PPoShTools

0.1.7

Public/Csv/Test-ColumnIsValid.ps1

function Test-ColumnIsValid {

    <#
    .SYNOPSIS
    Validates a column value in a single CSV row.

    .DESCRIPTION
    It is useful in Get-CsvData / Get-ValidationRules to validate columns read from CSV row.
    It returns empty array if the value is valid, or array of error messages if it's invalid.
    
    .EXAMPLE
    $errors += Test-ColumnIsValid -Row $CsvRow -ColumnName 'Login' -NonEmpty -NotContains '?', ' '
    $errors += Test-ColumnIsValid -Row $CsvRow -ColumnName 'Name' -NonEmpty -NotContains '?'
    $errors += Test-ColumnIsValid -Row $CsvRow -ColumnName 'StartDate' -DateFormat 'yyyy-MM-dd'
    $errors += Test-ColumnIsValid -Row $CsvRow -ColumnName 'Gender' -ValidSet '', 'F', 'M'
    #>
    [CmdletBinding()]
    [OutputType([string[]])]
    param(
        # CSV row (or any other PSCustomObject).
        [Parameter(Mandatory = $true)]
        [PSCustomObject]
        $Row,

        # Name of the column which will be validated.
        [Parameter(Mandatory = $true)]
        [string]
        $ColumnName,

        # If $true, it will be asserted the column value is not empty.
        [Parameter(Mandatory = $false)]
        [switch]
        $NonEmpty,

        # If specified, it will be asserted the column value does not contain any of the specified string.
        [Parameter(Mandatory = $false)]
        [string[]]
        $NotContains,

        # If specified, it will be asserted the column value is one of the specified string.
        [Parameter(Mandatory = $false)]
        [string[]]
        $ValidSet,

        # If specified, it will be asserted the column value can be converted to a date using specified format.
        [Parameter(Mandatory = $false)]
        [string]
        $DateFormat
    )

    $errors = @()

    try {
        $value = $Row.$ColumnName
    } catch {
        $value = $null
    }

    if (!$value) {
        if ($NonEmpty) { 
            $errors += "$ColumnName is missing"
        }
        return $errors
    }
    if ($NotContains) {
        foreach ($illegalChar in $NotContains) {
            if ([char[]]$value -icontains $illegalChar) {
                $errors += "$ColumnName has invalid value ('$value') - contains illegal character: '$illegalChar'"
            }
        }
    }
    if ($ValidSet) {
        $ok = $false
        foreach ($validValue in $ValidSet) {
            if ($value -ieq $validValue) {
                $ok = $true
                break
            }
        }
        if (!$ok) {
            $errors += "$ColumnName has invalid value ('$value') - should be one of '{0}'." -f ($ValidSet -join "', ")
        }
    }
    if ($DateFormat) {
        [datetime]$date = New-Object -TypeName DateTime
        $success = [DateTime]::TryParseExact($String, $DateFormat, [System.Globalization.CultureInfo]::InvariantCulture, [System.Globalization.DateTimeStyles]::None, [ref]$date)

        if (!$success) {
            $errors += "$ColumnName has invalid value ('$value') - should be a date in format '$DateFormat'"
        }
    }
    return $errors
}