Method GetFile

Namespace: IOInfoExtensions

Assembly: IOInfoExtensions.dll

GetFile(DirectoryInfo, string, bool, bool)

Returns a FileInfo object for the child file with the specified name.

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

Remarks

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

Specifying nested files in name is supported.

Parameters

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

Returns

FileInfo: System.IO.FileInfo referencing the desired child file.

Examples

Example 1

Get an existing child file.

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

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

var child = demoRoot.GetFile("ChildFile1.txt");
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\ChildFile1.txt
Child Type:
        System.IO.FileInfo
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 = $directory.GetFile('ChildFile1.txt')
Write-Host "Child FullName:`n`t$($child.FullName)"
Write-Host "Child Type:`n`t$($child.GetType().FullName)"
Write-Host "Child Exists:`n`t$($child.Exists)"

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

This returns a FileInfo object for the child file named ChildFile1.txt. It uses default values for the resolve and ignoreCase parameters.

Example 2

Get a non-existing nested child file.

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

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

var child = demoRoot.GetFile("ChildDir3\\ChildFile3.txt");
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\ChildFile3.txt
Child Type:
        System.IO.FileInfo
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 = $directory.GetFile('ChildDir3\ChildFile3.txt')
Write-Host "Child FullName:`n`t$($child.FullName)"
Write-Host "Child Type:`n`t$($child.GetType().FullName)"
Write-Host "Child Exists:`n`t$($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\ChildFile3.txt
Child Type:
        System.IO.FileInfo
Child Exists:
        False
#>

This returns a FileInfo object for the nested child file named ChildDir3\ChildFile3.txt. It uses default values for the resolve and ignoreCase parameters.

Example 3

Resolve a child file 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.GetFile("childfile1.txt", 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.FileNotFoundException: A child named 'childfile1.txt' already exists but with a different case: ChildFile1.txt.
    at IOInfoExtensions.DirectoryInfoExtensions.GetFile(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.GetFile('childfile1.txt', $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.FileNotFoundException: A child named 'childfile1.txt' already exists but with a different case: ChildFile1.txt.
   at IOInfoExtensions.DirectoryInfoExtensions.GetFile(DirectoryInfo directory, String name, Boolean resolve, Boolean ignoreCase)
#>

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

Exceptions

ArgumentException: If the name 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.
FileNotFoundException: If the name resolves to a child directory, resolve is set to true and the child file does not exist, or if ignoreCase is set to false and the casing doesn't match.

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