How do you get the response from a 404 page requested from powershell

Question

I have to call an API exposed by TeamCity that will tell me whether a user exists. The API url is this: http://myteamcityserver.com:8080/httpAuth/app/rest/users/monkey

When called from the browser (or fiddler), I get the following back:

Error has occurred during request processing (Not Found).
Error: jetbrains.buildServer.server.rest.errors.NotFoundException: No user can be found by username 'monkey'.
Could not find the entity requested. Check the reference is correct and the user has permissions to access the entity.

I have to call the API using powershell. When I do it I get an exception and I don't see the text above. This is the powershell I use:

try{
    $client = New-Object System.Net.WebClient
    $client.Credentials = New-Object System.Net.NetworkCredential $TeamCityAgentUserName, $TeamCityAgentPassword
    $teamCityUser = $client.DownloadString($url)
    return $teamCityUser
}
catch
{
    $exceptionDetails = $_.Exception
    Write-Host "$exceptionDetails" -foregroundcolor "red"
}

The exception:

System.Management.Automation.MethodInvocationException: Exception calling "DownloadString" with "1" argument(s): "The remote server returned an error: (404) Not Found." ---> System.Net.WebException: The remote server returned an error: (404) Not Found.
   at System.Net.WebClient.DownloadDataInternal(Uri address, WebRequest& request)
   at System.Net.WebClient.DownloadString(Uri address)
   at CallSite.Target(Closure , CallSite , Object , Object )
   --- End of inner exception stack trace ---
   at System.Management.Automation.ExceptionHandlingOps.CheckActionPreference(FunctionContext funcContext, Exception exception)
   at System.Management.Automation.Interpreter.ActionCallInstruction`2.Run(InterpretedFrame frame)
   at System.Management.Automation.Interpreter.EnterTryCatchFinallyInstruction.Run(InterpretedFrame frame)
   at System.Management.Automation.Interpreter.EnterTryCatchFinallyInstruction.Run(InterpretedFrame frame)

I need to be able to check that the page is returned contains the text described above. This way I know whether I should create a new user automatically or not. I could just check for 404, but my fear is that if the API is changed and the call really returns a 404, then I would be none the wiser.

Answer 1

Change your catch clause to catch the more specific WebException, then you can use the Response property on it to get the status code:

{
  #...
} 
catch [System.Net.WebException] 
{
    $statusCode = [int]$_.Exception.Response.StatusCode
    $html = $_.Exception.Response.StatusDescription
}

Answer 2

BrokenGlass gave the answer, but this might help:

try
{
  $URI='http://8bit-museum.de/notfound.htm'
  $HTTP_Request = [System.Net.WebRequest]::Create($URI)
  "check: $URI"
  $HTTP_Response = $HTTP_Request.GetResponse()
  # We then get the HTTP code as an integer.
  $HTTP_Status = [int]$HTTP_Response.StatusCode
} 
catch [System.Net.WebException] 
{
    $statusCode = [int]$_.Exception.Response.StatusCode
    $statusCode
    $html = $_.Exception.Response.StatusDescription
    $html
}
$HTTP_Response.Close()

Response: check: http://8bit-museum.de/notfound.htm 404 Not Found

another approach:

$URI='http://8bit-museum.de/notfound.htm'
try {
  $HttpWebResponse = $null;
  $HttpWebRequest = [System.Net.HttpWebRequest]::Create("$URI");
  $HttpWebResponse = $HttpWebRequest.GetResponse();
  if ($HttpWebResponse) {
    Write-Host -Object $HttpWebResponse.StatusCode.value__;
    Write-Host -Object $HttpWebResponse.GetResponseHeader("X-Detailed-Error");
  }
}
catch {
  $ErrorMessage = $Error[0].Exception.ErrorRecord.Exception.Message;
  $Matched = ($ErrorMessage -match '[0-9]{3}')
  if ($Matched) {
    Write-Host -Object ('HTTP status code was {0} ({1})' -f $HttpStatusCode, $matches.0);
  }
  else {
    Write-Host -Object $ErrorMessage;
  }

  $HttpWebResponse = $Error[0].Exception.InnerException.Response;
  $HttpWebResponse.GetResponseHeader("X-Detailed-Error");
}

if i understand the question then $ErrorMessage = $Error[0].Exception.ErrorRecord.Exception.Message contains the errormessage you are looking for. (source: Error Handling in System.Net.HttpWebRequest::GetResponse() )