Скачать или смотреть Unraveling JSON with jq: How to Unnest Nested Arrays into Separate Objects

Learn how to use `jq` to transform JSON data by unnesting nested arrays into multiple objects with clear examples and step-by-step instructions.
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Unraveling JSON with jq: How to Unnest Nested Arrays into Separate Objects

When working with JSON data, particularly in formats that come from APIs or databases, you might encounter scenarios where you need to transform a nested structure into a more manageable format. A common task is to unnest or unwind an array, resulting in multiple objects that each represent a single item from the original array, while maintaining other properties.

In this guide, we'll explore how to achieve this using the powerful command-line tool jq.

Understanding the Problem

Imagine you have the following JSON structure:

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

This JSON mimics a real-world data scenario where you have a root object containing an array, along with other properties. The task is to convert this nested array into separate objects while keeping other property values intact.

Desired Output

Our goal is to transform the above JSON into the following format:

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

The Solution with jq

Step-by-Step Breakdown

To achieve this transformation, we can utilize a jq command that maps through the array and restructures the objects. Here’s the command you can use:

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

Let’s dissect what this command does:

Mapping Through the Array:

The map function applies the transformation to each element of the input array.

Constructing New Objects:

The syntax {"root-property-a": ."root-array-a"[]} creates a new object for each element in the "root-array-a." The [] operator here indicates that it should fan out each value of the array into the resulting objects, creating a separate instance for each number.

Maintaining Other Properties:

The + . operator merges the newly created object with the current object, effectively retaining "root-property-b" and "root-property-c."

Removing the Unwanted Array:

Finally, the del(."root-array-a") part removes the original nested array from each object so that it no longer appears in the final output.

Running the Command

To run this command, ensure you have jq installed on your machine. You can execute it by providing the JSON input file like so:

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

Replace <input_file>.json with your actual file name which contains the JSON data.

Conclusion

Using jq to unnest arrays allows data analysts and developers to streamline their JSON data workflow, making it easier to manipulate and consume. By following the steps outlined in this post, you can keep your JSON structures clean and useful for further processing or analysis.

Whether you’re working with data from databases, APIs, or data lakes, mastering jq can significantly enhance your data manipulation capabilities.

If you found this post helpful or have questions about working with jq, feel free to leave a comment below!