# Tree Transform

The *Tree Transform* object in Astera Data Stack enables users to transform data in a hierarchical structure. Users can create new fields in the parent node based on the data in the collection/child node. *Tree Transform* supports rule-based routing, filtering, merging, and sorting of data while maintaining its hierarchy.

{% embed url="<https://youtu.be/_yrhfQBWPUY?list=PLmyM3TZtVUyJfz1bkpZ-CxJ33fAwHIbug>" %}

### Use Case

In this case, we are using the [*XML/JSON File Source*](/astera-data-stack-v9/dataflows/sources/xml-json-file-source.md) to extract our source data.&#x20;

![](/files/t1J0WQthn3dlS8CcBaaP)

The source file contains customers’ information in the parent node and their orders and shipping details in the collection/child node.

You can preview this data by right-clicking on the source object’s *Header > Preview Output.*

![](/files/fBI2Nu8x0zEq1g9niGVx)

A *Data Preview* window will open, displaying a preview of the hierarchical source data.

![](/files/BQHzrTFvqt0gFbbnwlXS)

Now, we want to create a new field in the parent node that contains the count of orders that arrived late for each customer and route these records to a destination file, all while maintaining the hierarchical format of the dataset.

This new field in the parent node will depend on two fields: *RequiredDate* and *ShippedDate*, that are already present in the collection/child node.

In other words, we are trying to transform hierarchical data without flattening its structure.

### Using Tree Transform Transformation

1. To get a *Tree Transform* object from the *Toolbox*, go to *Toolbox > Transformations > Tree Transform* and drag and drop the *Tree Transform* object onto the designer.

![](/files/pnUmNXadEoI55AFwlMxw)

The transformation object is empty right now. This is because we have not mapped any fields to it yet.

2. Auto-map source fields onto the transformation by dragging and dropping the root node of the source object *CustomerOrders* onto the root node of the transformation object – *TreeXform*.

![](/files/QAz6ZiTEVwaoUYg9totN)

Now that the mapping is done, let’s configure the *TreeXfrom* object.

### Configuring the Tree Transform Object

1. Right-click on the object’s header and select *Properties* from the context menu. A configuration window for *Tree Transform* will open. The first window is the *Layout Builder* window. This is where we can create or delete fields, change their name or data types, mark any field as a variable, or attach expressions to fields.

![](/files/L9yUQzwuyVfxKKuuv1BD)

2. Create a new field under the parent node. Let’s name it *LateOrders*.

![](/files/sHwZLY92q4NR0bLhJGfI)

3. Click *Next*, and you will be directed to a *Layout Modifications* window.

![](/files/CfbVnWY3rd5KbUyZUCS3)

4. Select the *LateOrders* field. Here you can modify any field by applying expressions to it.

![](/files/aLVPaGaSGJNcyZnoWuzg)

5. Write the expression that counts the number of late-arriving orders.

Click *“…”* next to the expression box to open the *Expression Builder* where you can make use of the extensive library of built-in functions and expressions in Astera.

![](/files/p0No6Wad1t17yPaT0yOD)

This creates the field values for *LateOrders* based on the field values of the *RequiredDate* and *ShippedDate* fields.

6. Click on the *Orders* node and a panel *(Options for Collection)* will appear. These options are only available for collection nodes.

![](/files/pFqpVROY9xfeRPRVSvYi)

*Options for Collection*:

* *Show* – Shows collection node in the *Tree Transform* object.
* *Flatten With Item Count* – Flattens data based on the record count in the collection node against each item in the parent node.
* *Flatten Based on Rules* – Flattens a part of hierarchical data based on predefined rules.
* *Route Based on Rules* – Routes and creates subsets of data based on predefined rules.
* *Merge With Item Count* – Merges data based on the record count in the collection node against each item in the parent node.
* *Hide* – Hides collection node from the *Tree Transform* object.
* *Calculation Formula* – An expression box used for writing rules to route or flatten hierarchical data.
* *Sort Based On Keys* – Sorts hierarchical data based on the field in the collection node. Only available for *Show* and *Flatten With Item Count* options.

This is where we will specify the rule for routing late-arriving orders. Select *Route Based on Rules*. A new section for adding rules will appear in the window.

![](/files/EzXeZbGtx4ZGB2qiHtY8)

7. Add a new rule by clicking on the *Add switch condition* icon ![9\_icon](/files/iZrKlysyZUdlcwPLSBSM). Now, write an expression to route late arriving orders and name this rule “LateArrivals”.

![](/files/R7cWHxgjgNIUvQwZO266)

8. Click *OK*. Now observe that a new collection node *Orders\_LateArrivals* has been added to the *Tree Transform* object.

![](/files/L28vDaBxS2gcw7c4zrEy)

To preview data, right-click on the header of the transformation object and select *Preview Output* from the context menu.

![](/files/EZ49cYzFCMp3ppxFH4sU)

A *Data Preview* window will open. On expanding the records, you will get corresponding order details and appended details of late-arriving orders.

![](/files/d70FDN4uxPZ72MAlBYiR)

To store the output for late arriving orders, you can write it to a destination file or use that data further in the dataflow.

This concludes using the *Tree Transform* transformation object in Astera Data Stack.


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