PowerShell array to store strings

Question

I have a list of files that I am breaking up into parts. That works, but I want to be able to reference each part individually. The issue is with my array not wanting/being able to take in a string. The file naming format is custID_invID_prodID or custID_invID_prodID_Boolvalue.

$files = Get-ChildItem test *.txt
[string]$custId = $files.Count
[string]$invID = $files.Count
[string]$prodID = $files.Count
[int]$Boolvalue = $files.Count
foreach($file in (Get-ChildItem test *.txt)) {
    for($i = 0; $i -le $files.Count; $i++){
        $custId[$i], $invID[$i], $prodID[$i], $Boolvalue[$i] = $file.BaseName -split "_"
        Write-Host $custId, $invID, $prodID, $Boolvalue
    }
}

The error message I am seeing is:

Unable to index into an object of type System.String.

How can I do this?

I just updated my post lol. The file format is listed now. I am taking all the files and breaking them up into sections based upon "_" and saving each chuck as a variable so I can use it in other places — Grady D
– Grady D, Commented Feb 19, 2014 at 15:32

Robert Westerlund · Accepted Answer · 2014-02-19 16:57:08Z

I'd suggest working with objects instead of a lot of string arrays. I have an example below in which I have replaced the file listing, since I don't have the file structure in place, with an ordinary array. Just remove that array declaration and put in your Get-ChildItem call and it should work just fine.

function ConvertTo-MyTypeOfItem
{
    PARAM (
        [ValidatePattern("([^_]+_){3}[^_]+")]
        [Parameter(Mandatory = $true, ValueFromPipeline = $true)]
        [string]$StringToParse
    )

    PROCESS {
        $custId, $invId, $prodId, [int]$value = $StringToParse -split "_"
        $myObject = New-Object PSObject -Property @{
            CustomerID = $custId;
            InvoiceID = $invId;
            ProductID = $prodId;
            Value = $value
        }
        Write-Output $myObject
    }
}

# In the test scenario I have replaced getting the list of files
# with an array of names. Just uncomment the first and second lines 
# following this comment and remove the other $baseNames setter, to
# get the $baseNames from the file listing

#$files = Get-ChildItem test *.txt
#$baseNames = $files.BaseName
$baseNames = @(
    "cust1_inv1_prod1_1";
    "cust2_inv2_prod2_2";
    "cust3_inv3_prod3_3";
    "cust4_inv4_prod4_4";
)

$myObjectArray = $baseNames | ConvertTo-MyTypeOfItem 

$myObjectArray

The above function will return objects with the CustomerID, InvoiceID, ProductID and Value properties. In the sample above, the function is called and the returned array value is set to the $myObjectArray/code> variable. When output in the console it will give the following output:

InvoiceID                CustomerID               ProductID                                  Value
---------                ----------               ---------                                  -----
inv1                     cust1                    prod1                                          1
inv2                     cust2                    prod2                                          2
inv3                     cust3                    prod3                                          3
inv4                     cust4                    prod4                                          4

AdamL · Accepted Answer · 2014-02-19 16:09:07Z

1

Seems to me that you're doing it the hard way. Why 4 arrays for every "field" of a file? It's better to create array of arrays - first index would indicate a file, and second a field in file:

$files = Get-ChildItem test *.txt

$arrFiles = @(,@());
foreach($file in $files ) {
    $arrFile = $file.BaseName -split "_"
    $arrFiles += ,$arrFile;
}
Write-Host "listing all parts from file 1:"
foreach ($part in $arrFiles[1]) {
    Write-Host $part
}
Write-Host "listing part 0 from all files":
for ($i=0; $i -lt $arrFiles.Count ; $i++) {
    Write-Host $arrFiles[$i][0];
}

answered Feb 19, 2014 at 16:09

AdamL

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3 Comments

AdamL Over a year ago

@aDroidman Well, then it's not that great after all, is it? :). Did you try to estimate how many files would have to be there to cause such problems?

Grady D Over a year ago

I did and it comes down to file size. It could be 700 files or 50.

AdamL Over a year ago

@aDroidman What does file size have to do with it? I'm not reading file contents, but file names...

arco444 · Accepted Answer · 2014-02-19 16:10:17Z

Because you're trying to index into an object of type System.String! You set all your variables as strings to start with and then try to assign to an index, which I presume would attempt to assign a string to the character position at the index you provide.

This is untested but should be in the right direction.

$custIdArr = @()
$invIDArr = @()
$prodIDArr = @()
$BoolvalueArr = @()
foreach($file in (Get-ChildItem test*.txt)) {
    $split = $file.BaseName -split "_"
    $custId = $split[0];  $custIdArr += $custId
    $invID = $split[1];  $invIDArr += $invId
    $prodID = $split[2];  $prodIDArr += $prodID
    $boolValue = $split[3];  $boolValueArr += $boolValue
    Write-Host $custId, $invID, $prodID, $Boolvalue
}

Create a set of empty arrays, loop through your directory, split the filename for each file, append the results of the split into the relevant array.

I'm assigning to $custId, $invID, $prodID, $Boolvalue for the sake of clarity above, you may choose to directly add to the array from the $split var i.e. $invIDArr += $split[1]

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