Question

I’m using a Generic repository pattern, as displayed in this article.

These are my POCO Classes:

public class Order
{
    public int ID { get; set; }
    public int CustomerID {get; set;}

    [InverseProperty("Order")]
    public virtual List<OrderDetail> OrderDetail {get; set;}

    public static Expression<Func<Order, bool>> OrdersFromCustomer(decimal customerId)
    {
        return f => f.CustomerID == customerId;
    }
}

public class OrderDetail
{
    public int OrderID { get; set;}
    public int ID { get; set;}
    public int ItemID { get; set;}
    public int Amount { get; set;}

    [ForeignKey("OrderID")]
    public virtual Order { get; set;}
}

so when in my program I want to get all orders by a customer I can do this:

using (MyDbContext context = new MyDbContext())
{
    MyRepository repository = new MyRepository(context);
    var orders = repository.Get(Order.OrdersFromCustomer(25));
}

It works great, but I have an issue: if I want all the orders with Amount greater than 100? How could I build a Expression for filter on the details as the OrderFromCustomer function?
I’ve tried also with LinqKit but with no results.

Answer 1

You can just chain the Where filter clauses together, for example to do so in line it would look like:

 orders = repository.Get(filter: q => q.Where(f => f.CustomerID == customerId).Where( n => n.Amount > 100);