an endless loop of Csharp.Frustration[s]

Date: 11/22/07 (Web Development) Keywords: database, asp, security, web, shopping

Hi all,

I'll write my C# frustrations here...Note that this is for an assignment, so there is no need to worry about security issues and all those other wonderful things. I would ask my professor, but he's a programmer...and he's horrible at getting his thoughts across.

I created a web form that allows users to choose a certain amount of a product they want, and afterwards, it all gets confirmed and a message shows up saying the conversion was completed (even though it wasn't...not yet anyway)

Please note that I am NOT looking for code answers just to copy and paste. I would like the theory of how I should go about solving this - since most websites just give you a basic understanding of how try/catch works.

Problem 1: How do I implement the "try", "catch", "finally" exception if a user picks the same product and quantity twice? I already have an if-statement that keeps track of what has been chosen in the user's session. Would the try/catch go into that if-statement?

Problem 2: What if the user decides to first order 3 items of a product, then decides to order more? How would I input this into the "try", "catch", "finally"? I have an if-statement that keeps track of whether the quantity has been "trimmed" or not.

Problem 3: Do I need a database connection command in that particular web page to determine how much of a product has been chosen and how much is available to other users?

Problem 4: Confirmation e-mail. I understand the whole idea of "using System.Net;" for email, but how would I go about implementing code to get an e-mail application started? (This problem/question is seperate from the code below)

Here's my code for the different problems 1 - 3:

protected void btnOrder_Click(object sender, EventArgs e)
{
//Check for Shoppingcart object
// Create first if not there

if (Session["cart"] == null)
{
Session["cart"] = new ShoppingCart();
int quantity = 0;
}

// make sure there is text
if (txtQuantity.Text.Trim().Length != 0)
{
// try to convert text to int ???
int quantity = int.Parse(txtQuantity.Text);
// check for this item in the cart
// Note this only makes sense if the "cart" exists
// since it checks for an individual item in the cart
if (((ShoppingCart)Session["cart"]).
keyExists(int.Parse(TextBox1.Text)))
{
//throw new Exception("Item already in cart - fix this");

Response.Write("Item already exists in cart. What do you want to do?");
// Message to user that product is already in the order

///AND this is where my problems start:
/*try
{

Response.Write("Item already exists, what do you want to do?");
}

catch (ArgumentException de)
{
ShoppingCart;
}

finally
{
Console.WriteLine("Finally Block");
}
* */
///END of one set of problems (sorry for intending issues)

}
if ((txtQuantity.Text.Trim().Length != 0)) // This is a new item
{
//Response.Write("Please choose the quantity");
OrderItem item = new OrderItem(
int.Parse(TextBox1.Text), TextBox2.Text,
double.Parse(TextBox6.Text),
int.Parse(txtQuantity.Text));
((ShoppingCart)Session["cart"]).addToCart(item);
Response.Write("Item added successfully!");
Server.Transfer("CatalogDisplay.aspx");

}
else
{
// Make the item
OrderItem item = new OrderItem(
int.Parse(TextBox1.Text), TextBox2.Text,
double.Parse(TextBox6.Text),
int.Parse(txtQuantity.Text));
// add to cart
((ShoppingCart)Session["cart"]).addToCart(item);

///////////////////////////////not sure what the next part does

// How to make this work ??
// Who is the sender ?
// What are the System.EventArgs ?
this.btnReturn_Click(sender, e);

//////////end of "not sure"
}
else
{
//Basically if the quantity field is empty, you can't move on to the Order page.
Response.Write("Nothing Ordered
You must order some of the product or return to the Catalog");
}

Source: http://community.livejournal.com/webdev/449890.html

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