure then we append the parameters.
// check if stored procedure executed ok
// abort transaction if failed
if (loCommand.Parameters("RV") != 0)
{
// get Stored Procs return VALUE
iErrorNo = loCommand.Parameters("RV");
ObjectContext.SetAbort;
}
else
{
// Retrieve CustId and OrderId from
// stored procs output variables
iCustId = loCommand.Parameters("CustId");
iOrderId = loCommand.Parameters("OrderId");
// Create new command object
// to add each order item detail to database
loCommand = null;
loCommand = Server.CreateObject("ADODB.Command");
loCommand.CommandText = "AddOrderItem";
loCommand.CommandType = adCmdStoredProc;
loCommand.Name = "AddOrderItem";
//Append Parameters @OrderId int, @ItemId int, @Qty int
loParam = loCommand.CreateParameter("RV", adInteger, _
adParamReturnValue);
loCommand.Parameters.Append(loParam);
loParam = loCommand.CreateParameter("OrderId", adInteger,
_
adParamInput,0,iOrderId);
loCommand.Parameters.Append(loParam);
loParam = loCommand.CreateParameter("ItemId", adInteger,
_
adParamInput);
loCommand.Parameters.Append(loParam);
loParam = loCommand.CreateParameter("Qty", adInteger,
_
adParamInput);
loCommand.Parameters.Append(loParam);
loCommand.ActiveConnection = loConn; |
Having created our Command object we can reuse it as we loop through the form
elements containing the ItemIds and quantities making up the order. After each
item has been added using the stored procedure we check that the return value
is zero indicating no errors. If there were errors then we call ObjectContext.SetAbort
and break out of the loop. Calling SetAbort will roll back all the order items
already added to the database as well as the customer and order details added
to the database. We are therefore assured that the database will not become
corrupted by half completed transactions.
Remember that a return value of 547 indicates an error due to insufficient
stock and we will write the code to handle that soon. If it's any other error
then the OnTransactionAbort event, which fires as a result of calling SetAbort,
will redirect the response to transerror.asp - a page we have yet to create.
Assuming that all has gone well, we call SetComplete to indicate the transaction's
success and to ensure the data gets committed to the database. The OnTransactionCommit
event fires and the customer is directed to a page confirming the transactions
success and e-mails both them and the order shipping department.
var sElementKey;
var iItemId;
var iQty;
// Loop through the item form elements
for (var iElementCounter = iItemElementStart; _
iElementCounter <= Request.Form.Count; iElementCounter++)
{
sElementKey = new String(Request.Form.Key(iElementCounter));
// if element NAME starts with ID its an item form element
if (sElementKey.substr(3,2) == "ID")
{
// Get ItemId from form VALUE passed
iItemId = parseInt _
(sElementKey.substring(5,sElementKey.length));
// move to next element which is quantity VALUE for that item
iElementCounter++;
// get quantity
iQty = parseInt(Request.Form(iElementCounter));
// set command's parameters
loCommand.Parameters("ItemId") = iItemId;
loCommand.Parameters("Qty") = iQty;
// execute stored procedure
loCommand.Execute();
// Any errors?
if (loCommand.Parameters("RV") != 0)
{
// set iErrorNo, abort transaction and break out of loop
iErrorNo = loCommand.Parameters("RV");
ObjectContext.SetAbort;
break;
}
}
}
}
// only set complete if transaction complete with no errors
if (iErrorNo == 0)
ObjectContext.SetComplete;
} |
Finally we come to the end of our order processing script and the catch part
of the try statement we set at the beginning of the code. If an error occurs
in our code, the statements here execute and we are able to store the description
in sErrorDescription and abort the transaction which will lead to the page being
redirected to transerror.asp by OnTransactionAbort.
catch(e)
{
sErrorDescription = e;
ObjectContext.SetAbort;
}
%> |
Save the page as ProcessOrder.asp.
