How to find list of objects inside a list of objects using where ? (.Net Core Entity Framework )

Question

I am building a gaming website where Games have collection of Categories

public class Game
    {

        public int Id { get; set; }

        public string Name { get; set; }

        public virtual ICollection<CategoryMain> categoryMain { get; set; }

    }

I want to find list of Games by choosing 1 category from the list of categories.

var games= await db.Games.Include(u => u.applicationUser)
                                        .Include(c => c.categoryMain)
                                        .Where(c => c.categoryMain.Id == x) // <-- My Issue Here
                                        .ToListAsync();

Because "categoryMain" is a collection, I cannot access it's properties "Id" to filter games by category.

Previously I had Games have 1 category only, things works fine, but now I want to have the ability for games to have multiple categories, so I really need this.

Thanks

Jensen · Accepted Answer · 2020-02-21 22:26:32Z

3

You should be able to get the desired result using the .Any() method.

var games = await db.Games
                    .Include(x => x.categoryMain)
                    .Where(x => x.categoryMain.Any(y => y == categoryId)
                    .ToListAsync();

Personally, I always find it's easier to reverse the query if you're doing something like this because I find it improves readability.

Something like this:

var games = await db.CategoryMain
                    .Include(x => x.Game)
                    .Where(x => x.Id == categoryId)
                    .Select(x => x.Game)
                    .ToListAsync();

answered Feb 21, 2020 at 22:26

Jensen

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1 Comment

khalid Saud Over a year ago

It worked, thank you for your swift help, I appreciate it a lot !

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