====== Build a hierarchy using function SplitToArray() ======

To derive a hierarchy from a given structure there is ideally a **parent-child** relationship of the individual tuples.
In such a case, the function [[en:transformation:mappings:funktionen:gruppierung:buildhierarchy|]] can be used to create the hierarchy.

__If a direct **parent-child** relationship is only possible via the sequence of tuples and unique **parent** or **child** characteristics((Similar to the handling of record types in FlatFiles.)), the following approach can be chosen:__

===== Solution approach =====

We use the following functions and components:
  - [[en:transformation:mappings:variablen:doubledollar|]]
  - [[en:transformation:mappings:funktionen:string:splittoarray|]]
  - Selektionsmodus: concatenate
  - XPATH Filter

==== Procedure in Mapping ====

First we store the tupples all in a [[en:transformation:mappings:variablen:doubledollar|]] with name $$Position to run through them in the next step.
We then filter out the tuples by **parent** or **child** characteristic to form a string containing the hierarchy((In this case we distinguish by the first 3 digits of the item number.)).
By cleverly applying the selection mode "concatenate" on the rule sets and controlling the separators((Here "**,**" as separator for mainPositions and "#" for SubPositions.)) a string can be formed according to the following pattern:
<code>MainPositionID1,MainPositionID2#SubPositionID1#SubPositionID2,MainPositionID3#SubPositionID1</code>
This hierarchy string can finally be split with [[en:transformation:mappings:funktionen:string:splittoarray|]] and the separator "**,**" into the main positions, which trigger **Positions** in the target object
and then for sub-items are again individually resolved after the separator "#" into the sub-items, which are triggered in the shown example below **Positions** as **CustomItems** in the MiddleWare((Or in the respective target object.)).

{{:howtos:splittoarray_build_hierarchy.jpg?nolink|}}

{{:images:sign_warning.png?nolink|}}**Note:** If the same item numbers are expected to come in different positions, then the original position number must be taken into account when creating the hierarchy!
==== Advantage ====

We avoid an intermediate mapping((This would be a classic solution with extra mapping.)) which could contain the parent-child relationship.