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Lamar 5.0.0





Getting Started

This page does assume that you are already familiar with IoC containers. For more background on the concepts and usage of an IoC container within your application, see Software Design Concepts

Lamar is a .Net library that provides two pieces of functionality:

  1. A fast Inversion of Control Container that natively supports the ASP.Net Core DI abstractions and a subset of the older StructureMap library
  2. The dynamic code generation and compilation features used underneath the IoC implementation

Lamar as IoC Container

To get started, just add Lamar to your project through Nuget.

Most of the time you use an IoC container these days, it's probably mostly hidden inside of some kind of application framework. However, if you wanted to use Lamar all by itself you would first bootstrap a Lamar container with all its service registrations something like this:

var container = new Container(x =>
    // Using StructureMap style registrations
    // Using ASP.Net Core DI style registrations
    x.AddTransient<IClock, Clock>();
    // and lots more services in all likelihood

Now, to resolve services from your container:

// StructureMap style

// Get a required service
var clock = container.GetInstance<IClock>();

// Try to resolve a service if it's registered
var service = container.TryGetInstance<IService>();

// ASP.Net Core style
var provider = (IServiceProvider)container;

// Get a required service
var clock2 = provider.GetRequiredService<IClock>();

// Try to resolve a service if it's registered
var service2 = provider.GetService<IService>();

Definitely note that the old StructureMap style of service resolution is semantically different than ASP.Net Core's DI resolution methods. That's been the cause of much user aggravation over the years.

Lamar within ASP.Net Core Applications

To use Lamar within ASP.Net Core applications, also install the Lamar.Microsoft.DependencyInjection library from Nuget to your ASP.Net Core project (and you can thank Microsoft for the clumsy naming convention, thank you).

With that Nuget installed, your normal ASP.Net Core bootstrapping changes just slightly. When you bootstrap your IWebHostBuilder object that configures ASP.Net Core, you also need to call the UseLamar() method as shown below:

public static void Main(string[] args)
    var builder = new WebHostBuilder();
        // Replaces the built in DI container
        // with Lamar
        // Normal ASP.Net Core bootstrapping



If you use a StartUp class for extra configuration, your ConfigureContainer() method can take in a ServiceRegistry object from Lamar for service registrations in place of the ASP.Net Core IServiceCollection interface as shown below:

public class Startup
    // Take in Lamar's ServiceRegistry instead of IServiceCollection
    // as your argument, but fear not, it implements IServiceCollection
    // as well
    public void ConfigureContainer(ServiceRegistry services)
        // Supports ASP.Net Core DI abstractions
        // Also exposes Lamar specific registrations
        // and functionality
        services.Scan(s =>

    public void Configure(IApplicationBuilder app)

You can also still write ConfigureServices(IServiceCollection), but you'd miss out on most of Lamar's extra functionality beyond what that abstraction provides.

And that is that, you're ready to run your ASP.Net Core application with Lamar handling service resolution and object cleanup during your HTTP requests.

Lamar for Runtime Code Generation & Compilation

Please see LamarCodeGeneration & LamarCompiler for more information.