How to Unnest Arrays and Add Array Names in JSON Using JOLT

Learn how to unnest arrays and add array names as additional fields in JSON with JOLT. Simplify your JSON transformations using this step-by-step guide.
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Introduction

When working with JSON data, you may encounter scenarios where you need to unnest arrays and incorporate array names as additional fields for better organization and clarity. This problem is particularly common in data management and analysis, where nested structures can complicate processing and extraction. Today, we'll explore a robust solution using JOLT, a simple JSON transformation library.

The Problem

Consider the JSON structure represented below:

[[See Video to Reveal this Text or Code Snippet]]

From this structure, our goal is to unnest both arrays (dimensions and metrics) while adding a new field metadata_object that specifies the origin of each object (either dimensions or metrics). The expected output will look like this:

[[See Video to Reveal this Text or Code Snippet]]

The JOLT Solution

To achieve this transformation, we can leverage JOLT with a concise specification that can handle both arrays simultaneously. Here’s how you can do it:

JOLT Transformation Spec

The following JOLT spec will effectively transform your JSON data as desired:

[[See Video to Reveal this Text or Code Snippet]]

Breakdown of the JOLT Spec

First Shift Operation:

This operation extracts each element from both dimensions and metrics arrays.

It passes down the original key names while creating a new field metadata_object with the appropriate array name.

Second Shift Operation:

This simply allows for further flattening of the structure, ensuring that our final output is correctly formatted as a flat array.

Conclusion

By following the steps outlined above, you can easily unnest both dimensions and metrics arrays from your JSON data while adding the relevant metadata_object fields. The JOLT library provides a versatile and powerful way to transform and manipulate JSON structures, making complex data operations much more manageable.

Now, you have a powerful tool in your arsenal to streamline your JSON data management tasks effectively!