How to Access a Nested JSON Field in PowerShell

Learn how to effectively access a nested JSON field in PowerShell, specifically focusing on Azure Advisor objects. This guide breaks down the process into clear steps.
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How to Access a Nested JSON Field in PowerShell: A Comprehensive Guide

PowerShell is a powerful tool for managing and automating tasks, particularly when working with Azure resources. However, when dealing with complex JSON objects, accessing deeply nested fields can become challenging. In this post, we'll explore how to access a specific field in a JSON object created by Azure Advisor using PowerShell, breaking down the steps for clarity.

Understanding the Problem

Imagine you are retrieving data from Azure Advisor, and you encounter a JSON object that contains various properties, including nested ones. Here's an example of such an object:

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

In this JSON structure, you want to access the savingsCurrency field, which is located within the additionalInfo object. The complexity arises because you're trying to access it after converting the additionalInfo to JSON format.

The Solution

Key Insight

The critical issue lies in how you're handling the nested properties. When you convert the additionalInfo object to JSON using the ConvertTo-Json command, you effectively change it from an object to a string. This conversion prevents you from accessing its properties directly.

Correcting the Code

Here's how you can modify your PowerShell script to access the savingsCurrency property correctly:

Maintain the Object Type: Instead of converting additionalInfo to a JSON string right away, keep it as an object during the checks.

Check for Null: Make sure to check if additionalInfo is not null or empty before accessing its properties.

Convert When Necessary: Only convert to JSON when you need to display or log the information.

Here’s the revised script:

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

Explanation of Changes

Removed the Double Conversion: We no longer convert additionalInfo to JSON before checking its properties, allowing us to access savingsCurrency directly as a property of an object.

Outputting as JSON: We only convert to JSON when we want to display the structure, which ensures we maintain the integrity of the object type during conditional checks.

Expected Output

With these changes in place, you should now see the expected output, including the correct value of savingsCurrency:

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

Conclusion

Accessing nested fields in a JSON object in PowerShell can be tricky, especially when dealing with data from Azure. By keeping the data as an object until you need to output it as JSON, you can simplify your process of accessing specific fields.

Feel free to adapt the approach detailed above to your own scripts, and always ensure you are managing data types appropriately when working with PowerShell.