Filter linq query

Question

Any advice on how to make this code; cleaner, more effective, just overall better!

Program has three options that can be passed int NewsId,Year and CategoryId. I collection all the data and then do additional filter base on the values that are being passed into the method.

public List<News> GetNewsbyYear(int NewsId, int Year, int CategoryId)
{
    using (var db = new NccnEcommerceEntities())
    {
        var listOfNews = (from n in db.News
                          where n.Display == true
                          select new Model.News
                            {
                                NewsId = n.NewsId,
                                Title = n.Title,
                                ReleaseDate = n.ReleaseDate,
                                Body = n.Body,
                                ExternalUrl = n.ExternalUrl,
                                LastUpdated = n.LastUpdated,
                                DisplayInBlog = n.DisplayInBlog,
                                BoilerPlate = n.BoilerPlate,
                                ItemDictionary = (from x in db.NewsCategoryXrefs
                                                  join i in db.DboItemDictionaries on x.CategoryId equals i.ItemDictionaryId
                                                  select new Model.ItemDictionary
                                                  {
                                                      Name = i.Name,
                                                      ItemDictionaryId = i.ItemDictionaryId
                                                  }).FirstOrDefault()
                            });

        if (Year > 0)
        {
            listOfNews = listOfNews.Where(item => item.ReleaseDate.Value.Year == Year);
        }
        if (CategoryId > 0)
        {
            listOfNews = listOfNews.Where(item => item.ItemDictionary.ItemDictionaryId == CategoryId);
        }
        if (NewsId > 0)
        {
            listOfNews = listOfNews.Where(item => item.NewsId == NewsId);
        }

        return listOfNews.ToList();
    }
}

Answer 1

It looks to me that you can filter the data in the original query, instead compiling the query then filtering it.

It's difficult to suggest an exact solution without access to the required objects and collections, but something like this can give you a start:

public List<News> GetNewsbyYear(int NewsId, int Year, int CategoryId)
{
    using (var db = new NccnEcommerceEntities())
    {
        return (from n in db.News
                where n.Display == true && 
                ((Year > 0 && n.ReleaseDate.Value.Year == Year) ||
                 (NewsId > 0 && n.NewsId == NewsId) ||
                 (CategorId > 0))                                                               
                select new Model.News
                {
                    NewsId = n.NewsId,
                    Title = n.Title,
                    ReleaseDate = n.ReleaseDate,
                    Body = n.Body,
                    ExternalUrl = n.ExternalUrl,
                    LastUpdated = n.LastUpdated,
                    DisplayInBlog = n.DisplayInBlog,
                    BoilerPlate = n.BoilerPlate,
                    ItemDictionary = (from x in db.NewsCategoryXrefs
                                      where CategoryID > 0 && x.CategoryId == CategoryId
                                      join i in db.DboItemDictionaries on x.CategoryId equals i.ItemDictionaryId
                                      select new Model.ItemDictionary
                                      {
                                          Name = i.Name,
                                          ItemDictionaryId = i.ItemDictionaryId
                                      }).FirstOrDefault()
                }).toList();
    }
}