Hi,
A couple times now, I've run across circular dependency issues where I get the JRUN servlet error "500 null" on the screen when I call getBean(). In my case, it is usually because component A depends on B depends on C depends on A. These circular dependencies can be hard to track down.
I know I can get around this by using setter injection instead of constructor injection, but my existing code has around 60 service layer components handled by CS and I find constructor-injection easier to manage.
Are there any recommendations on how to avoid service layer circular dependencies in general?
I've played around with DefaultXMLBeanFactory.cfc and added an argument to getBean() and constructBean() to try to detect circular dependencies. I think it might need to be modded to work with non-singletons. I pasted the diff below.
Jon
bash-2.05b$ diff DefaultXmlBeanFactory-original.cfc DefaultXmlBeanFactory.cfc
<cfargument name="beanRetrievalData" required="false" type="struct" default="#StructNew()#" hint="struct to place information about how we retrieve the bean"/>
321a323
332c334
< <cfset constructBean(arguments.beanName)/>
---
<cfset constructBean(arguments.beanName,false,arguments.beanRetrievalData)/>
337c339
< <cfreturn constructBean(arguments.beanName,true)/>
---
<cfreturn constructBean(arguments.beanName,true,arguments.beanRetrievalData)/>
340c342
< <cfreturn variables.parent.getBean(arguments.beanName)>
---
<cfreturn variables.parent.getBean(arguments.beanName, arguments.beanRetrievalData)>
355c357
< <cfargument name="returnInstance" type="boolean" required="false" default="false"
---
<cfargument name="returnInstance" type="boolean" required="true"
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<cfargument name="beanRetrievalData" required="true" type="struct" hint="struct to place information about how we retrieve the bean"/>
380a384,392
<cfif NOT StructKeyExists(arguments.beanRetrievalData, "constructedBeans") >
<cfset arguments.beanRetrievalData.constructedBeans = ArrayNew(1)>
</cfif>
<cfif ListFindNoCase( ArrayToList(arguments.beanRetrievalData.constructedBeans), arguments.beanName ) >
<cfthrow type="coldspring.CircularDependencyException" detail="Bean: #arguments.beanName# has already had a request to be constructed. This is a circular dependency."/>
</cfif>
<cfset ArrayAppend(arguments.beanRetrievalData.constructedBeans, arguments.beanName) />
527c539
< value="#getBean(argDefs[arg].getValue())#"/> <!--- value="#dependentBeanInstance#" --->
---
value="#getBean(argDefs[arg].getValue(), arguments.beanRetrievalData)#"/> <!--- value="#dependentBeanInstance#" --->
