Enumerate Rest API Result Returned as Nested PSCustomObjects: A Step-by-Step Guide

Are you tired of struggling to make sense of the complex data structures returned by your REST API? Do you find yourself lost in a sea of nested objects, unsure of how to extract the information you need? Fear not, dear reader, for today we shall embark on a journey to tame the beast that is the REST API result returned as nested PSCustomObjects!

What are PSCustomObjects?

Before we dive into the meat of the article, let’s take a quick detour to discuss what PSCustomObjects are. In PowerShell, a PSCustomObject is a custom object that allows you to create your own objects with properties and values. Think of it like a container that holds a collection of key-value pairs. When working with REST APIs, the result is often returned as a JSON object, which PowerShell conveniently converts into a PSCustomObject.

The Challenge: Enumerating Nested PSCustomObjects

The problem arises when the REST API result is returned as a nested structure of PSCustomObjects. Imagine receiving a response like this:

{
    "data": {
        "user": {
            "id": 1,
            "name": "John Doe",
            "address": {
                "street": "123 Main St",
                "city": "Anytown",
                "state": "CA",
                "zip": "12345"
            }
        }
    }
}

Your task is to extract the individual properties and values from this nested structure. Sounds daunting, doesn’t it? But fear not, for we shall break it down step by step.

Step 1: Converting the JSON Response to a PSCustomObject

The first step is to convert the JSON response into a PSCustomObject. You can do this using the `ConvertFrom-Json` cmdlet:

$response = Invoke-WebRequest -Uri "https://api.example.com/users"
$pso = $response | ConvertFrom-Json

In this example, we’re using the `Invoke-WebRequest` cmdlet to send a GET request to the API, and then piping the response to the `ConvertFrom-Json` cmdlet to convert it into a PSCustomObject.

Step 2: Enumerating the Top-Level Properties

Now that we have our PSCustomObject, let’s start enumerating the top-level properties:

$pso | Get-Member -MemberType Property

   TypeName: System.Management.Automation.PSCustomObject

Name        MemberType   Definition
----        ----------   ----------
data        NoteProperty string data=...

In this example, we’re using the `Get-Member` cmdlet to retrieve the properties of the PSCustomObject. We’re filtering the results to only show properties using the `-MemberType` parameter.

Step 3: Enumerating the Nested Properties

Now that we have the top-level properties, let’s dive deeper and enumerate the nested properties:

$pso.data | Get-Member -MemberType Property

   TypeName: System.Management.Automation.PSCustomObject

Name          MemberType   Definition
----          ----------   ----------
user          NoteProperty string user=...

In this example, we’re accessing the `data` property and using `Get-Member` to retrieve its properties.

Step 4: Enumerating the Nested Nested Properties (Yes, You Read That Right!)!

We’re not done yet! Let’s enumerate the properties of the `user` object:

$pso.data.user | Get-Member -MemberType Property

   TypeName: System.Management.Automation.PSCustomObject

Name      MemberType   Definition
----      ----------   ----------
address  NoteProperty string address=...
id       NoteProperty int id=1
name     NoteProperty string name=John Doe

In this example, we’re accessing the `user` property and using `Get-Member` to retrieve its properties.

Step 5: Extracting the Individual Properties and Values

Finally, we can extract the individual properties and values using dot notation:

$pso.data.user.id
$pso.data.user.name
$pso.data.user.address.street
$pso.data.user.address.city
$pso.data.user.address.state
$pso.data.user.address.zip

In this example, we’re using dot notation to access the individual properties and values.

Using a Recursive Function to Enumerate the PSCustomObject

What if you need to enumerate a deeply nested PSCustomObject? Writing a recursive function can be a elegant solution:

function Enumerate-PSCustomObject {
    param ($pso)

    foreach ($property in $pso.PSObject.Properties) {
        if ($property.Value -is [PSCustomObject]) {
            Enumerate-PSCustomObject -pso $property.Value
        } else {
            Write-Host "$($property.Name) = $($property.Value)"
        }
    }
}

Enumerate-PSCustomObject -pso $pso

In this example, we’re defining a recursive function `Enumerate-PSCustomObject` that takes a PSCustomObject as input. The function iterates through the properties of the PSCustomObject, and if the value is another PSCustomObject, it calls itself recursively. If the value is not a PSCustomObject, it prints the property name and value to the console.

Conclusion

Cmdlet	Description
ConvertFrom-Json	Converts a JSON string into a PSCustomObject
Get-Member	Retrieves the properties and methods of an object
Invoke-WebRequest	Sends a web request to a specified URI

By following these steps and using the techniques outlined in this article, you’ll be well on your way to mastering the art of enumerating REST API results returned as nested PSCustomObjects. Happy coding!

• Enumerate the top-level properties of the PSCustomObject using `Get-Member`
• Enumerate the nested properties using dot notation
• Use a recursive function to enumerate deeply nested PSCustomObjects
• Extract individual properties and values using dot notation

Further Reading

If you’re interested in learning more about working with REST APIs in PowerShell, I recommend checking out the following resources:

1. Invoke-WebRequest
2. ConvertFrom-Json
3. Get-Member

I hope this article has been informative and helpful. Happy coding, and remember to stay curious!

Frequently Asked Question

Having trouble navigating the world of Rest APIs and PSCustomObjects? Worry no more! We’ve got you covered with these frequently asked questions and answers.