How to validate a path string?-CodePudding

Is there any function available to validate a path string?

Microsoft documentation at https://docs.microsoft.com/en-us/dotnet/api/system.io.path?view=net-5.0 says that "All Path members that take a path as an argment throw an ArgumentException if they detect invalid path characters."

Should this throw an exception?

PS C:\src\t> [Io.Path]::GetFullPath('C:\sr<|c\t')
C:\sr<|c\t
PS C:\src\t> dotnet --version
5.0.301
PS C:\src\t> $PSVersionTable.PSVersion.ToString()
7.2.0

CodePudding user response：

Method 1:

We have ValidateScript command to validate the folder path inside the powershell function parameter like below:

function Validate-Path{
   param(
      [parameter(Mandatory)]
      [String]$Path
   )
   if(Test-Path $Path) {Write-Output "Path is valid"}
   else{Write-Output "Path is invalid"}
}

Give this code in the PowerShell and press enter. And type Validate-Path -Path <give-your-folder-path> and press enter which shows valid or invalid path.

I have executed this to validate my folder path in PowerShell: Look at this image (https://i.imgur.com/BHDg1HO.png)

Method 2:

I also tested the zett42 comment and it worked fine:

PS C:\Users\saiha> Test-Path "C:\Users\saiha\Documents"
True
PS C:\Users\saiha> Test-Path "C:\Users\saiha\Docs"
False
PS C:\Users\saiha>

Also With the given path in a question tested with both the methods:

PS C:\Users\saiha> Test-Path "C:\sr<|c\t"
Test-Path : Illegal characters in path.
At line:1 char:1
  Test-Path "C:\sr<|c\t"
  ~~~~~~~~~~~~~~~~~~~~~~
      CategoryInfo          : InvalidArgument: (C:\sr<|c\t:String) [Test-Path], ArgumentException
      FullyQualifiedErrorId : ItemExistsArgumentError,Microsoft.PowerShell.Commands.TestPathCommand

False
PS C:\Users\saiha> Test-Path "C:\src\t"
True
//User-Defined function
PS C:\Users\saiha> function Validate-Path{
>>    param(
>>       [parameter(Mandatory)]
>>       [String]$Path
>>    )
>>    if(Test-Path $Path) {Write-Output "Path is valid"}
>>    else{Write-Output "Path is invalid"}
>> }
PS C:\Users\saiha> Validate-Path -Path C:\src\t
Path is valid
PS C:\Users\saiha> Validate-Path -Path C:\sr<|c\t
c\t : The module 'c' could not be loaded. For more information, run 'Import-Module c'.
At line:1 char:28
  Validate-Path -Path C:\sr<|c\t
                             ~~~
      CategoryInfo          : ObjectNotFound: (c\t:String) [], CommandNotFoundException
      FullyQualifiedErrorId : CouldNotAutoLoadModule

PS C:\Users\saiha>

Practical Screenshot: https://i.imgur.com/ahTsSG3.png

Correct me If I understood in a different.

In Method 1, I created a user-defined function and tested using it and in method 2, Test-Path is a native function. But both do the same checks and give the correct result.

CodePudding user response：

Since apparently the behavior changed dramatically since PS version 5.1, you may have to rely on a test function of your own..

Perhaps something like

function Test-IsValidPath {
    [CmdletBinding()]
    Param(
        [Parameter(Mandatory = $true, Position = 0, ValueFromPipeline = $true, ValueFromPipelineByPropertyName = $true)]
        [Alias('FullName')]
        [string]$Path,
        [switch]$MustExist
    )
    # test for invalid characters
    if ($Path.IndexOfAny([System.IO.Path]::GetInvalidPathChars()) -ge 0) { return $false }
    # if the path should exist
    if ($MustExist) { return (Test-Path -LiteralPath $Path) }
    $true
}

Test-IsValidPath 'C:\sr<|c\t'  # --> False

Of course, you can also create something that would throw exceptions.. For that, please see Which exception should be thrown for an invalid file name?