Update .NET Framework Target Version in Legacy and SDK Project Formats

UpdateDotNetTargetVersion.ps1

# This script updates .NET Target Framework version in both SDK and Legacy Project format types. 

using namespace System.Collections.Generic

# Provide the src folder where the csproj files are located. 
# This script can check the child folders as well.
$dir = "C:\Helix\src"

# Provide the target framework version
$legacyTargetFrameworkVersion = "v4.7.2";
$sdkTargetFrameworkVersion = "net472";

$projFiles = Get-ChildItem $dir -Recurse -Filter *.csproj

$projsWithVersion = [List[object]]::new()

foreach($file in $projFiles)
{
    $content = [xml](Get-Content $file.FullName)
    $legacyVersionNodes = $content.GetElementsByTagName("TargetFrameworkVersion");
    $sdkVersionNodes = $content.GetElementsByTagName("TargetFramework");
    $projectType = 0

    if ($legacyVersionNodes.Count -eq 1)
    {
        # Legacy
        $projectType = 1
    }
    elseif ($sdkVersionNodes.Count -eq 1)
    {
        # SDK
        $projectType = 2
    }
    else 
    {
        Write-Host "The project has no framework version node: $file.FullName"
    }
        
    switch($projectType)
    {
        0 {
            Write-Host "The project has no framework version: $file.FullName"
            break;
        }
        1 {
            # Legacy
            $version = $legacyVersionNodes[0].InnerText;

            $projsWithVersion.Add([PsCustomObject]@{
                File = $file;
                XmlContent = $content;
                VersionNode = $legacyVersionNodes[0];
                VersionRaw = $version;
                ProjectType = "Legacy";
            })

            break;
        }
        2 {
            # SDK
            $version = $sdkVersionNodes[0].InnerText;

            $projsWithVersion.Add([PsCustomObject]@{
                File = $file;
                XmlContent = $content;
                VersionNode = $sdkVersionNodes[0];
                VersionRaw = $version;
                ProjectType = "SDK";                
            })

            break;
        }
        default {
            Write-Host "Could not change the framework version: $file.FullName"
            break;
        }
    }
}

# Loop through each list item and update the project. 
foreach($proj in $projsWithVersion)
{    
    # If the project framework version is already beyond the target version, it will be skipped. 
    if ($proj.ProjectType -eq "Legacy") {
        $proj.VersionNode.set_InnerXML("$legacyTargetFrameworkVersion")
        $proj.XmlContent.Save($proj.File.FullName);
    }
    elseif ($proj.ProjectType -eq "SDK") {         
        $proj.VersionNode.set_InnerXML("$sdkTargetFrameworkVersion")
        $proj.XmlContent.Save($proj.File.FullName);
    }
}

# Reference: https://www.thinktecture.com/en/net/bulk-update-of-net-framework-version-powershell/