How to escape non-ascii symbols in PowerShell 5.1? - powershell

Question

I'm trying to send a file content to server:
$uri = ...
$headers = #{
...
"Content-Type" = "application/json"
}
[string] $content = Get-Content .\filename -Encoding utf8 -Raw
$body = #{
...
"content" = $content
} | ConvertTo-Json
$response = Invoke-WebRequest $uri -Method 'PUT' -Headers $headers -Body $body
But all of non-ascii symbols are changed to another similar symbols or question marks
How can I escape them?
I've read documentation and I know about parameter -EscapeHandling of cmdlet ConvertTo-Json, but it's available from PowerShell 6.2, I have only 5.1

Answer 1

As a result, I wrote a simple function:
function EscapeNonAscii([string] $s)
{
$sb = New-Object System.Text.StringBuilder;
for ([int] $i = 0; $i -lt $s.Length; $i++)
{
$c = $s[$i];
if ($c -gt 127)
{
$sb = $sb.Append("\u").Append(([int] $c).ToString("X").PadLeft(4, "0"));
}
else
{
$sb = $sb.Append($c);
}
}
return $sb.ToString();
}
And used it like this:
$updateFileResponse = Invoke-WebRequest $updateFileUri -Method 'PUT' -Headers $headers -Body (EscapeNonAscii $body)
It helped. For everybody who will google it in the future, it's a request to GitLab API Update existing file in repository
PS: I use PS as C# because I know it badly. If somebody knows how to rewrite this fragment better please let me know.
PPS: And also I know that StringBuilder.Append changes an existing object, but I add here assigning ($sb = $sb.Append($c) instead of simple $sb.Append($c)) because it prints every action to console. If you know how to fix it please let me know.