Скачать или смотреть How to Use Powershell ConvertFrom-Json to Select Values from Nested Arrays

Learn how to extract specific nested values from JSON using Powershell's ConvertFrom-Json, focusing on selecting item tags based on their property names.
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Extracting Nested JSON Values in Powershell: A Guide to Using ConvertFrom-Json

When working with JSON files in Powershell, a common challenge arises: how to accurately extract specific nested values, especially when dealing with arrays. If you've ever found yourself in a situation similar to the one below, you're not alone. Let's explore how to solve it effectively!

The Problem

Imagine you have a JSON file containing multiple items, each with associated tags. For example:

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

Your goal? Extract the Value of an ItemTag based on its Name, such as “Tag 4”. However, due to the unordered nature of the ItemTags, you need a reliable way to do this—relying on index numbers will not suffice.

The Solution

To address this, we can utilize Powershell's Where-Object cmdlet combined with the ConvertFrom-Json functionality. This allows us to filter through the ItemTags based on the Name property. Here's how to implement it step-by-step:

Step 1: Load the JSON Data

First, read your JSON file and convert it to a usable object. You can accomplish this using the Get-Content cmdlet combined with ConvertFrom-Json:

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

This command parses the JSON and prepares it for further manipulation.

Step 2: Extract Values Based on ItemTag Name

Next, instead of trying to access ItemTags through a fixed index, we can use a dynamic approach. The necessary expression to extract the value based on the Name property is as follows:

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

Breakdown of the Expression

$_: Represents the current object in the pipeline.

ItemTags: Accesses the nested tags.

Where-Object Name -eq 'Tag 4': Filters the ItemTags where the Name is equal to 'Tag 4'.

.Value: Retrieves the Value property from the filtered tags.

Step 3: Consider Multiple Matches

One helpful detail to keep in mind is that this will return an array. If multiple ItemTags share the same Name, the result will include all corresponding Values. For instance, in our example data, if two ItemTags had the name Tag 4, their respective values ("Yes" and "No") will be fetched simultaneously.

Conclusion

With this approach, you can dynamically select nested JSON values based on specific properties, enabling you to handle unordered data effectively. No longer are you confined to relying on hardcoded index numbers. Instead, you can confidently extract relevant information from your JSON files in a way that adapts to changing structures.

Whether you're exporting to CSV or processing data further, mastering these Powershell techniques will surely streamline your workflow when dealing with JSON data. Happy scripting!