Magnus,
Instead of instantiating OrderDAO within Order, consider passing Order into
OrderDAO whenever you need to. I always instantiate the DAO each time i need
it. Here's an example, assuming Order is in session scope:
from somewhere in your app:
<cfset createObject('component','OrderDAO').init(
session.Order).read(idOrder) />
from OrderDAO
<cffunction name="init" access="public" returntype="OrderDAO"
output="false">
<cfargument name="Order" type="Order" required="Yes" />
<cfset variables.Order = arguments.Order />
<cfset variables.dsn = arguments.dsn />
<cfreturn this />
</cffunction>
.....
<cffunction name="read" access="public" returntype="VOID"
output="false">
<cfargument name="idOrder" type="numeric" required="yes" />
<cfset var qRead = "" />
<cfquery name="qRead" datasource="#variables.dsn#">
SELECT *
FROM tblOrder
WHERE idOrder = <cfqueryparam cfsqltype="cf_sql_integer"
value="#arguments.idOrder#" />
</cfquery>
<cfif qRead.RecordCount GT 0>
<cfset
variables.Order.setInstanceFromStruct(queryRowToStruct(qRead)) />
</cfif>
</cffunction>
.....
<cffunction name="queryRowToStruct" access="private" returntype="struct"
hint="I return a structure from a queryRow passed into
me."
output="false">
<cfargument name="query" required="Yes" type="query" />
<cfargument name="row" type="numeric" default="1" />
<cfset var ii=1 />
<cfset var cols = listToArray(query.columnList) />
<cfset var structReturn = StructNew() />
<cfscript>
for(ii = 1; ii lte arraylen(cols); ii = ii + 1){
structReturn[cols[ii]] =
query[cols[ii]][arguments.row];
}
</cfscript>
<cfreturn structReturn />
</cffunction>
If you like, post a shortened list of your Order properties and i'll post
back a BO / DAO pair showing you how i'm doing this for you to study and
adapt. I have to go out for a few hours now, so i could only do this a
little later.
ciao,
Nando
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
Behalf Of Magnus Wege
Sent: Saturday, November 13, 2004 2:37 PM
To: [EMAIL PROTECTED]
Subject: [CFCDev] Problems with inheritance and DAO Objects
Hi everyone,
I am quite new in applying OOD/P to CF via implementing cfcs. So here is my
problem:
I have a CFC called Order.cfc.
Within this CFC I create several DAO Objects (e.g. for related customers
instantiating the CustomerDAO.cfc)
So far so good.
Now I want all the SQL stuff from the Order.cfc out of it and put it to
OrderDAO.cfc.
So I created a new property of the Order.cfc by instantiating the
OrderDAO.cfc through the init-Method of the Order.cfc:
<cfset this.oOrderDAO = createObject("component","OrderDAO").init() />
By the getter-Method in the Order.cfc I can get access to these DAO-Objects.
<cffunction name="getOrderDAO" output="false" returntype="struct">
<cfreturn this.oOrderDAO/>
</cffunction>
Now I want to set my properties (all the variables in the this-scope) via
calling the method selectOrders() and calling the mother's method in
Order.cfc named setOrdersByStruct(queryResult) in the OrderDAO.cfc using
super.setVertragByStruct()
<cffunction access="public" name="selectVertrag" output="true">
<cfargument name="iVertragID" type="numeric"
required="true"/>
<cfquery name="variables.qSelectVertrag"
datasource="#this.sDsn#">
SELECT
*
FROM
Order
WHERE
pk_Order = #val(arguments.iOrderID)#
</cfquery>
<cfset
super.setVertragByStruct(variables.qSelectVertrag, "query")/>
</cffunction>
An other issue is that I need to get the properties (through the
getter-Methods) of the mother's cfc in the child CFC. As I know I cannot get
direct access to the this-scope in the mother CFC, so the getter-Method
fails.
How can I do apply the DAO-Pattern correctly? I heard something of a
Transfer Object that may be the golden key to solve this problem. Can
anybody explain this to me please?
Great thanks in advance for any help. I am looking forward to your replies.
Magnus Wege
____________________________________________
web-shuttle AG | Tel +49 89 130 145-0
Wilhelm-Hale-Str. 53 | Fax +49 89 130 145-10
D-80639 Munich | Germany
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