CODEWITHSUNDEEP
c#.netentity-frameworkef-code-first
Barış Velioğlu
Barış Velioğlu

Reputation: 5817

Best Way To Filtering Child Entities In Entity Framework

I am not deleting entities. I just sign them by IsDeleted property. The problem is when I get a parent element, its all child elements are loaded even if IsDeleted propery is true or false. Then I did something like below, but I want to know is there a better way to do it ?

var result = from p in context.Set<Product>().Include(x => x.Reviews)
                        select new
                             {
                                 Product = x,
                                 ProductReviews = x.ProductReviews.Where(y => !y.IsDeleted)
                             };

 var products = new List<Product>();

            foreach (var product in result.OrderBy(x => x.Product.Id).Skip(skipRecords).Take(pageSize))
            {
                var p = new Product();
                p = product.Product;
                p.ProductReviews = product.ProductReviews.ToList();

                products.Add(p);
            }

return products;

How to improve this code block ?

Thanks

Upvotes: 0

Views: 230

Answers (1)

CptRobby
CptRobby

Reputation: 1521

What I did to address this type of situation before was to create a specific interface signifying the classes that are "flag deleted" like this and then create an Extension Method that filters them out.

If you only have one class with the IsDeleted property, then you don't need a separate interface and you can just use the class instead. But I'll assume for the moment that you do have multiple classes and that the interface is needed.

So the interface would be defined like so:

public interface IHaveIsDeleted
{
  public bool IsDeleted { get; set; }
}

Then my Extension Method would be defined in a static class like so:

public static class MyExtensionMethods
{
  public IQueryable<T> FilterDeleted(this IQueryable<T> src) where T : IHaveIsDeleted
  {
    return src.Where(x => !x.IsDeleted);
  }
}

Because this is done on an IQueryable<T>, the where clause gets built into the query that is sent to the database, so there won't be any records returned where IsDeleted is true. So all you would have to do in your example is call x.ProductReviews.FilterDeleted().

Now, the project that I was using this method in was actually using LINQ2SQL. And I'm rather new to EF myself, so there might be a more 'EF specific' way of doing this, (like perhaps some kind of Type Per Hierarchy construct, maybe?), but I just thought this would at least help make your queries simpler.

Hope that helps! ;)

Upvotes: 2

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