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Page 17 of 22 - Chapter 14
Building our Order Processing Page
OK, now let's make a start on creating ProcessOrder.asp
At the very top of the page are two pre-processor directives, the first stating
that this page requires a new transaction, the second making the default language
JScript. We need to explicitly state we want this to be a transaction-based
page by using the TRANSACTION pre-processor directive.
| <%@ TRANSACTION=Requires_New Language="JScript"
%> |
Next we define some page level variables and set the page to buffer which
means no response will be sent to the client browser until we reach the end
of the page or we explicitly say so. This allows us to redirect the response
in mid flow.
Event code has been written for OnTransactionAbort and OnTransactionCommit.
OnTransactionAbort checks the error number and if it's not 547 - indicating
an error of insufficient stock - then the response is redirected to the transerror.asp
page which lists the error cause. OnTransactionCommit clears the basket cookie,
then redirects to the acceptOrder.asp page which displays a success message
and e-mails the customer and the shipping department who actually sends the
goods.
<%
Response.Buffer = true;
// Database connection string
var sdbConnString = "Provider=SQLOLEDB.1;Password=madforit; _
Persist Security Info=True;User ID=MMCustomer;
_
Initial Catalog=MusicMad;Data Source=.";
var iErrorNo = 0;
var sErrorDescription;
// Index of first Item element in form
var iItemElementStart = 1;
// ADO constants make code more readable
var adCmdStoredProc = 4;
var adParamReturnValue = 4;
var adParamInput = 1;
var adParamOutput = 2;
var adVarChar = 200;
var adInteger = 3;
function OnTransactionAbort()
{
// If error is not insufficent stock
if (iErrorNo != 547)
{
Response.Redirect("transerror.asp?" + escape(sErrorDescription));
}
}
function OnTransactionCommit()
{
// Everything went ok - re-direct to confirmation page
Response.Cookies("Basket")= "";
Response.Redirect("acceptorder.asp?" + iOrderId);
} |
Now we open up a connection to the database and create a command object which
we will use to execute our stored procedure NewOrder. NewOrder will add the
customer and credit card details to the database.
Note the whole of the transaction code is inside a JScript 5.0 try.catch clause.
If any other non-database errors occur we can catch them and ensure the transaction
is aborted.
// Process order form
try
{
var loConn = Server.CreateObject("ADODB.Connection");
var loCommand = Server.CreateObject("ADODB.Command");
var loParam;
var iCustId = -1;
var iOrderId = -1;
loConn.Open(sdbConnString);
// Create ADO command object which will execute our stored procedure
loCommand.CommandText = "NewOrder";
loCommand.CommandType = adCmdStoredProc;
loCommand.Name = "NewOrder"; |
Before we can execute the ADO Command we need to append the parameters the stored
procedure expects and this is the task of the next piece of code.
There are a lot of parameters to append but the method is the same for each.
-
First a new parameter object is created using the ADO command object's CreateParameter
method whose arguments are parameter name, parameter type, direction, size
and default value.
-
Then the new parameter is appended to the Command object using the Append
method.
The first parameter we define is the return value which is an integer. If a
return value is expected then it must always be the first parameter appended.
Here the return value is used to notify us of any errors that occurred inside
the stored procedure. The remaining parameters except for the last two are input
parameters used to pass values to the stored procedure. The final two parameters
are output parameters which the stored procedure populates with the CustId of
the customer row added to the database and OrderId of the order.
// @Title, @FirstName varchar(50), @LastName
varchar(50),
// @Email varchar(75), @Street varchar(75)
loParam = loCommand.CreateParameter("RV",adInteger, _
adParamReturnValue);
loCommand.Parameters.Append(loParam);
loParam = loCommand.CreateParameter("Title",adVarChar,adParamInput,
_
4, Request.Form("txtTitle"));
loCommand.Parameters.Append(loParam);
loParam = loCommand.CreateParameter("FirstName", adVarChar,
_
adParamInput, 50, _
Request.Form("txtFirstName"));
loCommand.Parameters.Append(loParam);
loParam = loCommand.CreateParameter("LastName", adVarChar,
_
adParamInput, 50, _
Request.Form("txtLastName"));
loCommand.Parameters.Append(loParam);
loParam = loCommand.CreateParameter("Email", adVarChar, adParamInput,_
75, Request.Form("txtEmail"));
loCommand.Parameters.Append(loParam);
loParam = loCommand.CreateParameter("Street", adVarChar,
adParamInput,
75, Request.Form("txtStreet"));
loCommand.Parameters.Append(loParam);
//@City varchar(50), @Locality varchar(50), @Country varchar(50)
loParam = loCommand.CreateParameter("City", adVarChar, adParamInput,
_
50, Request.Form("txtCity"));
loCommand.Parameters.Append(loParam);
loParam = loCommand.CreateParameter("Locality", adVarChar,
_
adParamInput, 50, _
Request.Form("txtLocality"));
loCommand.Parameters.Append(loParam);
loParam = loCommand.CreateParameter("PostCode", adVarChar,
_
adParamInput, 15, _
Request.Form("txtPostCode"));
loCommand.Parameters.Append(loParam);
loParam = loCommand.CreateParameter("Country", adVarChar,
_
adParamInput, 50, _
Request.Form("txtCountry"));
loCommand.Parameters.Append(loParam);
// @CCHolderName varchar(50), @CCType varchar(25),
// @CCNo varchar(20), @CCExpire varchar(7)
loParam = loCommand.CreateParameter("CCHolderName", adVarChar,
_
adParamInput, 50, _
Request.Form("txtCCHolderName"));
loCommand.Parameters.Append(loParam);
loParam = loCommand.CreateParameter("CCType", adVarChar,
adParamInput,
25, Request.Form("txtCCType"));
loCommand.Parameters.Append(loParam);
loParam = loCommand.CreateParameter("CCNo", adVarChar, adParamInput,
_
20, Request.Form("txtCCNo"));
loCommand.Parameters.Append(loParam);
loParam = loCommand.CreateParameter("CCExpire", adVarChar,
_
adParamInput, 7, _
Request.Form("txtCCExpire"));
loCommand.Parameters.Append(loParam);
// @CustId int, @OrderId int
loParam = loCommand.CreateParameter("CustId", adInteger,
_
adParamOutput);
loCommand.Parameters.Append(loParam);
loParam = loCommand.CreateParameter("OrderId", adInteger,
_
adParamOutput);
loCommand.Parameters.Append(loParam); |
The Command's connection is set to the ADO Connection we opened and the Command
is executed.
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loCommand.ActiveConnection = loConn;
loCommand.Execute();
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If there were any problems with the stored procedure's execution, its return
value will not be zero and we need to abort this transaction. Calling ObjectContext.SetAbort
will abort the transaction and cause OnTransactionAbort to fire and run any
'clean-up code' we put there. In our case this is where we redirect the user
to the transerror.asp page.
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