Question

To see my problem in action, visit http://www.apoads.com and hover over the ‘Local Businesses’ menu item. It’s a series of nested unordered lists generated from a db call. Go ahead and click on a few of the items underneath ‘Local Businesses’, you’ll see that most of the categories are empty (the site is very new).

Problem: I only want to show the categories that actually contain a local business. Here’s what my category schema looks like:

int BizCatID - PK,Identity (used in FK relation to the table named Biz) int? ParentID - BizCatID of this rows parentID, null means no parent nvarchar Name - name of the category nvarchar Caption - quick description of the category 

What I’ve tried: I’ve tried to update my LINQ query like so:

from c in db.BizCategories where c.ParentID != null && c.Bizs.Count() > 0 select c; 

That obviously won’t work, cause I’ll need the parent category to show if the child category contains a business. So I tried this:

from c in db.BizCategories where c.Bizs.Count() > 0 select c; 

This doesn’t work either, as parent categories will never have any businesses under them. So it seems like I’ll need to do some sort of inverse recursion, but I’m not sure how to do that.

Or, perhaps I’m making things to hard for myself and I need to change my db schemas?

Answer 1

create classes to hold your information like so

public class BusinessCat {     public string Name{get;set;}     public string Caption{get;set;}     public List<'dunno datatype'> Children{get;set;}; }  var results = from c in BizCategories     where c.ParentID == null         select new BusinessCat{             Name = c.Name,             Caption = c.Caption,             Children =  (from d in BizCategories                     where d.ParentID == c.BizCatID && d.Bizs.Count() > 0 select d).ToList()         } 

and with this you have a list full of Children and you can simply iterate through it with a foreach.

You can also do .Join() extension method for

where d.ParentID == c.BizCatID && d.Bizs.Count()