PowerShell v3 Invoke-WebRequest: Troubles with forms

Question

Since I upgraded to Windows 8 a lot of my PowerShell scripts relying on launching an invisible IE won’t quite work anymore, so I tried switching to the Invoke-WebRequest

Answer 1

Try doing the post directly e.g.:

$formFields = @{username='john doe';password='123'}
Invoke-WebRequest -Uri $myUrl -Method Post -Body $formFields -ContentType "application/x-www-form-urlencoded"

Answer 2

If you're me and have been troubleshooting a bad Web Request, in my case a -Body that was becoming null at my API, then you will want to know about the gotcha that is about interleaving your line continuations with comments. This

$r = iwr -uri $url `
    -method 'POST' `
    -headers $headers `
    # -contenttype 'application/x-www-form-urlencoded' ` # default
    -Body $body

Notice the commented out line # -contenttype 'application/x-www-form-urlencoded' # default

Putting a comment truncates the remaining back-ticked line continuation. Therefore, in my case my web request ended up with a request having 0-byte payload.

Answer 3

To address your problem with the unsigned/untrusted certificate, add the line

[System.Net.ServicePointManager]::ServerCertificateValidationCallback = {$true}

before the Invoke-WebRequest statement

Answer 4

The example in the question works, but you have to use rb and not $rb in the first line:

$response = Invoke-WebRequest -Uri $myUrl -Method Default -SessionVariable rb

I also had to use ($myUrl + '/login') since this is my login address.

$response = Invoke-WebRequest -Uri ($myUrl + '/login') -Method Default -SessionVariable rb

And in the last line used ($myUrl + $form.Action):

$response = Invoke-WebRequest -Uri ($myUrl + $form.Action) -WebSession $rb -Method POST