I'm trying to replace part of a string in Powershell. However, the replacement string is not hardcoded, it's calculated from a function:
$text = "the image is -12345-"
$text = $text -replace "-(\d*)-", 'This is the image: $1'
Write-Host $text
This gives me the correct result: "This is the image: 12345"
Now, I want to include the base64 encoded image. I can read the image from the id. I was hoping the following would work, but it doesn't:
function Get-Base64($path)
{
[convert]::ToBase64String((get-content $path -encoding byte))
}
$text -replace "-(\d*)-", "This is the image: $(Get-Base64 '$1')"
The reason that it doesn't work, is because it first passes $1
(the string, not the value of $1
) to the function, executes it and only then does it do the replace. What I want to do is
You can use the static Replace
method from the [regex]
class:
[regex]::Replace($text,'-(\d*)-',{param($match) "This is the image: $(Get-Base64 $match.Groups[1].Value)"})
Alternatively you can define a regex
object and use the Replace
method of that object:
$re = [regex]'-(\d*)-'
$re.Replace($text, {param($match) "This is the image: $(Get-Base64 $match.Groups[1].Value)"})
For better readability you could define the callback function (the scriptblock) in a separate variable and use that in the replacement:
$callback = {
param($match)
'This is the image: ' + (Get-Base64 $match.Groups[1].Value)
}
$re = [regex]'-(\d*)-'
$re.Replace($text, $callback)