Simple And Best Way of Implementing the Repository Pattern

What is Repository Pattern?

I have seen so many ways to write repository pattern. I have read Rob Conery's blog also.

But, according to my experience, the repository pattern is the one constructing criteria by client code and passing it to repository.

A repository is nothing but a mediator between data access layer and business layer.

I will try to explain in a very simplest method to understand repository pattern.

Step 1:

Create VS 2010 project and name it RepPattern.

I have created here a Silverlight application. Because I really like to work with Silverlight.




In this application, I have added two folders.

1. Contract:
   
   To hold all interface entity.
   
   That is IPattern interface.
    
2. Service:
   
   To hold all interface implemented class.
   
   That is PatternService class.

Step 2:

In IPattern interface, I have declared signature to get some value. I. e Get default name.

At the same time I have implemented IPattern interface on PatternService class as given below.



These modules belongs to the repository.

Step 3:

Now, it's the time to actually implement this repository.

Here I have added one more class called PatternHelper.cs. Also, I have written one static method to return all repository methods.



Step 4:

Next one is calling these repository methods from client.



Step 5:

Run the application.



As I said before, repository is nothing but a mediator between business logic and data access layer.

Here, PatternHelper works as repository layer.

These separation of business logic and data helps in three ways.

• It centralizes the data logic or Web service access logic.
• It provides a substitution point for the unit tests.
• It provides a flexible architecture that can be adapted as the overall design of the application evolves.

Usage of Repository pattern:

1. We can use this pattern to access a data source from many locations yet centrally manage the data source.
2. We can test it individually (Unit test).
3. Code maintainability. 

Thanks
Enjoy the coding!!!!!