Question

I have the following database schema :

Store
  StoreId
  Name
  ...

Order
  OrderId
  StoreId
  ....

I have a asp.net mvc backend application with a data repostory like this (simplified):

   public IQueryable<Order> GetOrders() {

        return storeDB.Orders
            .OrderByDescending(o => o.DateDue)
            .ThenByDescending(o => o.DateCreated);
    }

I have similar code to show sales, employees, products etc … I want to put a dropdown somewhere in the application to allow me to set a global filter to show only orders, employees, products, etc … from a given StoreId, if storeId is null I should show all records from all stores (remove the filter) what is the best way to do it ?

Should I set the storeId in the session and filter the data in the controller? should I add a storeId parameter in my datalayer and evalute if it’s null or not before applying the filter?

Answer 1

I would go for a List<Int> or List<Guid> or whatever DataType you use for the StoreID and use this list as a parameter in the method. Then you can eventually also show orders for multiple stores, or for a single store or for all stores. And then simply use an if statement to detect of the list contains something or nothing, something like:

public IQueryable<Order> GetOrders(List<Guid> storeIDs)
{
  if(storeIDs == null || storeIDs.Count == 0)
  {
    return storeDB.Orders
           .OrderByDescending(o => o.DateDue)
           .ThenByDescending(o => o.DateCreated);
  }
  else
  {
    return storeDB.Orders
           .Where(o => storeIDs.Contains(o.StoreID))
           .OrderByDescending(o => o.DateDue)
           .ThenByDescending(o => o.DateCreated);
  }
} 

This is a nice setup according to me. Don’t store the filter parameters in a Session or whatever. In the way described above the method can be used from / by multiple functional “places” in your application.