builder-with-arguments.md

Builder with arguments

This example demonstrates how to use builders with custom arguments in dependency injection. It shows how to pass additional parameters during the build-up process.

using Shouldly;
using Pure.DI;

DI.Setup(nameof(Composition))
    .RootArg<Guid>("serviceId")
    .Bind().To<Dependency>()
    .Builder<Service>("BuildUpService");

var composition = new Composition();

var id = Guid.NewGuid();
var service = composition.BuildUpService(new Service(), id);
service.Id.ShouldBe(id);
service.Dependency.ShouldBeOfType<Dependency>();

interface IDependency;

class Dependency : IDependency;

interface IService
{
    Guid Id { get; }

    IDependency? Dependency { get; }
}

record Service: IService
{
    public Guid Id { get; private set; } = Guid.Empty;

    // The Dependency attribute specifies to perform an injection
    [Dependency]
    public IDependency? Dependency { get; set; }

    [Dependency]
    public void SetId(Guid id) => Id = id;
}

Running this code sample locally

• Make sure you have the .NET SDK 9.0 or later is installed

dotnet --list-sdk

• Create a net9.0 (or later) console application

dotnet new console -n Sample

• Add references to NuGet packages
  • Pure.DI
  • Shouldly

dotnet add package Pure.DI
dotnet add package Shouldly

• Copy the example code into the Program.cs file

You are ready to run the example 🚀

dotnet run

Important Notes:

• The default builder method name is BuildUp
• The first argument to the builder method is always the instance to be built
• Additional arguments are passed in the order they are defined in the setup
• Root arguments can be used to provide custom values during build-up

Use Cases:

• When additional parameters are required during object construction
• For scenarios where dependencies depend on runtime values
• When specific initialization data is needed
• For conditional injection based on provided arguments

Best Practices

• Keep the number of builder arguments minimal
• Use meaningful names for root arguments

The following partial class will be generated:

partial class Composition
{
  private readonly Composition _root;

  [OrdinalAttribute(128)]
  public Composition()
  {
    _root = this;
  }

  internal Composition(Composition parentScope)
  {
    _root = (parentScope ?? throw new ArgumentNullException(nameof(parentScope)))._root;
  }

  [MethodImpl(MethodImplOptions.AggressiveInlining)]
  public Service BuildUpService(Service buildingInstance, Guid serviceId)
  {
    if (buildingInstance is null) throw new ArgumentNullException(nameof(buildingInstance));
    Service transientService0;
    Service localBuildingInstance91 = buildingInstance;
    localBuildingInstance91.Dependency = new Dependency();
    localBuildingInstance91.SetId(serviceId);
    transientService0 = localBuildingInstance91;
    return transientService0;
  }
}

Class diagram:

---
 config:
  class:
   hideEmptyMembersBox: true
---
classDiagram
	Dependency --|> IDependency
	Composition ..> Service : Service BuildUpService(Pure.DI.UsageTests.Basics.BuilderWithArgumentsScenario.Service buildingInstance, System.Guid serviceId)
	Service o-- Guid : Argument "serviceId"
	Service *--  Dependency : IDependency
	namespace Pure.DI.UsageTests.Basics.BuilderWithArgumentsScenario {
		class Composition {
		<<partial>>
		+Service BuildUpService(Pure.DI.UsageTests.Basics.BuilderWithArgumentsScenario.Service buildingInstance, System.Guid serviceId)
		}
		class Dependency {
			+Dependency()
		}
		class IDependency {
			<<interface>>
		}
		class Service {
				<<record>>
			+IDependency Dependency
			+SetId(Guid id) : Void
		}
	}
	namespace System {
		class Guid {
				<<struct>>
		}
	}

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