Class wwBusinessChildCollection - West Wind Client Tools

Class wwBusinessChildCollection

This class, subclasses from the wwBusinessObject class, is used to represent a list of objects as are commonly used in child objects in one to many relations. A typical example might be the lineitems of an invoice. This class uses an internal public oRows Collection member to contain the actual data items of the child data which can be loaded with the LoadFromCursor() method which loads the array members from a cursor. Since this object is subclasses from wwBusinessObject you can use it to manage both the list as well as individual items in that list.

You can use this mechanism as the offline storage for things like lineitems on an invoice for example. To actually manipulate each item you can do something like this to use the 'full' business object to use the data:

*** cLineItems here is subclassed from wwBusinessChildCollectionList
*** and is bound to a line items table
oInvoice.oLineItems = oInvoice.CreateChildObject("cLineItems")
oInvoice.oLineItems.LoadFromCursor()

*** Retrieve the first item of the collection and store it to the local oData member
oInvoice.oLineItems.oData  = oInvoice.oLineItems.Item(1)

*** Write it out
oInvoice.oLineItems.Save()

This would be using the default .Save() method which saves an individual lineitem.

Alternately you can use the LoadFromCursor() and SaveToCursor() methods to simply load and save the list as a whole:

oInvoice.oLineItems = oInvoice.CreateChildObject("cLineItems")
oInvoice.oLineItems.LoadFromCursor()

*** Retrieve the first item of the Collection and store it to the local oData member
oInvoice.oLineItems.oRows[1].Description = "New Description 1"
oInvoice.oLineItems.oRows[2].Description = "New Description 2"

*** Now go write back all the lineitems
oInvoice.oLineItems.SaveToCursor()

The code for both of these type of operations probably should be wrapped into the cLineitems class internally for better design and then have methods such as LoadLineItems() and SaveLineItems() which encapsulate this behavior.

Parent Class: wwBusinessObject

Custom
wwBusinessObject
wwBusinessChildCollection

Class Members

Member		Description
	Add	Adds an item to the array manually. This should be an object either from a SCATTER NAME or from CREATEOBJECT("SomewwBusiness subclass"). o.Add(loItem)
	Clear	Clears the entire oRows collection. o.Clear()
	Item	Retrieves an item from the collection by index count. Note you can also use `loBus.oRows[x]` to retrieve items. o.Item(lnIndex)
	LoadFromCursor	Loads the `oRows` collection with the contents of the active cursor. The active cursor should reflect the business object you are loading into. o.LoadFromCursor(lcBusObjectClass, lcCursor)
	Remove	Removes an item from the oRows collection. o.Remove(lnIndex)
	SaveToCursor	Saves each of the items in the collection to disk using individual item `.Save()` calls. Loads the oData member for each operation then performs a `.Save()` for each if the object is a business object. o.SaveToCursor(llCollectionHoldsClass, llUseTransaction)
	nCount	Number of items in the list.
	oRows	A collection of row objects that contains one object for each element. Each object is created with SCATTER NAME from the LoadFromCursor() method.

Requirements

Assembly: wwBusinessObject.prg