Deleting associated objects from an array ColdFusion - coldfusion

Question

I have a shopping cart array which holds the product information of items in the cart. Some products which are added will be at a special discount if purchased with the "main item".
If someone adds an item which has special offers associated to it, I set a key in the item structure called mainitem with a value of yes, all the subsequent special offer items associated to the main item have key mainitem set as no and have another key named mainitemid (this is the mainitem uid).
If some one deletes the mainitem I need to ensure any related special offer items are deleted as well. This is what I am having trouble with, can't quite work out how to find them all.
I am using form.itemID to supply the item id of the product being deleted. I need to make sure the item being deleted is a main item; if so, loop through the rest of the cart and find any item with mainitemid equal to form.itemid and remove them, then delete the mainitem.
mainitem is defined as session.mycart[i].mainitem
maintitenid is defined as session.mycart[i].mainitemid
<cfloop index="i" from="1" to="#arrayLen(session.mycart)#">
</cfloop>
Do I need to create two loops or could I do it with one? I'm not sure of my conditional statements.

Answer 1

Solution for OPs specific issue
Revised to offer a more complete solution
<!--- First of all, will need to go 1 to ArrayLen() to find the main item id. Doesn't matter what order you go here, but main items should be inserted before children so may as well start at the bottom --->
<cfloop index="i" from="1" to="#ArrayLen(session.mycart)#">
<!--- Is this the main item? --->
<cfif session.mycart[i].id EQ form.itemID>
<!--- It's found the item, is it a main item? We've found the item so entering here to break the loop --->
<cfif session.mycart[i].mainitem>
<!--- Go from ArrayLen() to 1, as if you go 1 to ArrayLen() when deleting you confuse Coldfusion --->
<cfloop index="j" from="#ArrayLen(session.mycart)#" to="1" step="-1">
<cfif session.mycart[j].id EQ form.itemID OR session.mycart[j].mainitemid EQ form.itemID>
<cfset ArrayDeleteAt(session.mycart,j)>
</cfif>
</cfloop>
</cfif>
<!--- This loop is done, so break out --->
<cfbreak>
</cfif>
</cfloop>
In your post, you state you are looping from index 1 to index ArrayLen(...). If you are deleting items from the array though, Coldfusion is a bit straightforward and doesn't really pay attention and so when you delete element 2 of a 5-element array, the array becomes 4 elements long (because you deleted one) and the element which was index 3 is now index 2, thus it is missed.
The way around this is to start at the end and work backwards. As long as you are deleting at most 1 record at a time, then this is perfectly valid as it will continue reducing the index it is currently checking until you get down to 1, which will be the first element.
This way you can go through element 5, 4, 3, 2, delete element 2, and it will then check index 1 which now will still be the same item as it was when you started the loop and thus no skipping is experienced.
Some blurb on how to deal with this
I misread the question, or it got edited while writing this, but the below is applicable so leaving it here still
Have you considered having special offer items as children to the main item, as then it encapsulates the entire offer together and deleting the parent deletes the child. I've a similar issue where items have options associated with them, and to allow hierarchy to be observed I decided on creating a tree combined with a reference array. Just as a rough example to show the principle, take a look at this
<cfscript>
// Create a main item structure
stcMainItem = {
id = CreateUUID(),
somekey = somevalue,
someotherkey = someothervalue,
cost = 123
};
// Create some child item structures, special offers for ex
stcSpecialOfferItem1 = {
id = CreateUUID(),
parent = stcMainItem.id,
cost = 45
};
stcSpecialOfferItem2 = {
id = CreateUUID(),
parent = stcMainItem.id,
cost = 45
};
// Each is added to a reference array
arrItemReference = [];
arrItemRefernce.add(stcMainItem);
arrItemRefernce.add(stcSpecialOfferItem1);
arrItemRefernce.add(stcSpecialOfferItem2);
// Now you decide to delete the main item and direct parents
strIDToDelete = stcMainItem.id;
for (i=ArrayLen(arrItemReference);i>=1;i--) {
if (
arrItemReference[i].id == strIDToDelete
||
arrItemReference[i].parent == strIDToDelete
) {
ArrayDeleteAt(arrItemReference,i);
}
}
</cfscript>
In my actual code I've done this by way of creating an Item.cfc with methods to deal with the above and to cascade up the tree deleting grandchildren etc, but the principle is sound. Essentially you have methods that allow the items to be exposed as both a flat array and as a hierarchy of parents, children, and siblings.
Informational point
As an aside, you keep interchanging "array" and "structure" when the two are slightly different unlike languages like PHP where array is used to refere to both terms. An array contains values with a numeric index from 1 up to n, while a structure is an object that holds values related to arbitary keys. The reason that there is a difference though is that they don't build off the same base java objects so some methods that work on one don't work on the other.

Answer 2

<cfloop index="i" from="1" to="#arrayLen(session.mycart)#">
<cfif session.mycart[i].mainitem eq "no" AND session.mycart[i].mainitemid EQ form.itemid>
<cfset arrayDeleteAt(session.myCart,i) />
<cfset i = i - 1 /><!--- this is necessary to keep you from running out of the end of the loop --->
</cfif>
</cfloop>
This isnt tested of course and you may have to work with it to put your exact variable names in, but I think it should get you there. Let me know if I have misunderstood the question.

Answer 3

I don't see a way to do this in one loop, as I view it as a two step process. First you have to see if the item id you deleted is a main item, then go back through the array and delete the rest of the associated items.
Add StructKeyExists() as necessary.
<!--- Find Main Item --->
<cfset isMainItem = false />
<cfloop from='1' to='#ArrayLen( Session.MyCart )#' index='item'>
<cfif Session.MyCart[ item ].ItemID EQ Form.ItemID AND Session.MyCart[ item ].MainItem EQ 'Yes'>
<cfset isMainItem = true />
<cfbreak />
</cfif>
</cfloop>
<cfif isMainItem>
<!--- Clean up special offer items --->
<cfloop from='1' to='#ArrayLen( Session.MyCart )#' index='item'>
<cfif Session.MyCart[ item ].MainItemID EQ Form.ItemID AND Session.MyCart[ item ].MainItem EQ 'No'>
<cfset ArrayDeleteAt( Sesion.MyCart, Item ) />
<cfset item-- />
</cfif>
</cfloop>
</cfif>