Sent: Friday, October 03, 2003 12:45
PM
Subject: RE: [CFCDev] Just starting
CFC's -- Session Question
Yes --
basically, the cart should be self-contained in its logic. It
contains, as instance data, information about what's in the cart. It
has methods for manipulating that information and would expose methods
that would probably be something like:
addItem(item,quantity);
deleteItem(item);
changeQuantity(item,newQuantity);
getAllItems();
getSubTotal(); [add all prices of the items]
getAllItems might return a struct of structs, or it might return an
array of other CFC instances (instances of Item, perhaps?) -- that will
depend on your implementation, but the point I'm trying to make is that
the cart itself should not be "aware" of a session (in fact, your problem
of needing a CFAPPLICATION tag is a classic example of why a component
should minimize dependencies on the external environment). Thus, you
shouldn't ever need to pass the Session scope "into" the CFC (or out of
the CFC).
You
can just say things like:
session.cart.addItem(item,quantity);
myCartItems = session.cart.getAllItems();
or,
maybe something like:
for(item in session.cart.getAllItemKeys()){
thisItem =
session.cart.getItem(item);
}
etc.
That makes good sense ... so basically
build the "cart" in the CFC and return to the the CFM template to update
the cartData session. Keep session information out of the CFC
completly?
I would assume you would also set the session to a local
variable before it went into the CFC.
How do you handle multiple structs and arrays being passed to a
component ..
Ie, I have cartData (individual items in the cart) and then
orderData that is all the information about the cart. They
interact together (maybe I need to think more object oriented).
Paul Giesenhagen
QuillDesign
----- Original Message -----
Sent: Friday, October 03, 2003
11:21 AM
Subject: RE: [CFCDev] Just
starting CFC's -- Session Question
I
have to throw in the obligatory and oft repeated advice that you
should not be directly manipulating session variables inside your
CFCs, generally speaking. You'd be better off having your
cartModule component store things as instance variables, then store an
instance of the cartModule in the session. This way you preserve
encapsulation because the cartModule does not need to be aware of its
environment (you could, for instance, use it in the Application or
Server scope if that were more appropriate in another setting).
You also avoid any risk of overwriting the data inside the cart.
You also don't need to be aware of how the cartModule is implemented
to use it -- you can then use CFCs' strength, which is to encapsulate
complexity and expose functionality through an API defined by the
methods. Then if you ever need to change how a cartModule works
internally your other code doesn't need to change because the API of
the cartModule can stay the same.
I am just now starting my learning on
CFC's and having issues with sessions .. it is quite
frustrating.
I created a VERY simple little input
for building an array populated with a struct and then sticking it
into a session.
I am not getting any session
information from the calling CFM page .. if I set the session inside
of the CFC.
Can anyone see what I am doing
wrong?
If I run cart.cfm?mode=addCart (I
see the session set in the CFC -- cfdump)
AND then Run cart.cfm?mode=viewCart it
says cartData is undefined in SESSION.
<!--- Calling CFM page
--->
<cfparam name="url.mode"
default="">
<cfswitch
_expression_="#url.mode#">
<cfcase
value="delCart">
<cfset variables.foo =
StructDelete(session,
"cartData")>
</cfcase>
<cfcase
value="addCart">
<cfparam name="url.qty"
default="1">
<cfparam name="url.id"
default="1">
<!--- <cfobject
type="component" name="addCart"
component="test.components.cartModule">
--->
<cfinvoke
component="test.components.cartModule"
method="addCart"/>
</cfcase>
<cfcase
value="viewCart">
<cfdump
var="#session.cartData#">
</cfcase>
</cfswitch>
<!--- cartModule.cfc
--->
<cfcomponent
displayname="cartModule" hint="manages Items to the
Cart">
<cffunction name="addCart" output="true"
displayname="Adds Cart Stuff" hint="Adds Cart
Stuff">
<cfif
IsDefined("session.cartData")>
<cfset
cartLen = ArrayLen(cart) + 1>
<cfset
cart[cartLen] = structNew()>
<cfset
cart[cartLen].qty = url.qty>
<cfset
cart[cartLen].id =
url.id>
<cfelse>
<cfset
cart = arrayNew(1)>
<cfset cartLen =
ArrayLen(cart) + 1>
<cfset cart[cartLen]
= structNew()>
<cfset cart[cartLen].qty =
url.qty>
<cfset cart[cartLen].id =
url.id>
</cfif>
<cfset
session.cartData = cart>
<cfdump
var="#session.cartData#">
</cffunction>
</cfcomponent>
Also: If I call this component via
CFOBJECT the <CFDUMP in the function doesn't display anything --
If I use <CFINVOKE it displays the dump.
Thanks
Paul Giesenhagen
QuillDesign
