I have this wcf method
Profile GetProfileInfo(string profileType, string profileName)
and a business rule:
if profileType is "A" read from database.
if profileType is "B" read from xml file.
The question is: how to implement it using a dependency injection container?
Let's first assume that you have an IProfileRepository something like this:
public interface IProfileRepository
{
Profile GetProfile(string profileName);
}
as well as two implementations: DatabaseProfileRepository
and XmlProfileRepository
. The issue is that you would like to pick the correct one based on the value of profileType.
You can do this by introducing this Abstract Factory:
public interface IProfileRepositoryFactory
{
IProfileRepository Create(string profileType);
}
Assuming that the IProfileRepositoryFactory has been injected into the service implementation, you can now implement the GetProfileInfo method like this:
public Profile GetProfileInfo(string profileType, string profileName)
{
return this.factory.Create(profileType).GetProfile(profileName);
}
A concrete implementation of IProfileRepositoryFactory might look like this:
public class ProfileRepositoryFactory : IProfileRepositoryFactory
{
private readonly IProfileRepository aRepository;
private readonly IProfileRepository bRepository;
public ProfileRepositoryFactory(IProfileRepository aRepository,
IProfileRepository bRepository)
{
if(aRepository == null)
{
throw new ArgumentNullException("aRepository");
}
if(bRepository == null)
{
throw new ArgumentNullException("bRepository");
}
this.aRepository = aRepository;
this.bRepository = bRepository;
}
public IProfileRepository Create(string profileType)
{
if(profileType == "A")
{
return this.aRepository;
}
if(profileType == "B")
{
return this.bRepository;
}
// and so on...
}
}
Now you just need to get your DI Container of choice to wire it all up for you...