Method GetDirectory

Namespace: IOInfoExtensions

Assembly: IOInfoExtensions.dll

GetDirectory(DirectoryInfo, string, bool, bool)

Returns a DirectoryInfo object for a child directory with the specified name.

public static DirectoryInfo GetDirectory(this DirectoryInfo directory, string name, bool resolve = false, bool ignoreCase = false)

Remarks

Creates a new DirectoryInfo object referencing a child directory of the calling object. The newly created DirectoryInfo object will have the given name and be validated against the remaining parameters.

Specifying nested directories in name is supported.

Parameters

directory DirectoryInfo: The calling DirectoryInfo object that will be the parent of the returned DirectoryInfo object.
name string: The name of the child directory to return.
resolve bool: If set to true the child directory's existance will be validated.
ignoreCase bool: If set to true the search for the child directory will be case in-sensitive.

Returns

DirectoryInfo: System.IO.DirectoryInfo referencing the desired child directory.

Examples

Example 1

Get an existing child directory.

var demoRoot = new DirectoryInfo("C:\\Demo");

Console.WriteLine("First level children:");
demoRoot.GetFileSystemInfos().ToList().ForEach(x => Console.WriteLine($"\t{x.FullName}"));

var child = demoRoot.GetDirectory("ChildDir1");
Console.WriteLine($"Child FullName:\n\t{child.FullName}");
Console.WriteLine($"Child Type:\n\t{child.GetType()}");
Console.WriteLine($"Child Exists:\n\t{child.Exists}");

/*
Output:
First level children:
        C:\Demo\ChildDir1
        C:\Demo\ChildDir2
        C:\Demo\ChildFile1.txt
        C:\Demo\ChildFile2.txt
Child FullName:
        C:\Demo\ChildDir1
Child Type:
        System.IO.DirectoryInfo
Child Exists:
        True
*/

$directory = New-Object System.IO.DirectoryInfo 'C:\Demo'

Write-Host "First level children:"
$directory.GetFileSystemInfos().FullName | ForEach-Object { Write-Host "`t$_" }

$child = $directory.GetDirectory('ChildDir1')
Write-Host "Child FullName:`n`t$($child.FullName)"
Write-Host "Child Type:`n`t$($child.GetType().FullName)"
Write-Host "Child Exists:`n`t$($child.Exists)"

<#
Output:
First level children:
        C:\Demo\ChildDir1
        C:\Demo\ChildDir2
        C:\Demo\ChildFile1.txt
        C:\Demo\ChildFile2.txt
Child FullName:
        C:\Demo\ChildDir1
Child Type:
        System.IO.DirectoryInfo
Child Exists:
        True
#>

This returns a DirectoryInfo object for the child directory named ChildDir1. It uses default values for the resolve and ignoreCase parameters.

Example 2

Get a non-existing nested child directory.

var demoRoot = new DirectoryInfo("C:\\Demo");

Console.WriteLine("Children:");
demoRoot.GetFileSystemInfos("*", SearchOption.AllDirectories)
    .ToList()
    .ForEach(x => Console.WriteLine($"\t{x.FullName}"));

var child = demoRoot.GetDirectory("ChildDir3\\InnerChildDir3");
Console.WriteLine($"Child FullName:\n\t{child.FullName}");
Console.WriteLine($"Child Type:\n\t{child.GetType()}");
Console.WriteLine($"Child Exists:\n\t{child.Exists}");

/*
Output:
Children:
        C:\Demo\ChildDir1
        C:\Demo\ChildDir2
        C:\Demo\ChildFile1.txt
        C:\Demo\ChildFile2.txt
        C:\Demo\ChildDir2\ChildFile1.txt
        C:\Demo\ChildDir2\ChildFile2.txt
Child FullName:
        C:\Demo\ChildDir3\InnerChildDir3
Child Type:
        System.IO.DirectoryInfo
Child Exists:
        False
*/

$directory = New-Object System.IO.DirectoryInfo 'C:\Demo'

Write-Host "Children:"
$directory.GetFileSystemInfos("*", [System.IO.SearchOption]::AllDirectories).FullName |
    ForEach-Object { Write-Host "`t$_" }

$child = $directory.GetDirectory('ChildDir3\InnerChildDir3')
Write-Host "Child FullName:`n`t$($child.FullName)"
Write-Host "Child Type:`n`t$($child.GetType().FullName)"
Write-Host "Child Exists:`n`t$($child.Exists)"

<#
Output:
Children:
        C:\Demo\ChildDir1
        C:\Demo\ChildDir2
        C:\Demo\ChildFile1.txt
        C:\Demo\ChildFile2.txt
        C:\Demo\ChildDir2\ChildFile1.txt
        C:\Demo\ChildDir2\ChildFile2.txt
Child FullName:
        C:\Demo\ChildDir3\InnerChildDir3
Child Type:
        System.IO.DirectoryInfo
Child Exists:
        False
#>

This returns a DirectoryInfo object for the nested child directory named ChildDir3\InnerChildDir3. It uses default values for the resolve and ignoreCase parameters.

Example 3

Resolve a child directory using case sensitivity.

var demoRoot = new DirectoryInfo("C:\\Demo");

Console.WriteLine("First level children:");
demoRoot.GetFileSystemInfos().ToList().ForEach(x => Console.WriteLine($"\t{x.FullName}"));

try
{
    _ = demoRoot.GetDirectory("childdir1", true, false);
}
catch (Exception ex)
{
    var stringArgs = new[] {
        ex.GetType().ToString(),
        ex.Message,
        ex.StackTrace.Substring(0, ex.StackTrace.IndexOf(Environment.NewLine))
    };

    Console.Error.WriteLine(string.Format("\nError: {0}: {1}\n{2}\n", stringArgs));
}

/*
Output:
First level children:
        C:\Demo\ChildDir1
        C:\Demo\ChildDir2
        C:\Demo\ChildFile1.txt
        C:\Demo\ChildFile2.txt

Error: System.IO.DirectoryNotFoundException: A child named 'childdir1' already exists but with a different case: ChildDir1.
    at IOInfoExtensions.DirectoryInfoExtensions.GetDirectory(DirectoryInfo directory, String name, Boolean resolve, Boolean ignoreCase)
*/

$directory = New-Object System.IO.DirectoryInfo 'C:\Demo'

Write-Host "First level children:"
$directory.GetFileSystemInfos().FullName | ForEach-Object { Write-Host "`t$_" }

try
{
    $null = $directory.GetDirectory('childdir1', $true, $false)
}
catch
{
    $stringArgs = @(
        $_.Exception.GetType().ToString(),
        $_.Exception.Message,
        $_.Exception.StackTrace.Substring(0, $_.Exception.StackTrace.IndexOf([Environment]::NewLine))
    )

    Write-Host ("`nError: {0}: {1}`n{2}`n" -f $stringArgs)
    $error.Clear()
}

<#
Output:
First level children:
        C:\Demo\ChildDir1
        C:\Demo\ChildDir2
        C:\Demo\ChildFile1.txt
        C:\Demo\ChildFile2.txt

Error: System.IO.DirectoryNotFoundException: A child named 'childdir1' already exists but with a different case: ChildDir1.
    at IOInfoExtensions.DirectoryInfoExtensions.GetDirectory(DirectoryInfo directory, String name, Boolean resolve, Boolean ignoreCase)
#>

Throws an exception because the existance and case sensitivity validations failed.

Exceptions

ArgumentException: If the name parameter value is null, empty, or just whitespace.
Exception: If the name matched multiple child items. This will happen if a wildcard was passed as part of the name.
DirectoryNotFoundException: If the name resolves to a child file, resolve is set to true and the child directory does not exist, or if ignoreCase is set to false and the casing doesn't match.

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