ColdMVC: Flatten an array of objects with children.

In record based systems "non object based" if you wanted to store a parent/child relationship you usually stored a parent_id on the same table.

Example:

CMS example showing a page table where a page can have many pages underneath it.

Page table.
ID,Name,Address,Parent_ID
1,Products,products/,null
2,Tiles,products/tiles/,1

Then in order to simulate an object based system, you usually loop the query and put the records in structs of structs.

Example.

result = {
id="1",
name="Products",
address="products/",
children=[
{
id="1",
name="Products",
address="products/",
children=[]
}
]
}

Notice there is children an array.

Using ColdMVC we actually start with "struct of structs" or object based, instead of starting with a query. So we need to take the objects array, we are using array of objects because that is what is return from an hql query, and pull out the children and put them in the array, thus flattening the tree.

To do this I run it through a helper function I made below.

<cffunction name="flattenArrayTree" access="public" output="false" returntype="array"> 
  <cfargument name="array" required="true"/> 
  <cfargument name="result" required="false" default="#[]#"/> 
  <cfargument name="treeDepth" required="false" default="0"/> 
  <cfargument name="childrenPropertyName" required="false" default="children" hint="A property with an array of child objects."/> 

  <cfset var local = {}/> 
  <cfset var i = ""/> 

  <cfloop from="1" to="#arrayLen(arguments.array)#" index="i"> 
  
   <cfset local.object = arguments.array[i]/> 
   
   <cfset local.object.setTreeDepth(arguments.treeDepth)/> 
   
   <cfset arrayAppend(arguments.result,local.object)> 
   
   < !---make sure the "children" property exists is in the object---> 
   <cfif not structKeyExists(local.object,"set"&arguments.childrenPropertyName)> 
   
    <cfthrow detail="The argument childrenPropertyName which is currently #arguments.childrenPropertyName# does not exist as a property in the object"/> 
   
   < /cfif> 

   <cfif arrayLen(local.object._get(arguments.childrenPropertyName)) gt 0> 
   
    <cfset arguments.treeDepth++/> 
    
    <cfset arguments.result = flattenArrayTree(local.object._get(arguments.childrenPropertyName),arguments.result,arguments.treeDepth)/> 
    
    <cfset arguments.treeDepth--/> 
    
   < /cfif> 

  < /cfloop> 
  
  <cfreturn arguments.result/> 

 < /cffunction> 

You will notice I add a property called "treeDepth". In order to use the function you need to add a property to the model cfc called "treeDepth". Don't worry about it being added to db, if it's not mapped in hibernate file it won't be added to the db. I use the treeDepth property to know how far in a child object is. Technically...you don't need this, but I find a very handy.