Question

I have a data provider project to access the database. this is composed by various classes (PersonDataProvider, JobDataProvider …)
I want to create an Interface.
Do I have to create an Interface for each class?
I was tempted to create one interface and than inherit on all the classes. This involves making all the projects classes partial and change the classes name…….But i think is not the best solution.
Any suggestion?

Answer 1

You don’t inherit an Interface you implement it. There’s no need to make a class partial to add an interface to it.

An interface is a contract that the class subscribes to saying that it will honour the methods described in the interface and will implement them appropriately. For your scenario you’d create a single interface and implement it in your classes, you can then pass the instances of the various accessor classes as instances of the interface.

For example:

public interface IDataProvider
{
    void LoadData();
}

The data providers would then look as follows:

public class MyDataProvder1 : IDataProvider
{
    // Some methods

    // Must implement LoadData
    public void LoadData()
    {
        // Do something
    }
}

public class MyDataProvder2 : IDataProvider
{
    // Some methods

    // Must implement LoadData
    public void LoadData()
    {
        // Do something
    }
}

You can then pass the objects as IDataProvider as follows:

IDataProvider DataProviderA = new MyDataProvider1();
IDataProvider DataProviderB = new MyDataProvider2();

// Call function that expects an IDataProvider

DoSomething(DataProviderA);
DoSomething(DataProviderB);

…

public void DoSomething(IDataProvider DataProvider)
{
    DataProvider.LoadData();
}

Hopefully that clears it up for you.