Odtnhj

I have the requirement to be able to perform many conversions of external models to my own internal models.

I have decided to apply the Adapter pattern, but I want to make it as generic as possible. So effectively, I want it to be handle both "single" POCO's, but if i need to pass/adapt a collection then this also must work eg:

IEnumerable<IAdaptee> OR IList<TAdaptee>

and return my own adapted object(s):

IEnumerable<IAdapted> OR IList<TAdapted>

I want to do something like the following:

public interface IGenericAdapter

 TAdapted Adapt<TAdapted,TAdaptee>(TAdaptee adaptee);

Where I am coming unstuck is when I build my "Adapter" class, and then implement the above interface, I am getting constraint mismatch errors. This of course, makes sense, because If i am applying constraints to the classes which implement the interface, and the interface doesn't have them, then of course errors occur.

So:

public class AToBAdapter

public TAdapted Adapt<TAdapted,TAdaptee>(TAdaptee adaptee)
where TAdapted: IList<FooAdapted>
where TAdaptee: IList<FooAdaptee>

// I want my constraints to be active here, as I need to perform specific operations here

The above works fine in and of itself, which is fine. But I want to hide all this behind a generic interface that I can use whenever it suits.

Of course, Once i add this it fails due to no constraints on the interface, yet constraints on the implementing class.

public class AToBAdapter:IAdapterGeneric

What's the magic bullet here which will enable me to build a truly generic Adapter - I'm guessing certain constraints on the interface? casting? but need assistance on the best course of action.

Thanks,
Chud

If you have access to your external models, you could use an interface as a marker:

public interface IAdaptee 
public interface IAdapted 

And use those interfaces as your adapter interface constraints:

public interface IGenericAdapter<out TAdapted, in TAdaptee>
 where TAdaptee : IAdaptee
 where TAdapted : IAdapted

 TAdapted Adapt(TAdaptee adaptee);

You could pass this adapter into a helper method for adapting multiple objects (assuming the adapt logic stays the same for multiple):

public IEnumerable<TAdapted> AdaptMultiple<TAdapted, TAdaptee>
 (IEnumerable<TAdaptee> adaptees, IGenericAdapter<TAdapted, TAdaptee> adapter)
 where TAdaptee : IAdaptee
 where TAdapted : IAdapted

 return adaptees.Select(adapter.Adapt);

For example, we can construct the following concrete classes:

public class ConcreteAdaptee : IAdaptee 

public class ConcreteAdapted : IAdapted 

public class ConcreteAdapter : IGenericAdapter<ConcreteAdapted, ConcreteAdaptee>

 public ConcreteAdapted Adapt(ConcreteAdaptee adaptee)
 
 // Adapt Logic

 return new ConcreteAdapted();
 

And adapt them as such:

IGenericAdapter<ConcreteAdapted, ConcreteAdaptee> adapter = new ConcreteAdapter();

var adaptee = new ConcreteAdaptee();
var adapted = adapter.Adapt(adaptee);

var adaptees = new List<ConcreteAdaptee>();
var adapteds = AdaptMultiple(adaptees, adapter);

consider the following example :

interface IDog

 void Bark();


interface ICat

 void Meow();

class SomeDog : IDog

 public void Bark()
 
 Console.WriteLine(@"bark bark");
 


class SomeCat : ICat

 public void Meow()
 
 Console.WriteLine(@"meow meow");
 


class CatToDogAdapter : IDog

 private ICat cat;
 public CatToDogAdapter(ICat cat)
 
 this.cat = cat;
 

 public void Bark()
 
 cat.Meow();
 


new Dog().Bark(); // bark bark
new CatToDogAdapter().Bark();// meow meow

this is how adapter works.

Let say you have a model MyAdaptedData and you recive data containing HotelName, Name,PropertyName from agoda , booking and tripadviser
for each booking model you need to write adapter

AgodaAdapter : MyAdaptedData
 public AgodaAdapter(AgodaModel agodaModel)
 ....
 
 public stirng HotelName
 get
 return agodaModel.HotelNamebyAgoda;
 
 
 ....

Same for booking and tripadvisor.
Adapter pattern helps you to retrieve necessary data from external models.

Then you need to create specific adapter depending on the adaptee type. Use Factory method pattern

MyAdaptedData AdaptersFactory(object adaptee)

 if(adaptee is AgodaModel)
 return new AgodaAdapter(adaptee);
 ....
 if(adaptee is XBookingModel)
 return new XBookingAdapter(adaptee);