How to Dynamically Update JSON Values in PowerShell with Set-ByPath Functionality

Learn how to effectively update JSON values in PowerShell using a dynamic approach with the `Set-ByPath` function. This guide will help you understand the process step-by-step.
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This video is based on the question https://stackoverflow.com/q/70156784/ asked by the user 'AdamCodes716' ( https://stackoverflow.com/u/13382745/ ) and on the answer https://stackoverflow.com/a/70156951/ provided by the user 'Mathias R. Jessen' ( https://stackoverflow.com/u/712649/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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How to Dynamically Update JSON Values in PowerShell with Set-ByPath Functionality

PowerShell is a powerful scripting language that provides users with easy ways to manage JSON files. However, one common challenge developers face is updating specific values in a JSON object dynamically. This guide will guide you through solving the problem of setting a value in a nested JSON structure when only a path string to that value is known.

The Problem

Imagine you have a JSON file that looks something like this:

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You have the path to the value you want to change stored as a string in a variable called $name. For example:

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You want to update the loginName under primaryContact to a new value, but you're unsure how to dynamically reference that nested structure.

Attempting to execute the following command:

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will lead to an error:

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Understanding the Issue

The error arises because PowerShell tries to resolve $name as a single property, leading it to search for a property named primaryContact.loginName. Instead, you need to navigate down through each level of the object individually to set the desired value.

The Solution: Using the Set-ByPath Function

To successfully update a nested JSON property with a dynamic path, you'll need to create a custom function—let's call it Set-ByPath. This function will take three parameters:

$RootObject: The root JSON object you're working with.

$Path: The path string to the specific value you want to change.

$NewValue: The new value you want to set.

Step-by-Step Breakdown

Here’s how to implement the Set-ByPath function:

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Using the Function

With the Set-ByPath function defined, you can easily update your JSON data. Here’s how you can use it:

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This code performs the following:

Defines a Path: The string variable $name contains the path to the value you want to update.

Loads JSON Data: Converts a JSON string into a PowerShell object.

Calls the Function: Uses the Set-ByPath function to update the loginName field.

Conclusion

With the Set-ByPath function, you can dynamically update values in nested JSON structures by referencing paths in a simple string format. This not only simplifies your scripting tasks but also enhances the overall flexibility of your scripts.

Next time you need to update a JSON file in PowerShell, use this method, and make your coding life much easier!