How to Perform a POST Request in PowerShell 2.0 Using WebRequest

Описание: Learn how to handle `POST` requests in PowerShell 2.0 by using the System.Net.WebRequest class instead of the Invoke-RestMethod cmdlet.
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This video is based on the question https://stackoverflow.com/q/62999825/ asked by the user 'Sabbir Ahmed' ( https://stackoverflow.com/u/6648701/ ) and on the answer https://stackoverflow.com/a/63002564/ provided by the user 'ekeeling' ( https://stackoverflow.com/u/6786023/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Understanding Powershell 2.0 Web Requests

If you're just starting out with PowerShell and need to make API requests, you might find yourself struggling when using PowerShell 2.0. This version doesn't support Invoke-RestMethod, which can make posting data to an API challenging. In this guide, we'll go through how to use the System.Net.WebRequest class to perform POST requests effectively.

The Problem

Many beginners encounter difficulties when trying to utilize the functionalities of PowerShell 2.0 to perform web requests. Here's a specific example of a user trying to achieve the following:

Create a JSON body for an API request.

Execute a POST request to a specified URL.

Retrieve and handle the response effectively.

While the usage of Invoke-RestMethod simplifies these tasks, it's not available in PowerShell 2.0. To overcome this, we'll implement a custom function using .NET classes.

The Solution: Creating a Custom InvokeRest Function

Step 1: Define the Function

We'll create a function named InvokeRest, which takes parameters for the URL, content type, request body, and HTTP method (defaulting to POST). The function will handle setting up the web request and disposing of resources appropriately.

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Step 2: Initialize the Web Request

Inside the function, create the WebRequest object, set the request properties, and write the body if the method is POST:

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Step 3: Retrieve the Response

After sending the request, capture and read the response from the server. Make sure to handle any potential exceptions and dispose of the resources safely:

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Step 4: Usage Example

Now that our function is ready, you can call it like this:

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Conclusion

By creating a custom function like InvokeRest, you can replicate the functionality of Invoke-RestMethod in PowerShell 2.0. This solution not only helps you perform POST requests but also gives you a deeper understanding of how .NET handles web requests under the hood. Now you're well-equipped to interact with APIs even without modern cmdlets at your disposal.

Don't hesitate to experiment with the code and adjust the parameters according to your specific needs!