Sqljob, make powershell step fail if file does not contain certain text - powershell

Question

This is an attempt to get a specific answer to a possible solution to sqljob, on failed step, retry previous step, but not indefinitely
I have a job, which transfer a file using
powershell -command "Invoke-WebRequest https://someserver.dom/fetch.php -OutFile c:/tmp/data.xml"
Sometime the data from upstream is not proper XML. I just want to "grep" for the final line in the file, if it is not the expected </records> I want the step to fail, so the step is retried a few times before it hard-fails.
The filesize could also be a error-criterium. A failed transfer is a few lines, a successfil is megabytes.

Answer 1

So basically i made a function just for this. Set the amount of attempts and the script to run.
function TryAgain($Attempts = 1, $Scriptblock){
while($Attempts -gt 0){
try{
Invoke-Command -ScriptBlock $Scriptblock
Break
}catch{
$_.Exception
$Attempts -= 1
}
}
}
In this case we want to find out if it is valid XML so we are going to get the .RawContent of the Invoke-WebRequest and test against $(new-object System.Xml.XmlDocument).LoadXml(). If it fails throw a error, if it passes then out the raw content to a file. Errors will not be saved to the file only valid XML
$Site = "https://someserver.dom/fetch.php"
$OutFile = "c:/test/data.xml"
(Invoke-WebRequest $Site).RawContent | %{
try{
$(new-object System.Xml.XmlDocument).LoadXml($_)
$_ | out-file $OutFile
}catch{
throw "Bad XML"
}
}
Now we combine into a final product
$Site = "https://someserver.dom/fetch.php"
$OutFile = "c:/test/data.xml"
function TryAgain($Attempts = 1, $Scriptblock){
while($Attempts -gt 0){
try{
Invoke-Command -ScriptBlock $Scriptblock
Break
}catch{
$_.Exception
$Attempts -= 1
}
}
}
TryAgain -Attempts 3 -Scriptblock {
(Invoke-WebRequest $Site).RawContent | %{
try{
$(new-object System.Xml.XmlDocument).LoadXml($_)
$_ | out-file $OutFile
}catch{
throw "Bad XML"
}
}
}
since you dont need the retries and all the glam here is it in basic
(Invoke-WebRequest https://someserver.dom/fetch.php).RawContent | %{
try{
(new-object System.Xml.XmlDocument).LoadXml($_)
$_ | out-file C:\test\test.xml
}catch{}
}