CODEWITHSUNDEEP
c#dependency-injectionninject
Mames
Mames

Reputation: 85

Constructor injection - binding two separate configuration dependencies into a repository class

What is the best practice, following DI, to create two separate repository classes...e.g.

public class FirstDbRepo : Repository

public class SecondDbRepo : Repository

That essentially implement the Repository class shown below

namespace MyApp.Persistence
{
    public class Repository<T> : IRepository<T> where T : EntityBase
    {
        public IConfig Config { get; set; }
        private Database Database 
        { 
            get 
            {
                 // Use Config to get connection
            }; 
            set; 
        }

        public Repository(IConfig config)
        {
            Config = config;
        }

        public IEnumerable<T> Get(Expression<Func<T, bool>> predicate)
        {
            // Use database to get items
        }

        public T CreateItem(T item)
        {
            // Use database to create item
        }
    }
}

But to inject different config values/instances...

public interface IConfig
{
    string DatabaseName{ get; }
    string DatabaseEndpoint{ get; }
    string DatabaseAuthKey{ get; }
}

The first thing I thought of was to create marker interfaces, but wanted to know if this smells...is there a more correct way to do this using DI?

public interface IFirstDbRepo { }

public class FirstDbRepo<T> : Repository<T> where T: EntityBase
{
    public FirstDbRepo(FirstConfig config)
        : base(config)
    { }
}

public class FirstConfig : IConfig
{
    public string DatabaseName{ get { return "MyName" }; } // From web.config
}

And then use a ninject binding for each repo...the consumer could use as follows

public class Consumer() {
     private readonly IFirstDbRepo _firstRepo;
     public Consumer(IFirstDbRepo firstRepo) {
         _firstRepo = firstRepo;
     }
}

Upvotes: 1

Views: 94

Answers (1)

Scott Hannen
Scott Hannen

Reputation: 29207

Bind<IConfig>().To<MyConfigOne>().WhenInjectedInto(typeof(FirstDbRepo));
Bind<IConfig>().To<MyConfigTwo>().WhenInjectedInto(typeof(SecondDbRepo ));

Contextual binding

Upvotes: 1

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