CODEWITHSUNDEEP
c#dependency-injectioninversion-of-controlninject
void
void

Reputation: 43

How do I provide extra parameters with Ninject?

I need to auto-resolve dependencies of my windows form. The only problem is my forms constructor expects an integer value as well. Please have a look at the implementation in the code section.

   //Ninject bindings
   public class Bindings : NinjectModule
    {
        public override void Load()
        {
            Bind<ILogger>().To<LogToDB>();
            Bind<ICopy>().To<CopyToFolder>();            
        }
    }

  //WinForm - Form1
   public partial class Form1 : Form
    {
        public readonly ILogger _processRepository;
        public readonly Icopy _copy;
        public readonly int ValueToEdit;
        public Form1(int valueToEdit, ILogger logger, ICopy copy)
        {
            this._processRepository = logger;
            this._copy = copy;
            this.ValueToEdit = valueToEdit;
            InitializeComponent();
        }
    }
    //main
    /// <summary>
    /// The main entry point for the application.
    /// </summary>
    [STAThread]
    static void Main()
    {
        IKernel kernel = new StandardKernel(new Bindings());            
        Application.Run(kernel.Get<Form1>());            
    }

I get an error: Ninject.ActivationException: 'Error activating int No matching bindings are available, and the type is not self-bindable.

How can I auto resolve the form dependencies and also be able to pass the integer value? Actually, I have used the same form for add and edit purpose so while editing, this edit value should be set.

Upvotes: 1

Views: 678

Answers (2)

void
void

Reputation: 43

using Ninject;
using Ninject.Modules;
using Ninject.Parameters;  
//Add new class  
public class CompositionRoot
{
    public static IKernel _ninjectKernel;
    public static void Wire(INinjectModule module)
    {
        _ninjectKernel = new StandardKernel(module);
    }
    public static T Resolve<T>()
    {
        return _ninjectKernel.Get<T>();
    }
    public static T ResolveWithArgument<T>(ConstructorArgument argument)
    {
        return _ninjectKernel.Get<T>(argument);
    }
}

//Ninject bindings
public class Bindings : NinjectModule
{
    public override void Load()
    {
        Bind<ILogger>().To<LogToDB>();
        Bind<ICopy>().To<CopyToFolder>();            
    }
}

//WinForm - Form1
public partial class Form1 : Form
{
    public readonly ILogger _processRepository;
    public readonly Icopy _copy;
    public readonly int ValueToEdit;
    public Form1(ILogger logger, ICopy copy, int valueToEdit)
    {
        this._processRepository = logger;
        this._copy = copy;
        this.ValueToEdit = valueToEdit;
        InitializeComponent();
    }
}

//main
/// <summary>
/// The main entry point for the application.
/// </summary>
[STAThread]
static void Main()
{
   //Apply the binding rule first
   CompositionRoot.Wire(new Bindings());   
   //Then resolve your form dependencies this way using Ninject passing along the 
   constructor arguments. 
   CompositionRoot.ResolveWithArgument<Form1>(new ConstructorArgument("valueToEdit", 
   1)).ShowDialog();      
}

Upvotes: 0

Georg
Georg

Reputation: 5790

I guess the cleanest way to solve this problem is to create a factory:

interface IForm1Factory
{
    Form1 Create(int valueToEdit);
}

class Form1Factory
{
    public readonly ILogger _processRepository;
    public readonly Icopy _copy;

    public Form1Factory(ILogger logger, ICopy copy)
    {
        this._processRepository = logger;
        this._copy = copy;
    }

    public Form1 Create(int valueToEdit)
    {
        return new Form1(valueToEdit, _processRepository, _copy);
    }
}

There is also an extension (Ninject.Extensions.Factory) that allow you to auto-generate factories such as the Form1Factory based on the interface. If you use that extension, you declare that using Bind<IForm1Factory>().ToFactory().

Upvotes: 3

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