invoke-webrequest gives different object for header property in PS 5.1 vs PS CORE 7.1

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I'm getting mixed output between same piece of running code on PS 5.1 and PS Core 7.1

PS 5.1

get-host


Name             : Windows PowerShell ISE Host
Version          : 5.1.17763.2268

$response = Invoke-WebRequest google.com
$response.headers

Key               Value                                                                                         
---               -----                                                                                         
X-XSS-Protection  0                                                                                             
X-Frame-Options   SAMEORIGIN                                                                                    
Vary              Accept-Encoding                                                                               
Transfer-Encoding chunked                                                                                       
Accept-Ranges     none                                                                                          
Cache-Control     private, max-age=0       


Name             : ConsoleHost
Version          : 7.1.3

$response = Invoke-WebRequest google.com
PS C:\> $response.headers

Key               Value
---               -----
Date              {Tue, 14 Dec 2021 15:41:47 GMT}
Cache-Control     {max-age=0, private}
P3P               {CP="This is not a P3P policy! See g.co/p3phelp for more info."}
Server            {gws}

I tried the usebasicparsing on the 5.1 instance, same result as above. Why am I getting this strange object from the powershell core commandlet? I have to convert the properties to string to get them to work equally well on PS core.

Am I doing something wrong?

thanks, ionut

invoke-webrequest powershell-core powershell
1 Answers

You are doing nothing wrong.

If you look at the Invoke-WebRequest documentation you will see that they return either a BasicHtmlWebResponseObject (powershell core) or a HtmlWebResponseObject (windows powershell).

In both cases the header is a WebResponseObject.Headers object, which is a Dictionary<String,IEnumerable<String>>

My guess is that Windows Powershell is converting the IEnumerable<String> to a string before returning it, while Powershell Core is keeping the underlying .NET type.

In your case you can convert the headers in every case to strings with e.g.:

$response.Headers.GetEnumerator() | ForEach-Object { $_.Value -join "," }

Windows Powershell and Powershell Core are similar enough, but not 100% compatible, so you will always find cases like this where you have differences that you have to take care of if you want to support both versions.

user_18607570
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