Redirect to PayPal upon clicking the Submit button

Question

Hi Vulpes

Sorry to email you direct I have posted an advert on the forum but havent had a reply and I know your be able to answer this no problems.

Ive written Submit and GetTotal methods as follows:-

public decimal GetTotal(string cartID)

{

using (DCECommerceDBEntities db = new DCECommerceDBEntities())

{

decimal cartTotal = 0;

try

{

var mycart = (from c in db.ViewCarts where c.CartID == cartID select c);

if (mycart.Count() > 0)

{

cartTotal = mycart.Sum(od => (decimal)od.Quantity * (decimal)od.UnitCost);

}

catch (Exception exp)

{

throw new Exception("ERROR: Unable to Calculate Order Total - " + exp.Message.ToString(), exp);

}

return (cartTotal);

}

public bool SubmitOrder(string userName)

{

using (DCECommerceDBEntities db = new DCECommerceDBEntities())

{

try

{

Order newOrder = new Order();

newOrder.CustomerName = userName;

newOrder.OrderDate = DateTime.Now;

db.Orders.AddObject(newOrder);

db.SaveChanges();

int NewOrderKey = (from p in db.Orders select p.OrderID).Max();

String cartId = GetShoppingCartId();

var myCart = (from c in db.ViewCarts where c.CartID == cartId select c);

foreach (ViewCart item in myCart)

{

OrderDetail od = new OrderDetail();

od.OrderID = NewOrderKey;

od.ProductID = item.ProductID;

od.Quantity = item.Quantity;

od.UnitCost = item.UnitCost;

db.OrderDetails.AddObject(od);

var myItem = (from c in db.ShoppingCarts where c.CartID == item.CartID && c.ProductID == item.ProductID select c).FirstOrDefault();

if (myItem != null)

{

db.DeleteObject(myItem);

}

db.SaveChanges();

}

catch(Exception exp)

{

}

return true;

}

I basically want to implement the below so that I can pass the return values ie orderId etc to PayPal.

string redirect = "";

redirect += "https://www.paypal.com/xclick/[email protected]";

redirect += "&item_name=" + siteName + " Order " + orderId;

redirect += "&item_number=" + orderId;

redirect += "&amount=" + String.Format("{0:0.00} ", amount);

redirect += "&currency=USD";

redirect += "&return=http://www." + siteName + ".com";

redirect += "&cancel_return=http://www." + siteName + ".com";

// Redirect to the payment page

Response.Redirect(redirect);

With regards to the siteName I can use a const string so thats fine and the currency is easily enough also, its mainly the Total Amount and OrderId I need help with please.

Many thanks

Steven

Vulpes · Answer

Sure here's an example using the earlier code: public int SubmitOrder(string userName  out List orderDetails ) { int NewOrderKey = -1; using (DCECommerceDBEntities db = new DCECommerceDBEntities()) { try { Order newOrder = new Order(); newOrder.CustomerName = userName; newOrder.OrderDate = DateTime.Now; db.Orders.AddObject(newOrder); db.SaveChanges(); NewOrderKey = (from p in db.Orders select p.OrderID).Max(); String cartId = GetShoppingCartId(); var myCart = (from c in db.ViewCarts where c.CartID == cartId select c); orderDetails = new List (); foreach (ViewCart item in myCart) { OrderDetail od = new OrderDetail(); od.OrderID = NewOrderKey; od.ProductID = item.ProductID; od.Quantity = item.Quantity; od.UnitCost = item.UnitCost; orderDetails.Add(od); db.OrderDetails.AddObject(od); var myItem = (from c in db.ShoppingCarts where c.CartID == item.CartID && c.ProductID == item.ProductID select c).FirstOrDefault(); if (myItem != null) { db.DeleteObject(myItem); } } db.SaveChanges(); } catch(Exception exp) { } } return NewOrderKey; } You can then do: List orderDetails; int orderId = SubmitOrder(userName  out orderDetails ); if (orderId > -1) { // iterate through your orderDetails list foreach(OrderDetail od in orderDetails) { int quantity = od.Quantity; // do something with quantity } // assemble your redirect string } else { // something went wrong } You'll need to be careful not to alter any of the OrderDetails objects otherwise the changes will be persisted to the database the next time SaveChanges is called. However just reading the values of the properties should be no problem.

S · Answer

A million thanks Vulpes your time help and patience once again is hugely appreciated! Thank-you!

Vulpes · Answer

It looks OK except that the second argument to the SubmitOrder method needs to be preceded by 'out': usersShoppingCart.SubmitOrder(User.Identity.Name out orderDetails);

S · Answer

I just need to get the Quantity for each item in the ShoppingCart which is persisted to the OrderDetail table in the DB via the SubmitOrder method. Yes im using .NET 4.0 VS 2010. Ive now added my DataAccess folder containing the EF to the CheckOut class. Now within my Submit button Event Handler of the CheckOut class it looks like this:- List orderDetails // Local variable to hold output usersShoppingCart.SubmitOrder(User.Identity.Name orderDetails); foreach(OrderDetail od in orderDetails) { int quantity = od.Quantity; // do something with Quantity (ie pass the Quantity value to PayPal!) } Does this look right to you? Thanks Steven

Vulpes · Answer

What do you actually need apart from the Quantity property and are you using .NET 4.0 or an earlier version?

S · Answer

Hi Vulpes Unfortunately I cant get that to work. Basically I need to use the below code in a different class being the CheckOut class. I currently access the SubmitOrder method like so:- reference.SubmitOrder(User.Identity.Name); Which works fine But now ive modified SubmitOrder to provide an out parameter the List orderDetails doesnt exist in the CheckOut class... The CheckOut class is where I pass the values to PayPal. I guess I could just put my using statement in the CheckOut class to get access to the EF objects enabling me to use the out parameter in the the CheckOut class? however this would be a New object and not the current object im working with. Thanks Steven You can then do: List orderDetails; int orderId = SubmitOrder(userName out orderDetails); if (orderId > -1) { // iterate through your orderDetails list foreach(OrderDetail od in orderDetails) { int quantity = od.Quantity; // do something with quantity } // assemble your redirect string } else { // something went wrong }

Vulpes · Answer

That line is just an example of how to get the Quantity property for a particular OrderDetail object. The important thing is that you can iterate through all the OrderDetail objects using foreach access the Quantity property (and any other properties you need) for each object in turn and do what you like with them.

S · Answer

Hi Vulpes Sorry to be a pain Just reading through your code sample you kindly provided could you explain this please // iterate through your orderDetails list foreach(OrderDetail od in orderDetails) { int quantity = od.Quantity; // do something with quantity } Is... int quantity = od.Quantity getting all the Quantities? or just the last ones entered into the OrderDetail table? Thanks Steven

S · Answer

Brilliant thank you very much Vulpes I understand perfectly : ) Regards Steven

S · Answer

Yeah that sounds like the best bet Vulpes thanks. So I guess I just need to Prefix the List onto the existing OrderDetail ie List ? How could I then use the out parameter to get the required Quantities could you provide a sample please?

Vulpes · Answer

That's no problem as you can use an out parameter of type List . But do you just want the quantities themselves or do you need further information such as the product type? Perhaps it would be easier just to return a List of all the OrderDetail objects and you could then pick out any info you wanted.

S · Answer

Good question the reason I need the information is so that it can be passed to PayPal for payment therefore if there were 1 item in the cart with a quantity of 1 id like this quantity. If there were 2 items in the cart and 1 had a quantity of 1 and the other item had a quantity of 1 id like both the 1 quantites if that makes sense? if this is too tricky it doesnt matter. Thanks!

Vulpes · Answer

The usual way to get a second return value out of a method is to use an 'out' parameter. This would be quicker and easier than using a database query. However there are a number of 'Quantities' generated within the SubmitOrder method - one for each item in the cart. So are you trying to get the last one generated or all of them?

S · Answer

Vulpes If I needed to get another return value out of the SubmitOrder method ie Quantity in addition to the OrderId how would you say id go about this? I guess the other way would be to write a Query to retrieve the last entered info into the OrderDetail table of the database? Regards Steven

Vulpes · Answer

You can't convert from int to bool in C# but you can test to see whether the return value of the SubmitOrder method is greater than -1 or not. Remember that -1 is the value which we're using to denote failure: if(usersShoppingCart.SubmitOrder(User.Identity.Name) > -1); { PaymentButton.Visible = true; // Show or Display the Payment button }

S · Answer

Hi Vulpes As ive now changed the return type of SubmitOrder from bool to int. I ideally want to do a cast from int to bool in order to return a true or false as to whether the submission was successful or not. Once the result is rec'd I wish to go on and do something else. for example given:- if(usersShoppingCart.SubmitOrder(User.Identity.Name) == true); { PaymentButton.Visable = true; // Show or Display the Payment button } At the moment the SubmitOrder method is of Return Type int so a conversion error obviously occurs. Therefore I want to do something like this:- if((bool)usersShoppingCart.SubmitOrder(User.Identity.Name) == true); { PaymentButton.Visable = true; // Show or Display the Payment button } but this does'nt work!? Any help appreciated. Regards steven

S · Answer

Simply an oversight on my part Vulpes it works fine many thanks! Regards Steven

Vulpes · Answer

I don't understand that as NewOrderKey should be in scope throughout the SubmitOrder method. Can you pinpoint on which line the error occurs ?

Vulpes · Answer

Well you could place this code at the end of the SubmitOrder method and then change the return type back to bool from int: decimal amount = 0; try { amount = GetTotal(cartId); } catch(Exception ex) { // do something about not being able to calculate order total return false; } if(NewOrderKey > -1) { // Redirect string return true; } else { // Something went wrong return false; }

S · Answer

Thanks again Vulpes. Would you say its best to isolate\encapsulate the 2 method calls ie decimal amount = GetTotal(cartId); int orderId = SubmitOrder(userName); if(orderId > -1) { // R edirect string } else { // Something went wrong } into a method of its own and then place the method at the end of the SubmitOrder method once all the operations\actions have been completed? Thanks Steve

Vulpes · Answer

As you're no longer using bool it's useful to have a return value which can indicate that some failure has taken place. The alternative would be to throw an exception within the method but I personally don't like doing that unless it's absolutely necessary. I thought -1 would be a suitable value for this as your OrderIds are not going to be negative numbers.

S · Answer

Many thanks indeed Vulpes. I can see what you've done there regards to refactoring so that the OrderId can be retrieved easily however could you explain the reason for setting NewOrderKey to -1 please? Regards Steven

Vulpes · Answer

Well as far as the total amount is concerned it should just be a matter of calling your GetTotal method and then assigning the result to your 'amount' variable: decimal amount = GetTotal(cartId); As far as the orderId is concerned it would be better if your SubmitOrder were to return this rather than a bool: public int SubmitOrder(string userName) { int NewOrderKey = -1; using (DCECommerceDBEntities db = new DCECommerceDBEntities()) { try { Order newOrder = new Order(); newOrder.CustomerName = userName; newOrder.OrderDate = DateTime.Now; db.Orders.AddObject(newOrder); db.SaveChanges(); NewOrderKey = (from p in db.Orders select p.OrderID).Max(); String cartId = GetShoppingCartId(); var myCart = (from c in db.ViewCarts where c.CartID == cartId select c); foreach (ViewCart item in myCart) { OrderDetail od = new OrderDetail(); od.OrderID = NewOrderKey; od.ProductID = item.ProductID; od.Quantity = item.Quantity; od.UnitCost = item.UnitCost; db.OrderDetails.AddObject(od); var myItem = (from c in db.ShoppingCarts where c.CartID == item.CartID && c.ProductID == item.ProductID select c).FirstOrDefault(); if (myItem != null) { db.DeleteObject(myItem); } } db.SaveChanges(); } catch(Exception exp) { } } return NewOrderKey; } You can then do: int orderId = SubmitOrder(userName); if (orderId > -1) { // assemble your redirect string } else { // something went wrong }