
Dynamic expressions and dynamic variables
99
<cfif i mod 2 EQ 0>
<cfset Color = "white">
<cfelse>
<cfset Color = "gray">
</cfif>
<tr bgcolor="#color#">
<td>
hello #i#
</td>
</tr>
</cfloop>
</table>
</cfoutput>
Example: a dynamic shopping cart
The following example dynamically creates and manipulates variable names without using
dynamic expression evaluation by using associative array notation.
You need to dynamically generate variable names in applications such as shopping carts, where
the required output is dynamically generated and variable. In a shopping cart, you do not know in
advance the number of cart entries or their contents. Also, because you are using a form, the
action page only receives Form variables with the names and values of the form fields.
The following example shows the shopping cart contents and lets you edit your order and submit
it. To simplify things, the example automatically generates the shopping cart contents using
CFScript instead of having the user fill the cart. A more complete example would populate a
shopping cart as the user selected items. Similarly, the example omits all business logic for
committing and making the order.
To create the form:
1
Create a file in your editor.
<html>
<head>
<title>Shopping Cart</title>
</head>
<cfscript>
CartItems=4;
Cart = ArrayNew(1);
for ( i=1; i LE cartItems; i=i+1)
{
Cart[i]=StructNew();
Cart[i].ID=i;
Cart[i].Name="Product " & i;
Cart[i].SKU=i*100+(2*i*10)+(3*i);
Cart[i].Qty=3*i-2;
}
</cfscript>
<body>
Your shopping cart has the following items.<br>
You can change your order quantities.<br>
If you don't want any item, clear the item's check box.<br>
When you are ready to order, click submit.<br>
<br>
<cfform name="ShoppingCart" action="ShoppingCartAction.cfm" method="post">
<table>
<tr>
Summary of Contents for COLDFUSION MX 61-DEVELOPING COLDFUSION MX
Page 1: ...Developing ColdFusion MX Applications...
Page 22: ...22 Contents...
Page 38: ......
Page 52: ...52 Chapter 2 Elements of CFML...
Page 162: ......
Page 218: ...218 Chapter 10 Writing and Calling User Defined Functions...
Page 250: ...250 Chapter 11 Building and Using ColdFusion Components...
Page 264: ...264 Chapter 12 Building Custom CFXAPI Tags...
Page 266: ......
Page 314: ...314 Chapter 14 Handling Errors...
Page 344: ...344 Chapter 15 Using Persistent Data and Locking...
Page 349: ...About user security 349...
Page 357: ...Security scenarios 357...
Page 370: ...370 Chapter 16 Securing Applications...
Page 388: ...388 Chapter 17 Developing Globalized Applications...
Page 408: ...408 Chapter 18 Debugging and Troubleshooting Applications...
Page 410: ......
Page 426: ...426 Chapter 19 Introduction to Databases and SQL...
Page 476: ...476 Chapter 22 Using Query of Queries...
Page 534: ...534 Chapter 24 Building a Search Interface...
Page 556: ...556 Chapter 25 Using Verity Search Expressions...
Page 558: ......
Page 582: ...582 Chapter 26 Retrieving and Formatting Data...
Page 668: ......
Page 734: ...734 Chapter 32 Using Web Services...
Page 760: ...760 Chapter 33 Integrating J2EE and Java Elements in CFML Applications...
Page 786: ...786 Chapter 34 Integrating COM and CORBA Objects in CFML Applications...
Page 788: ......