In AS3/Flex, how can I get from flat data to hierarchical data? - apache-flex

Question

I have some data that gets pulled out of a database and mapped to an arraycollection. This data has a field called parentid, and I would like to map the data into a new arraycollection with hierarchical information to then feed to an advanced data grid.
I think I'm basically trying to take the parent object, add a new property/field/variable of type ArrayCollection called children and then remove the child object from the original list and clone it into the children array? Any help would be greatly appreciated, and I apologize ahead of time for this code:
private function PutChildrenWithParents(accountData : ArrayCollection) : ArrayCollection{
var pos_inner:int = 0;
var pos_outer:int = 0;
while(pos_outer < accountData.length){
if (accountData[pos_outer].ParentId != null){
pos_inner = 0;
while(pos_inner < accountData.length){
if (accountData[pos_inner].Id == accountData[pos_outer].ParentId){
accountData.addItemAt(
accountData[pos_inner] + {children:new ArrayCollection(accountData[pos_outer])},
pos_inner
);
accountData.removeItemAt(pos_outer);
accountData.removeItemAt(pos_inner+1);
}
pos_inner++;
}
}
pos_outer++;
}
return accountData;
}

Answer 1

I had a similar problem with a hierarchical task set which was slightly different as it has many root elements, this is what i did, seems good to me:
public static function convertFlatTasks(tasks:Array):Array
{
var rootItems:Array = [];
var task:TaskData;
// hashify tasks on id and clear all pre existing children
var taskIdHash:Array = [];
for each (task in tasks){
taskIdHash[task.id] = task;
task.children = [];
task.originalChildren = [];
}
// loop through all tasks and push items into their parent
for each (task in tasks){
var parent:TaskData = taskIdHash[task.parentId];
// if no parent then root element, i.e push into the return Array
if (parent == null){
rootItems.push(task);
}
// if has parent push into children and originalChildren
else {
parent.children.push(task);
parent.originalChildren.push(task);
}
}
return rootItems;
}

Answer 2

Try this:
AccountData:
public class AccountData
{
public var Id:int;
public var ParentId:int;
public var children:/*AccountData*/Array;
public function AccountData(id:int, parentId:int)
{
children = [];
this.Id = id;
this.ParentId = parentId;
}
}
Code:
private function PutChildrenWithParents(accountData:ArrayCollection):AccountData
{
// dummy data for testing
//var arr:/*AccountData*/Array = [new AccountData(2, 1),
// new AccountData(1, 0), // root
// new AccountData(4, 2),
// new AccountData(3, 1)
// ];
var arr:/*AccountData*/Array = accountData.source;
var dict:Object = { };
var i:int;
// generate a lookup dictionary
for (i = 0; i < arr.length; i++)
{
dict[arr[i].Id] = arr[i];
}
// root element
dict[0] = new AccountData(0, 0);
// generate the tree
for (i = 0; i < arr.length; i++)
{
dict[arr[i].ParentId].children.push(arr[i]);
}
return dict[0];
}
dict[0] holds now your root element.
Maybe it's doesn't have the best possible performance but it does what you want.
PS: This code supposes that there are no invalid ParentId's.

Answer 3

Here's what I ended up doing, apparently you can dynamically add new properties to an object with
object['new_prop'] = whatever
From there, I used a recursive function to iterate through any children so you could have n levels of the hierarchy and if it found anything it would pass up through the chain by reference until the original function found it and acted on it.
private function PutChildrenWithParents(accountData : ArrayCollection) : ArrayCollection{
var pos_inner:int = 0;
var pos_outer:int = 0;
var result:Object = new Object();
while(pos_outer < accountData.length){
if (accountData[pos_outer].ParentId != null){
pos_inner = 0;
while(pos_inner < accountData.length){
result = CheckForParent(accountData[pos_inner],
accountData[pos_outer].ParentId);
if ( result != null ){
if(result.hasOwnProperty('children') == false){
result['children'] = new ArrayCollection();
}
result.children.addItem(accountData[pos_outer]);
accountData.removeItemAt(pos_outer);
pos_inner--;
}
pos_inner++;
}
}
pos_outer++;
}
return accountData;
}
private function CheckForParent(suspectedParent:Object, parentId:String) : Object{
var parentObj:Object;
var counter:int = 0;
if ( suspectedParent.hasOwnProperty('children') == true ){
while (counter < suspectedParent.children.length){
parentObj = CheckForParent(suspectedParent.children[counter], parentId);
if (parentObj != null){
return parentObj;
}
counter++;
}
}
if ( suspectedParent.Id == parentId ){
return suspectedParent;
}
return null;
}