Updated Wiki: Adding Custom Queries to Repository

publicstaticclass CustomerRepository
{
    publicstaticdecimal GetCustomerOrderTotalByYear(
        this IRepository<Customer> customerRepository,
        int customerId, int year)
    {
        return customerRepository
            .Find(customerId)
            .Orders.SelectMany(o => o.OrderDetails)
            .Select(o => o.Quantity*o.UnitPrice).Sum();
    }
}

publicinterface ICustomerService : IService<Customer>
{
    decimal CustomerOrderTotalByYear(int customerId, int year);
}

publicclass CustomerService : Service<Customer>, ICustomerService
{
    privatereadonly IRepositoryAsync<Customer> _repository;

    public CustomerService(IRepositoryAsync<Customer> repository) : base(repository)
    {
        _repository = repository;
    }

    publicdecimal CustomerOrderTotalByYear(int customerId, int year)
    {
        return _repository.GetCustomerOrderTotalByYear(customerId, year);
    }
}

publicclass CustomerController : ODataController
{
    privatereadonly ICustomerService _customerService;

    public CustomerController(
        ICustomerService customerService)
    {
        _customerService = customerService;
    }

    publicdecimal CustomerOrderTotalByYear(int customerId, int year)
    {
        return _customerService.CustomerOrderTotalByYear(customerId, year);
    }
}