Maybe the header is wrong but i dont know how to explain.
I have 4 csv files with aprox 15000 rows in each looking like this

number,”surname”,”forename”,”emailAddress”,”taxIdentifier”
100238963,”Smith”,”John”,”[email protected]”,”xxxxxxxxxxxx”

Im reading in 9999 of the rows and creating a json file we use on a site to check every person, we then get a respond back for most of the users, and that respons is “number”
Then i need to find all them persons in the first array.
I have done it like this today, but it take to much time to check every person like this, is there any better way of doing this?

This is the code for getting the persons from the file and create json file:

$Files = Get-ChildItem -Path "$Folders\\*" -Include *.csv -Force

foreach ($File in $Files){
    $fname = $file
    $fname = (Split-Path $File.name -leaf).ToString().Replace(".csv", "")
    $Savefile = $fname+ "_Cleaned.csv"

        $users = Import-Csv $File
        $body = "{`"requestId`": `"144x25`",`"items`": ["
 
$batchSize = 9999
$batchNum = 0
$row = 0
while ($row -lt $users.Count) {
    $test = $users[$row..($row + $batchSize - 1)]

foreach ($user in $test) {

    $nr = $user.number
    $tax = $user.taxIdentifier
    $body += "{`"itemId`": `"$nr`",`"subjectId`": `"$tax`"},"
}

And then this is the code to deal with the respons:

       $Result = @()

foreach ($1 in $response.allowedItemIds)
{
    foreach ($2 in $Users){

        If ($2.number -like $1)
        {
            $Result += [pscustomobject]@{
            number = $2.number
            Surname = $2.surname
            Forename = $2.forename
            Email = $2.emailaddress
            Taxidendifier = $2.taxIdentifier

        }
    }

}

}
$Result | Export-Csv -path "$folders\$savefile" -NoTypeInformation -Append
    $row += $batchSize
    $batchNum++

Hope someone has any ideas

Cheers