How to Add a Field to JSON in the Middle of a Structure Using JOLT

Discover how to effectively modify your JSON structure by adding fields in specific positions using JOLT transformations. Find a step-by-step guide to achieve the desired format!
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How to Add a Field to JSON in the Middle of a Structure Using JOLT

JSON (JavaScript Object Notation) is a popular data format often used for communication between web servers and clients. Sometimes, you may need to modify an existing JSON structure by adding new fields at specific locations. This guide addresses a common problem: how to insert a new field in a JSON structure at a desired position using JOLT transformations.

The Problem

You have a JSON structure and need to insert a new field, timestamp_dt, in a specific order relative to other fields. Unfortunately, if you only use the default operation in JOLT, the new field gets automatically appended to the end of the JSON object, rather than being placed before an array, as you might intend. Here’s the original JSON structure you’re working with:

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

Desired Output

The expected output is:

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

As illustrated, the timestamp_dt field is now in the desired position within the JSON structure.

The Solution

To achieve the desired outcome, you can use the JOLT shift transformation, allowing you to specify the order of each field individually. Here’s how to implement this step by step.

Step 1: Use the default Operation

First, specify the default value for the new field. This is done using the default operation where you set the key and value you want to add.

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

Step 2: Use the shift Operation

Next, apply the shift operation to rearrange the fields in the desired order. This will ensure that timestamp_dt appears precisely where you want it relative to the existing fields.

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

Explanation of Shift Spec

The shift operation uses the & character to denote that the value of the field should be retained.

By explicitly ordering the fields, you can control where the new timestamp_dt field is placed, while preserving the structure of collectedData as you intended.

Conclusion

Using the JOLT default and shift operations together allows you to modify JSON structures effectively, inserting new fields at desired positions rather than appending them at the end. By following the steps outlined in this guide, you can create JSON outputs that meet your specific formatting requirements with ease.

Next time you need to add fields to your JSON in a precise order, remember this simple approach! Happy coding!