C# Create Instance of a Class from string

Overview

Plugin systems and factories often receive type names from configuration. .NET reflection resolves Type objects and constructs instances with Activator.CreateInstance.

Prefer compile-time DI registrations over raw strings when possible.

Implementation

Resolve type: Type.GetType("Namespace.Class, Assembly"). Create: Activator.CreateInstance(type) or with constructor args. In ASP.NET Core, use IServiceProvider.GetRequiredService(type) for DI-managed types.

Handle missing types and constructor exceptions explicitly.

When implementing guidance from C# Create Instance of a Class from string, start in a controlled environment that mirrors production versions of operating systems, runtimes, and network policies. Capture a baseline before changes: export configs, snapshot VMs, or tag releases in source control so rollback stays straightforward if behavior regresses.

Document prerequisites, expected outcomes, and verification steps in a short runbook. Automated checks—smoke tests, health endpoints, or query validations—catch regressions early when platforms receive patches. Security belongs in every workflow: apply least privilege, rotate secrets, and review audit logs after deployment.

If results differ across machines, compare environment variables, permission models, time zones, and regional settings. Intermittent issues often trace to caching layers, stale DNS, or duplicated services bound to the same port.

Example

var typeName = "MyApp.Handlers.EmailHandler, MyApp";
var type = Type.GetType(typeName) ?? throw new InvalidOperationException(typeName);
var instance = (IHandler)Activator.CreateInstance(type)!;
instance.Execute();

Tips

• Whitelist allowed type names for security.
• Use Assembly.LoadFrom for plugin folders.
• Source generators reduce reflection needs.
• Prefer generic factories where types are known.

• Re-verify after reboots, certificate renewals, or failover exercises.
• Align monitoring and alerts with the failure modes described in this guide.
• Keep vendor documentation links handy for breaking changes between versions.
• Pair automation with a manual spot check during initial production rollout.